<chapt>Introduction
+<label id="intro">
<sect>What is BIRD
+<label id="what-is-bird">
-<p><label id="intro">
-The name `BIRD' is actually an acronym standing for `BIRD Internet Routing
+<p>The name `BIRD' is actually an acronym standing for `BIRD Internet Routing
Daemon'. Let's take a closer look at the meaning of the name:
<p><em/BIRD/: Well, we think we have already explained that. It's an acronym
<sect>Installing BIRD
+<label id="install">
<p>On a recent UNIX system with GNU development tools (GCC, binutils, m4, make)
and Perl, installing BIRD should be as easy as:
<sect>Running BIRD
+<label id="argv">
<p>You can pass several command-line options to bird:
<descrip>
- <tag>-c <m/config name/</tag>
+ <tag><label id="argv-config">-c <m/config name/</tag>
use given configuration file instead of <it/prefix/<file>/etc/bird.conf</file>.
- <tag>-d</tag>
+ <tag><label id="argv-debug">-d</tag>
enable debug messages and run bird in foreground.
- <tag>-D <m/filename of debug log/</tag>
+ <tag><label id="argv-log-file">-D <m/filename of debug log/</tag>
log debugging information to given file instead of stderr.
- <tag>-p</tag>
+ <tag><label id="argv-parse">-p</tag>
just parse the config file and exit. Return value is zero if the config
file is valid, nonzero if there are some errors.
- <tag>-s <m/name of communication socket/</tag>
+ <tag><label id="argv-socket">-s <m/name of communication socket/</tag>
use given filename for a socket for communications with the client,
default is <it/prefix/<file>/var/run/bird.ctl</file>.
- <tag>-P <m/name of PID file/</tag>
+ <tag><label id="argv-pid">-P <m/name of PID file/</tag>
create a PID file with given filename.
- <tag>-u <m/user/</tag>
+ <tag><label id="argv-user">-u <m/user/</tag>
drop privileges and use that user ID, see the next section for details.
- <tag>-g <m/group/</tag>
+ <tag><label id="argv-group">-g <m/group/</tag>
use that group ID, see the next section for details.
- <tag>-f</tag>
+ <tag><label id="argv-foreground">-f</tag>
run bird in foreground.
- <tag>-l</tag>
+ <tag><label id="argv-local">-l</tag>
look for a configuration file and a communication socket in the current
working directory instead of in default system locations. However, paths
specified by options <cf/-c/, <cf/-s/ have higher priority.
- <tag>-R</tag>
+ <tag><label id="argv-recovery">-R</tag>
apply graceful restart recovery after start.
</descrip>
<sect>Privileges
+<label id="privileges">
<p>BIRD, as a routing daemon, uses several privileged operations (like setting
routing table and using raw sockets). Traditionally, BIRD is executed and runs
<chapt>About routing tables
+<label id="routing-tables">
<p>BIRD has one or more routing tables which may or may not be synchronized with
OS kernel and which may or may not be synchronized with each other (see the Pipe
selected routes, some protocols (e.g. the <cf/Pipe/ protocol) receive and
process all entries in routing tables (accepted by filters).
-<p><label id="dsc-sorted">Usually, a routing table just chooses a selected route
+<p><label id="dsc-table-sorted">Usually, a routing table just chooses a selected route
from a list of entries for one network. But if the <cf/sorted/ option is
activated, these lists of entries are kept completely sorted (according to
preference or some protocol-dependent metric). This is needed for some features
<sect>Graceful restart
+<label id="graceful-restart">
<p>When BIRD is started after restart or crash, it repopulates routing tables in
an uncoordinated manner, like after clean start. This may be impractical in some
<chapt>Configuration
+<label id="config">
<sect>Introduction
+<label id="config-intro">
<p>BIRD is configured using a text configuration file. Upon startup, BIRD reads
<it/prefix/<file>/etc/bird.conf</file> (unless the <tt/-c/ command line option
<sect>Global options
+<label id="global-opts">
<p><descrip>
- <tag>include "<m/filename/"</tag>
+ <tag><label id="opt-include">include "<m/filename/"</tag>
This statement causes inclusion of a new file. <m/Filename/ could also
be a wildcard, in that case matching files are included in alphabetic
order. The maximal depth is 8. Note that this statement could be used
anywhere in the config file, not just as a top-level option.
- <tag><label id="dsc-log">log "<m/filename/"|syslog [name <m/name/]|stderr all|{ <m/list of classes/ }</tag>
+ <tag><label id="opt-log">log "<m/filename/"|syslog [name <m/name/]|stderr all|{ <m/list of classes/ }</tag>
Set logging of messages having the given class (either <cf/all/ or
<cf/{ error, trace }/ etc.) into selected destination (a file specified
as a filename string, syslog with optional name argument, or the stderr
You may specify more than one <cf/log/ line to establish logging to
multiple destinations. Default: log everything to the system log.
- <tag>debug protocols all|off|{ states, routes, filters, interfaces, events, packets }</tag>
+ <tag><label id="opt-debug-protocols">debug protocols all|off|{ states, routes, filters, interfaces, events, packets }</tag>
Set global defaults of protocol debugging options. See <cf/debug/ in the
following section. Default: off.
- <tag>debug commands <m/number/</tag>
+ <tag><label id="opt-debug-commands">debug commands <m/number/</tag>
Control logging of client connections (0 for no logging, 1 for logging
of connects and disconnects, 2 and higher for logging of all client
commands). Default: 0.
- <tag>debug latency <m/switch/</tag>
+ <tag><label id="opt-debug-latency">debug latency <m/switch/</tag>
Activate tracking of elapsed time for internal events. Recent events
could be examined using <cf/dump events/ command. Default: off.
- <tag>debug latency limit <m/time/</tag>
+ <tag><label id="opt-debug-latency-limit">debug latency limit <m/time/</tag>
If <cf/debug latency/ is enabled, this option allows to specify a limit
for elapsed time. Events exceeding the limit are logged. Default: 1 s.
- <tag>watchdog warning <m/time/</tag>
+ <tag><label id="opt-watchdog-warn">watchdog warning <m/time/</tag>
Set time limit for I/O loop cycle. If one iteration took more time to
complete, a warning is logged. Default: 5 s.
- <tag>watchdog timeout <m/time/</tag>
+ <tag><label id="opt-watchdog-timeout">watchdog timeout <m/time/</tag>
Set time limit for I/O loop cycle. If the limit is breached, BIRD is
killed by abort signal. The timeout has effective granularity of
seconds, zero means disabled. Default: disabled (0).
- <tag>mrtdump "<m/filename/"</tag>
+ <tag><label id="opt-mrtdump">mrtdump "<m/filename/"</tag>
Set MRTdump file name. This option must be specified to allow MRTdump
feature. Default: no dump file.
- <tag>mrtdump protocols all|off|{ states, messages }</tag>
+ <tag><label id="opt-mrtdump-protocols">mrtdump protocols all|off|{ states, messages }</tag>
Set global defaults of MRTdump options. See <cf/mrtdump/ in the
following section. Default: off.
- <tag>filter <m/name local variables/{ <m/commands/ }</tag>
+ <tag><label id="opt-filter">filter <m/name local variables/{ <m/commands/ }</tag>
Define a filter. You can learn more about filters in the following
chapter.
- <tag>function <m/name/ (<m/parameters/) <m/local variables/ { <m/commands/ }</tag>
+ <tag><label id="opt-function">function <m/name/ (<m/parameters/) <m/local variables/ { <m/commands/ }</tag>
Define a function. You can learn more about functions in the following chapter.
- <tag>protocol rip|ospf|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag>
+ <tag><label id="opt-protocol">protocol rip|ospf|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag>
Define a protocol instance called <cf><m/name/</cf> (or with a name like
"rip5" generated automatically if you don't specify any
<cf><m/name/</cf>). You can learn more about configuring protocols in
<cf><m/name2/</cf> You can run more than one instance of most protocols
(like RIP or BGP). By default, no instances are configured.
- <tag>template rip|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag>
+ <tag><label id="opt-template">template rip|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag>
Define a protocol template instance called <m/name/ (or with a name like
"bgp1" generated automatically if you don't specify any <m/name/).
Protocol templates can be used to group common options when many
expression and the name of the template. At the moment templates (and
<cf/from/ expression) are not implemented for OSPF protocol.
- <tag>define <m/constant/ = <m/expression/</tag>
+ <tag><label id="opt-define">define <m/constant/ = <m/expression/</tag>
Define a constant. You can use it later in every place you could use a
value of the same type. Besides, there are some predefined numeric
constants based on /etc/iproute2/rt_* files. A list of defined constants
can be seen (together with other symbols) using 'show symbols' command.
- <tag>router id <m/IPv4 address/</tag>
- Set BIRD's router ID. It's a world-wide unique identification of your
+ <tag><label id="opt-router-id">router id <m/IPv4 address/</tag>
+ Set BIRD's router ID. It's a world-wide unique identification of your
router, usually one of router's IPv4 addresses. Default: in IPv4
version, the lowest IP address of a non-loopback interface. In IPv6
version, this option is mandatory.
- <tag>router id from [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...]</tag>
+ <tag><label id="opt-router-id-from">router id from [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...]</tag>
Set BIRD's router ID based on an IP address of an interface specified by
an interface pattern. The option is applicable for IPv4 version only.
- See <ref id="dsc-iface" name="interface"> section for detailed
+ See <ref id="proto-iface" name="interface"> section for detailed
description of interface patterns with extended clauses.
- <tag>listen bgp [address <m/address/] [port <m/port/] [dual]</tag>
+ <tag><label id="opt-listen-bgp">listen bgp [address <m/address/] [port <m/port/] [dual]</tag>
This option allows to specify address and port where BGP protocol should
listen. It is global option as listening socket is common to all BGP
instances. Default is to listen on all addresses (0.0.0.0) and port 179.
BIRD would accept IPv6 routes only). Such behavior was default in older
versions of BIRD.
- <tag>graceful restart wait <m/number/</tag>
+ <tag><label id="opt-graceful-restart">graceful restart wait <m/number/</tag>
During graceful restart recovery, BIRD waits for convergence of routing
protocols. This option allows to specify a timeout for the recovery to
prevent waiting indefinitely if some protocols cannot converge. Default:
240 seconds.
- <tag>timeformat route|protocol|base|log "<m/format1/" [<m/limit/ "<m/format2/"]</tag>
+ <tag><label id="opt-timeformat">timeformat route|protocol|base|log "<m/format1/" [<m/limit/ "<m/format2/"]</tag>
This option allows to specify a format of date/time used by BIRD. The
first argument specifies for which purpose such format is used.
<cf/route/ is a format used in 'show route' command output,
hh:mm:ss) for <cf/base/ and <cf/log/. These timeformats could be set by
<cf/old short/ and <cf/old long/ compatibility shorthands.
- <tag>table <m/name/ [sorted]</tag>
+ <tag><label id="opt-table">table <m/name/ [sorted]</tag>
Create a new routing table. The default routing table is created
implicitly, other routing tables have to be added by this command.
Option <cf/sorted/ can be used to enable sorting of routes, see
- <ref id="dsc-sorted" name="sorted table"> description for details.
+ <ref id="dsc-table-sorted" name="sorted table"> description for details.
- <tag>roa table <m/name/ [ { roa table options ... } ]</tag>
+ <tag><label id="opt-roa-table">roa table <m/name/ [ { roa table options ... } ]</tag>
Create a new ROA (Route Origin Authorization) table. ROA tables can be
used to validate route origination of BGP routes. A ROA table contains
ROA entries, each consist of a network prefix, a max prefix length and
ROA entries. The option may be used multiple times. Other entries can be
added dynamically by <cf/add roa/ command.
- <tag>eval <m/expr/</tag>
+ <tag><label id="opt-eval">eval <m/expr/</tag>
Evaluates given filter expression. It is used by us for testing of filters.
</descrip>
<sect>Protocol options
+<label id="protocol-opts">
<p>For each protocol instance, you can configure a bunch of options. Some of
them (those described in this section) are generic, some are specific to the
agreement").
<descrip>
- <tag>preference <m/expr/</tag>
+ <tag><label id="proto-preference">preference <m/expr/</tag>
Sets the preference of routes generated by this protocol. Default:
protocol dependent.
- <tag>disabled <m/switch/</tag>
+ <tag><label id="proto-disabled">disabled <m/switch/</tag>
Disables the protocol. You can change the disable/enable status from the
command line interface without needing to touch the configuration.
Disabled protocols are not activated. Default: protocol is enabled.
- <tag>debug all|off|{ states, routes, filters, interfaces, events, packets }</tag>
+ <tag><label id="proto-debug">debug all|off|{ states, routes, filters, interfaces, events, packets }</tag>
Set protocol debugging options. If asked, each protocol is capable of
writing trace messages about its work to the log (with category
<cf/trace/). You can either request printing of <cf/all/ trace messages
protocol, <cf/events/ for events internal to the protocol and <cf/packets/
for packets sent and received by the protocol. Default: off.
- <tag>mrtdump all|off|{ states, messages }</tag>
+ <tag><label id="proto-mrtdump">mrtdump all|off|{ states, messages }</tag>
Set protocol MRTdump flags. MRTdump is a standard binary format for
logging information from routing protocols and daemons. These flags
control what kind of information is logged from the protocol to the
BGP protocol, <cf/states/ logs BGP state changes and <cf/messages/ logs
received BGP messages. Other protocols does not support MRTdump yet.
- <tag>router id <m/IPv4 address/</tag>
+ <tag><label id="proto-router-id">router id <m/IPv4 address/</tag>
This option can be used to override global router id for a given
protocol. Default: uses global router id.
- <tag>import all | none | filter <m/name/ | filter { <m/filter commands/ } | where <m/filter expression/</tag>
+ <tag><label id="proto-import">import all | none | filter <m/name/ | filter { <m/filter commands/ } | where <m/filter expression/</tag>
Specify a filter to be used for filtering routes coming from the
protocol to the routing table. <cf/all/ is shorthand for <cf/where true/
and <cf/none/ is shorthand for <cf/where false/. Default: <cf/all/.
- <tag>export <m/filter/</tag>
+ <tag><label id="proto-export">export <m/filter/</tag>
This is similar to the <cf>import</cf> keyword, except that it works in
the direction from the routing table to the protocol. Default: <cf/none/.
- <tag>import keep filtered <m/switch/</tag>
+ <tag><label id="proto-import-keep-filtered">import keep filtered <m/switch/</tag>
Usually, if an import filter rejects a route, the route is forgotten.
When this option is active, these routes are kept in the routing table,
but they are hidden and not propagated to other protocols. But it is
possible to show them using <cf/show route filtered/. Note that this
option does not work for the pipe protocol. Default: off.
- <tag><label id="import-limit">import limit [<m/number/ | off ] [action warn | block | restart | disable]</tag>
+ <tag><label id="proto-import-limit">import limit [<m/number/ | off ] [action warn | block | restart | disable]</tag>
Specify an import route limit (a maximum number of routes imported from
the protocol) and optionally the action to be taken when the limit is
hit. Warn action just prints warning log message. Block action discards
action if an action is not explicitly specified. Note that limits are
reset during protocol reconfigure, reload or restart. Default: <cf/off/.
- <tag>receive limit [<m/number/ | off ] [action warn | block | restart | disable]</tag>
+ <tag><label id="proto-receive-limit">receive limit [<m/number/ | off ] [action warn | block | restart | disable]</tag>
Specify an receive route limit (a maximum number of routes received from
the protocol and remembered). It works almost identically to <cf>import
limit</cf> option, the only difference is that if <cf/import keep
on the contrary, counts accepted routes only and routes blocked by the
limit are handled like filtered routes. Default: <cf/off/.
- <tag>export limit [ <m/number/ | off ] [action warn | block | restart | disable]</tag>
+ <tag><label id="proto-export-limit">export limit [ <m/number/ | off ] [action warn | block | restart | disable]</tag>
Specify an export route limit, works similarly to the <cf>import
limit</cf> option, but for the routes exported to the protocol. This
option is experimental, there are some problems in details of its
updates of already accepted routes -- and these details will probably
change in the future. Default: <cf/off/.
- <tag>description "<m/text/"</tag>
+ <tag><label id="proto-description">description "<m/text/"</tag>
This is an optional description of the protocol. It is displayed as a
part of the output of 'show route all' command.
- <tag>table <m/name/</tag>
+ <tag><label id="proto-table">table <m/name/</tag>
Connect this protocol to a non-default routing table.
</descrip>
<p>There are several options that give sense only with certain protocols:
<descrip>
- <tag><label id="dsc-iface">interface [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...] [ { <m/option/ ; [...] } ]</tag>
+ <tag><label id="proto-iface">interface [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...] [ { <m/option/ ; [...] } ]</tag>
Specifies a set of interfaces on which the protocol is activated with
given interface-specific options. A set of interfaces specified by one
interface option is described using an interface pattern. The interface
<cf>interface "eth*" 192.168.1.0/24;</cf> - start the protocol on all
ethernet interfaces that have address from 192.168.1.0/24.
- <tag><label id="dsc-prio">tx class|dscp <m/num/</tag>
+ <tag><label id="proto-tx-class">tx class|dscp <m/num/</tag>
This option specifies the value of ToS/DS/Class field in IP headers of
the outgoing protocol packets. This may affect how the protocol packets
are processed by the network relative to the other network traffic. With
keyword, the value (0-63) is used just for the DS field in the octet.
Default value is 0xc0 (DSCP 0x30 - CS6).
- <tag>tx priority <m/num/</tag>
+ <tag><label id="proto-tx-priority">tx priority <m/num/</tag>
This option specifies the local packet priority. This may affect how the
protocol packets are processed in the local TX queues. This option is
Linux specific. Default value is 7 (highest priority, privileged traffic).
- <tag><label id="dsc-pass">password "<m/password/" [ { id <m/num/; generate from <m/time/; generate to <m/time/; accept from <m/time/; accept to <m/time/; } ]</tag>
+ <tag><label id="proto-pass">password "<m/password/" [ { id <m/num/; generate from <m/time/; generate to <m/time/; accept from <m/time/; accept to <m/time/; } ]</tag>
Specifies a password that can be used by the protocol. Password option
can be used more times to specify more passwords. If more passwords are
specified, it is a protocol-dependent decision which one is really
This option is allowed in OSPF and RIP protocols. BGP has also
<cf/password/ option, but it is slightly different and described
separately.
-
Default: none.
</descrip>
<p>Password option can contain section with some (not necessary all) password sub-options:
<descrip>
- <tag>id <M>num</M></tag>
+ <tag><label id="proto-pass-id">id <M>num</M></tag>
ID of the password, (1-255). If it is not used, BIRD will choose ID based
on an order of the password item in the interface. For example, second
password item in one interface will have default ID 2. ID is used by
some routing protocols to identify which password was used to
authenticate protocol packets.
- <tag>generate from "<m/time/"</tag>
+ <tag><label id="proto-pass-gen-from">generate from "<m/time/"</tag>
The start time of the usage of the password for packet signing.
The format of <cf><m/time/</cf> is <tt>dd-mm-yyyy HH:MM:SS</tt>.
- <tag>generate to "<m/time/"</tag>
+ <tag><label id="proto-pass-gen-to">generate to "<m/time/"</tag>
The last time of the usage of the password for packet signing.
- <tag>accept from "<m/time/"</tag>
+ <tag><label id="proto-pass-accept-from">accept from "<m/time/"</tag>
The start time of the usage of the password for packet verification.
- <tag>accept to "<m/time/"</tag>
+ <tag><label id="proto-pass-accept-to">accept to "<m/time/"</tag>
The last time of the usage of the password for packet verification.
</descrip>
<chapt>Remote control
+<label id="remote-control">
<p>You can use the command-line client <file>birdc</file> to talk with a running
BIRD. Communication is done using a <file/bird.ctl/ UNIX domain socket (unless
<p>Here is a brief list of supported functions:
<descrip>
- <tag>show status</tag>
+ <tag><label id="cli-show-status">show status</tag>
Show router status, that is BIRD version, uptime and time from last
reconfiguration.
- <tag>show interfaces [summary]</tag>
+ <tag><label id="cli-show-interfaces">show interfaces [summary]</tag>
Show the list of interfaces. For each interface, print its type, state,
MTU and addresses assigned.
- <tag>show protocols [all]</tag>
+ <tag><label id="cli-show-protocols">show protocols [all]</tag>
Show list of protocol instances along with tables they are connected to
and protocol status, possibly giving verbose information, if <cf/all/ is
specified.
- <tag>show ospf interface [<m/name/] ["<m/interface/"]</tag>
+ <tag><label id="cli-show-ospf-iface">show ospf interface [<m/name/] ["<m/interface/"]</tag>
Show detailed information about OSPF interfaces.
- <tag>show ospf neighbors [<m/name/] ["<m/interface/"]</tag>
+ <tag><label id="cli-show-ospf-neighbors">show ospf neighbors [<m/name/] ["<m/interface/"]</tag>
Show a list of OSPF neighbors and a state of adjacency to them.
- <tag>show ospf state [all] [<m/name/]</tag>
+ <tag><label id="cli-show-ospf-state">show ospf state [all] [<m/name/]</tag>
Show detailed information about OSPF areas based on a content of the
link-state database. It shows network topology, stub networks,
aggregated networks and routers from other areas and external routes.
<cf/all/ to show information about all network nodes in the link-state
database.
- <tag>show ospf topology [all] [<m/name/]</tag>
+ <tag><label id="cli-show-ospf-topology">show ospf topology [all] [<m/name/]</tag>
Show a topology of OSPF areas based on a content of the link-state
database. It is just a stripped-down version of 'show ospf state'.
- <tag>show ospf lsadb [global | area <m/id/ | link] [type <m/num/] [lsid <m/id/] [self | router <m/id/] [<m/name/] </tag>
+ <tag><label id="cli-show-ospf-lsadb">show ospf lsadb [global | area <m/id/ | link] [type <m/num/] [lsid <m/id/] [self | router <m/id/] [<m/name/] </tag>
Show contents of an OSPF LSA database. Options could be used to filter
entries.
- <tag>show rip interfaces [<m/name/] ["<m/interface/"]</tag>
+ <tag><label id="cli-show-rip-interfaces">show rip interfaces [<m/name/] ["<m/interface/"]</tag>
Show detailed information about RIP interfaces.
- <tag>show rip neighbors [<m/name/] ["<m/interface/"]</tag>
+ <tag><label id="cli-show-rip-neighbors">show rip neighbors [<m/name/] ["<m/interface/"]</tag>
Show a list of RIP neighbors and associated state.
- <tag>show static [<m/name/]</tag>
+ <tag><label id="cli-show-static">show static [<m/name/]</tag>
Show detailed information about static routes.
- <tag>show bfd sessions [<m/name/]</tag>
+ <tag><label id="cli-show-bfd-sessions">show bfd sessions [<m/name/]</tag>
Show information about BFD sessions.
- <tag>show symbols [table|filter|function|protocol|template|roa|<m/symbol/]</tag>
+ <tag><label id="cli-show-symbols">show symbols [table|filter|function|protocol|template|roa|<m/symbol/]</tag>
Show the list of symbols defined in the configuration (names of
protocols, routing tables etc.).
- <tag>show route [[for] <m/prefix/|<m/IP/] [table <m/sym/] [filter <m/f/|where <m/c/] [(export|preexport|noexport) <m/p/] [protocol <m/p/] [<m/options/]</tag>
+ <tag><label id="cli-show-route">show route [[for] <m/prefix/|<m/IP/] [table <m/sym/] [filter <m/f/|where <m/c/] [(export|preexport|noexport) <m/p/] [protocol <m/p/] [<m/options/]</tag>
Show contents of a routing table (by default of the main one or the
table attached to a respective protocol), that is routes, their metrics
and (in case the <cf/all/ switch is given) all their attributes.
number of networks, number of routes before and after filtering). If
you use <cf/count/ instead, only the statistics will be printed.
- <tag>show roa [<m/prefix/ | in <m/prefix/ | for <m/prefix/] [as <m/num/] [table <m/t/>]</tag>
+ <tag><label id="cli-show-roa">show roa [<m/prefix/ | in <m/prefix/ | for <m/prefix/] [as <m/num/] [table <m/t/>]</tag>
Show contents of a ROA table (by default of the first one). You can
specify a <m/prefix/ to print ROA entries for a specific network. If you
use <cf>for <m/prefix/</cf>, you'll get all entries relevant for route
entries covered by the network prefix. You could also use <cf/as/ option
to show just entries for given AS.
- <tag>add roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag>
+ <tag><label id="cli-add-roa">add roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag>
Add a new ROA entry to a ROA table. Such entry is called <it/dynamic/
compared to <it/static/ entries specified in the config file. These
dynamic entries survive reconfiguration.
- <tag>delete roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag>
+ <tag><label id="cli-delete-roa">delete roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag>
Delete the specified ROA entry from a ROA table. Only dynamic ROA
entries (i.e., the ones added by <cf/add roa/ command) can be deleted.
- <tag>flush roa [table <m/t/>]</tag>
+ <tag><label id="cli-flush-roa">flush roa [table <m/t/>]</tag>
Remove all dynamic ROA entries from a ROA table.
- <tag>configure [soft] ["<m/config file/"] [timeout [<m/num/]]</tag>
+ <tag><label id="cli-configure">configure [soft] ["<m/config file/"] [timeout [<m/num/]]</tag>
Reload configuration from a given file. BIRD will smoothly switch itself
to the new configuration, protocols are reconfigured if possible,
restarted otherwise. Changes in filters usually lead to restart of
config timeout expiration is equivalent to <cf/configure undo/
command. The timeout duration could be specified, default is 300 s.
- <tag>configure confirm</tag>
+ <tag><label id="cli-configure-confirm">configure confirm</tag>
Deactivate the config undo timer and therefore confirm the current
configuration.
- <tag>configure undo</tag>
+ <tag><label id="cli-configure-undo">configure undo</tag>
Undo the last configuration change and smoothly switch back to the
previous (stored) configuration. If the last configuration change was
soft, the undo change is also soft. There is only one level of undo, but
immediately in a row and the intermediate ones are skipped then the undo
also skips them back.
- <tag>configure check ["<m/config file/"]</tag>
+ <tag><label id="cli-configure-check">configure check ["<m/config file/"]</tag>
Read and parse given config file, but do not use it. useful for checking
syntactic and some semantic validity of an config file.
- <tag>enable|disable|restart <m/name/|"<m/pattern/"|all</tag>
+ <tag><label id="cli-enable-disable-restart">enable|disable|restart <m/name/|"<m/pattern/"|all</tag>
Enable, disable or restart a given protocol instance, instances matching
the <cf><m/pattern/</cf> or <cf/all/ instances.
- <tag>reload [in|out] <m/name/|"<m/pattern/"|all</tag>
+ <tag><label id="cli-reload">reload [in|out] <m/name/|"<m/pattern/"|all</tag>
Reload a given protocol instance, that means re-import routes from the
protocol instance and re-export preferred routes to the instance. If
<cf/in/ or <cf/out/ options are used, the command is restricted to one
pipe protocol, both directions are always reloaded together (<cf/in/ or
<cf/out/ options are ignored in that case).
- <tag/down/
+ <tag><label id="cli-down">down</tag>
Shut BIRD down.
- <tag>debug <m/protocol/|<m/pattern/|all all|off|{ states | routes | filters | events | packets }</tag>
+ <tag><label id="cli-debug">debug <m/protocol/|<m/pattern/|all all|off|{ states | routes | filters | events | packets }</tag>
Control protocol debugging.
- <tag>dump resources|sockets|interfaces|neighbors|attributes|routes|protocols</tag>
+ <tag><label id="cli-dump">dump resources|sockets|interfaces|neighbors|attributes|routes|protocols</tag>
Dump contents of internal data structures to the debugging output.
- <tag>echo all|off|{ <m/list of log classes/ } [ <m/buffer-size/ ]</tag>
+ <tag><label id="cli-echo">echo all|off|{ <m/list of log classes/ } [ <m/buffer-size/ ]</tag>
Control echoing of log messages to the command-line output.
- See <ref id="dsc-log" name="log option"> for a list of log classes.
+ See <ref id="opt-log" name="log option"> for a list of log classes.
- <tag>eval <m/expr/</tag>
+ <tag><label id="cli-eval">eval <m/expr/</tag>
Evaluate given expression.
</descrip>
<chapt>Filters
+<label id="filters">
<sect>Introduction
+<label id="filters-intro">
<p>BIRD contains a simple programming language. (No, it can't yet read mail :-).
There are two objects in this language: filters and functions. Filters are
<sect>Data types
+<label id="data-types">
<p>Each variable and each value has certain type. Booleans, integers and enums
are incompatible with each other (that is to prevent you from shooting in the
foot).
<descrip>
- <tag/bool/
+ <tag><label id="type-bool">bool</tag>
This is a boolean type, it can have only two values, <cf/true/ and
<cf/false/. Boolean is the only type you can use in <cf/if/ statements.
- <tag/int/
+ <tag><label id="type-int">int</tag>
This is a general integer type. It is an unsigned 32bit type; i.e., you
can expect it to store values from 0 to 4294967295. Overflows are not
checked. You can use <cf/0x1234/ syntax to write hexadecimal values.
- <tag/pair/
+ <tag><label id="type-pair">pair</tag>
This is a pair of two short integers. Each component can have values
from 0 to 65535. Literals of this type are written as <cf/(1234,5678)/.
The same syntax can also be used to construct a pair from two arbitrary
integer expressions (for example <cf/(1+2,a)/).
- <tag/quad/
+ <tag><label id="type-quad">quad</tag>
This is a dotted quad of numbers used to represent router IDs (and
others). Each component can have a value from 0 to 255. Literals of
this type are written like IPv4 addresses.
- <tag/string/
+ <tag><label id="type-string">string</tag>
This is a string of characters. There are no ways to modify strings in
filters. You can pass them between functions, assign them to variables
of type <cf/string/, print such variables, use standard string
!˜/) operators could be used to match a string value against
a shell pattern (represented also as a string).
- <tag/ip/
+ <tag><label id="type-ip">ip</tag>
This type can hold a single IP address. Depending on the compile-time
configuration of BIRD you are using, it is either an IPv4 or IPv6
address. IP addresses are written in the standard notation
first <cf><M>num</M></cf> bits from the IP address. So
<cf/1.2.3.4.mask(8) = 1.0.0.0/ is true.
- <tag/prefix/
+ <tag><label id="type-prefix">prefix</tag>
This type can hold a network prefix consisting of IP address and prefix
length. Prefix literals are written as <cf><m/ipaddress//<m/pxlen/</cf>,
or <cf><m>ipaddress</m>/<m>netmask</m></cf>. There are two special
pair, and <cf/.len/, which separates prefix length from the pair.
So <cf>1.2.0.0/16.len = 16</cf> is true.
- <tag/ec/
+ <tag><label id="type-ec">ec</tag>
This is a specialized type used to represent BGP extended community
values. It is essentially a 64bit value, literals of this type are
usually written as <cf>(<m/kind/, <m/key/, <m/value/)</cf>, where
for <cf/key/ and <cf/value/ parts, (e.g. <cf/(ro, myas, 3*10)/, where
<cf/myas/ is an integer variable).
- <tag/lc/
+ <tag><label id="type-lc">lc</tag>
This is a specialized type used to represent BGP large community
values. It is essentially a triplet of 32bit values, where the first
value is reserved for the AS number of the issuer, while meaning of
pairs, LCs can be constructed using expressions for its parts, (e.g.
<cf/(myas, 10+20, 3*10)/, where <cf/myas/ is an integer variable).
- <tag/int|pair|quad|ip|prefix|ec|lc|enum set/
+ <tag><label id="type-set">int|pair|quad|ip|prefix|ec|lc|enum set</tag>
Filters recognize four types of sets. Sets are similar to strings: you
can pass them around but you can't modify them. Literals of type <cf>int
set</cf> look like <cf> [ 1, 2, 5..7 ]</cf>. As you can see, both simple
<cf>192.168.0.0/16{16,24}</cf> and <cf>192.168.0.0/16 ge 24</cf> as
<cf>192.168.0.0/16{24,32}</cf>.
- <tag/enum/
+ <tag><label id="type-enum">enum</tag>
Enumeration types are fixed sets of possibilities. You can't define your
own variables of such type, but some route attributes are of enumeration
type. Enumeration types are incompatible with each other.
- <tag/bgppath/
+ <tag><label id="type-bgppath">bgppath</tag>
BGP path is a list of autonomous system numbers. You can't write
literals of this type. There are several special operators on bgppaths:
<cf><m/P/.prepend(<m/A/);</cf> if <m/P/ is appropriate route attribute
(for example <cf/bgp_path/). Similarly for <cf/delete/ and <cf/filter/.
- <tag/bgpmask/
+ <tag><label id="type-bgpmask">bgpmask</tag>
BGP masks are patterns used for BGP path matching (using <cf>path
˜ [= 2 3 5 * =]</cf> syntax). The masks resemble wildcard patterns
as used by UNIX shells. Autonomous system numbers match themselves,
There is also old (deprecated) syntax that uses / .. / instead of [= .. =]
and ? instead of *.
- <tag/clist/
+ <tag><label id="type-clist">clist</tag>
Clist is similar to a set, except that unlike other sets, it can be
modified. The type is used for community list (a set of pairs) and for
cluster list (a set of quads). There exist no literals of this type.
<cf><m/C/.add(<m/P/);</cf> if <m/C/ is appropriate route attribute (for
example <cf/bgp_community/). Similarly for <cf/delete/ and <cf/filter/.
- <tag/eclist/
+ <tag><label id="type-eclist">eclist</tag>
Eclist is a data type used for BGP extended community lists. Eclists
are very similar to clists, but they are sets of ECs instead of pairs.
The same operations (like <cf/add/, <cf/delete/ or <cf/˜/ and
<sect>Operators
+<label id="operators">
<p>The filter language supports common integer operators <cf>(+,-,*,/)</cf>,
parentheses <cf/(a*(b+c))/, comparison <cf/(a=b, a!=b, a<b, a>=b)/.
<sect>Control structures
+<label id="control-structures">
<p>Filters support two control structures: conditions and case switches.
<sect>Route attributes
+<label id="route-attributes">
<p>A filter is implicitly passed a route, and it can access its attributes just
like it accesses variables. Attempts to access undefined attribute result in a
clist for most purposes.
<descrip>
- <tag><m/prefix/ net</tag>
+ <tag><label id="rta-net"><m/prefix/ net</tag>
Network the route is talking about. Read-only. (See the chapter about
routing tables.)
- <tag><m/enum/ scope</tag>
+ <tag><label id="rta-scope"><m/enum/ scope</tag>
The scope of the route. Possible values: <cf/SCOPE_HOST/ for routes
local to this host, <cf/SCOPE_LINK/ for those specific for a physical
link, <cf/SCOPE_SITE/ and <cf/SCOPE_ORGANIZATION/ for private routes and
interpreted by BIRD and can be used to mark routes in filters. The
default value for new routes is <cf/SCOPE_UNIVERSE/.
- <tag><m/int/ preference</tag>
+ <tag><label id="rta-preference"><m/int/ preference</tag>
Preference of the route. Valid values are 0-65535. (See the chapter
about routing tables.)
- <tag><m/ip/ from</tag>
+ <tag><label id="rta-from"><m/ip/ from</tag>
The router which the route has originated from.
- <tag><m/ip/ gw</tag>
+ <tag><label id="rta-gw"><m/ip/ gw</tag>
Next hop packets routed using this route should be forwarded to.
- <tag><m/string/ proto</tag>
+ <tag><label id="rta-proto"><m/string/ proto</tag>
The name of the protocol which the route has been imported from.
Read-only.
- <tag><m/enum/ source</tag>
+ <tag><label id="rta-source"><m/enum/ source</tag>
what protocol has told me about this route. Possible values:
<cf/RTS_DUMMY/, <cf/RTS_STATIC/, <cf/RTS_INHERIT/, <cf/RTS_DEVICE/,
<cf/RTS_STATIC_DEVICE/, <cf/RTS_REDIRECT/, <cf/RTS_RIP/, <cf/RTS_OSPF/,
<cf/RTS_OSPF_IA/, <cf/RTS_OSPF_EXT1/, <cf/RTS_OSPF_EXT2/, <cf/RTS_BGP/,
<cf/RTS_PIPE/, <cf/RTS_BABEL/.
- <tag><m/enum/ cast</tag>
+ <tag><label id="rta-cast"><m/enum/ cast</tag>
Route type (Currently <cf/RTC_UNICAST/ for normal routes,
<cf/RTC_BROADCAST/, <cf/RTC_MULTICAST/, <cf/RTC_ANYCAST/ will be used in
the future for broadcast, multicast and anycast routes). Read-only.
- <tag><m/enum/ dest</tag>
+ <tag><label id="rta-dest"><m/enum/ dest</tag>
Type of destination the packets should be sent to
(<cf/RTD_ROUTER/ for forwarding to a neighboring router,
<cf/RTD_DEVICE/ for routing to a directly-connected network,
messages). Can be changed, but only to <cf/RTD_BLACKHOLE/,
<cf/RTD_UNREACHABLE/ or <cf/RTD_PROHIBIT/.
- <tag><m/string/ ifname</tag>
+ <tag><label id="rta-ifname"><m/string/ ifname</tag>
Name of the outgoing interface. Sink routes (like blackhole, unreachable
or prohibit) and multipath routes have no interface associated with
them, so <cf/ifname/ returns an empty string for such routes. Read-only.
- <tag><m/int/ ifindex</tag>
+ <tag><label id="rta-ifindex"><m/int/ ifindex</tag>
Index of the outgoing interface. System wide index of the interface. May
be used for interface matching, however indexes might change on interface
creation/removal. Zero is returned for routes with undefined outgoing
interfaces. Read-only.
- <tag><m/int/ igp_metric</tag>
+ <tag><label id="rta-igp-metric"><m/int/ igp_metric</tag>
The optional attribute that can be used to specify a distance to the
network for routes that do not have a native protocol metric attribute
(like <cf/ospf_metric1/ for OSPF routes). It is used mainly by BGP to
<sect>Other statements
+<label id="other-statements">
<p>The following statements are available:
<descrip>
- <tag><m/variable/ = <m/expr/</tag>
+ <tag><label id="assignment"><m/variable/ = <m/expr/</tag>
Set variable to a given value.
- <tag>accept|reject [ <m/expr/ ]</tag>
+ <tag><label id="filter-accept-reject">accept|reject [ <m/expr/ ]</tag>
Accept or reject the route, possibly printing <cf><m>expr</m></cf>.
- <tag>return <m/expr/</tag>
+ <tag><label id="return">return <m/expr/</tag>
Return <cf><m>expr</m></cf> from the current function, the function ends
at this point.
- <tag>print|printn <m/expr/ [<m/, expr.../]</tag>
+ <tag><label id="print">print|printn <m/expr/ [<m/, expr.../]</tag>
Prints given expressions; useful mainly while debugging filters. The
<cf/printn/ variant does not terminate the line.
- <tag>quitbird</tag>
+ <tag><label id="quitbird">quitbird</tag>
Terminates BIRD. Useful when debugging the filter interpreter.
</descrip>
<chapt>Protocols
+<label id="protocols">
<sect>Babel
+<label id="babel">
<sect1>Introduction
+<label id="babel-intro">
<p>The Babel protocol (RFC6126) is a loop-avoiding distance-vector routing
protocol that is robust and efficient both in ordinary wired networks and in
<p>The Babel protocol implementation in BIRD is currently in alpha stage.
<sect1>Configuration
+<label id="babel-config">
<p>Babel supports no global configuration options apart from those common to all
other protocols, but supports the following per-interface configuration options:
</code>
<descrip>
- <tag>type wired|wireless </tag>
+ <tag><label id="babel-type">type wired|wireless </tag>
This option specifies the interface type: Wired or wireless. Wired
interfaces are considered more reliable, and so the default hello
interval is higher, and a neighbour is considered unreachable after only
when packets are lost rather than the more binary up/down mechanism of
wired type links. Default: <cf/wired/.
- <tag>rxcost <m/num/</tag>
+ <tag><label id="babel-rxcost">rxcost <m/num/</tag>
This specifies the RX cost of the interface. The route metrics will be
computed from this value with a mechanism determined by the interface
<cf/type/. Default: 96 for wired interfaces, 256 for wireless.
- <tag>hello interval <m/num/</tag>
+ <tag><label id="babel-hello">hello interval <m/num/</tag>
Interval at which periodic "hello" messages are sent on this interface,
in seconds. Default: 4 seconds.
- <tag>update interval <m/num/</tag>
+ <tag><label id="babel-update">update interval <m/num/</tag>
Interval at which periodic (full) updates are sent. Default: 4 times the
hello interval.
- <tag>port <m/number/</tag>
+ <tag><label id="babel-port">port <m/number/</tag>
This option selects an UDP port to operate on. The default is to operate
on port 6696 as specified in the Babel RFC.
- <tag>tx class|dscp|priority <m/number/</tag>
+ <tag><label id="babel-tx-class">tx class|dscp|priority <m/number/</tag>
These options specify the ToS/DiffServ/Traffic class/Priority of the
- outgoing Babel packets. See <ref id="dsc-prio" name="tx class"> common
+ outgoing Babel packets. See <ref id="proto-tx-class" name="tx class"> common
option for detailed description.
- <tag>rx buffer <m/number/</tag>
+ <tag><label id="babel-rx-buffer">rx buffer <m/number/</tag>
This option specifies the size of buffers used for packet processing.
The buffer size should be bigger than maximal size of received packets.
The default value is the interface MTU, and the value will be clamped to a
minimum of 512 bytes + IP packet overhead.
- <tag>tx length <m/number/</tag>
+ <tag><label id="babel-tx-length">tx length <m/number/</tag>
This option specifies the maximum length of generated Babel packets. To
avoid IP fragmentation, it should not exceed the interface MTU value.
The default value is the interface MTU value, and the value will be
clamped to a minimum of 512 bytes + IP packet overhead.
- <tag>check link <m/switch/</tag>
+ <tag><label id="babel-check-link">check link <m/switch/</tag>
If set, the hardware link state (as reported by OS) is taken into
consideration. When the link disappears (e.g. an ethernet cable is
unplugged), neighbors are immediately considered unreachable and all
</descrip>
<sect1>Attributes
+<label id="babel-attr">
<p>Babel defines just one attribute: the internal babel metric of the route. It
is exposed as the <cf/babel_metric/ attribute and has range from 1 to infinity
(65535).
<sect1>Example
+<label id="babel-exam">
<p><code>
protocol babel {
<sect>BFD
-<label id="sect-bfd">
+<label id="bfd">
<sect1>Introduction
+<label id="bfd-intro">
<p>Bidirectional Forwarding Detection (BFD) is not a routing protocol itself, it
is an independent tool providing liveness and failure detection. Routing
<cf>/proc/sys/net/ipv4/ip_local_port_range</cf>
<sect1>Configuration
+<label id="bfd-config">
<p>BFD configuration consists mainly of multiple definitions of interfaces.
Most BFD config options are session specific. When a new session is requested
</code>
<descrip>
- <tag>interface <m/pattern [, ...]/ { <m/options/ }</tag>
+ <tag><label id="bfd-iface">interface <m/pattern [, ...]/ { <m/options/ }</tag>
Interface definitions allow to specify options for sessions associated
with such interfaces and also may contain interface specific options.
- See <ref id="dsc-iface" name="interface"> common option for a detailed
+ See <ref id="proto-iface" name="interface"> common option for a detailed
description of interface patterns. Note that contrary to the behavior of
<cf/interface/ definitions of other protocols, BFD protocol would accept
sessions (in default configuration) even on interfaces not covered by
such definitions.
- <tag>multihop { <m/options/ }</tag>
+ <tag><label id="bfd-multihop">multihop { <m/options/ }</tag>
Multihop definitions allow to specify options for multihop BFD sessions,
in the same manner as <cf/interface/ definitions are used for directly
connected sessions. Currently only one such definition (for all multihop
sessions) could be used.
- <tag>neighbor <m/ip/ [dev "<m/interface/"] [local <m/ip/] [multihop <m/switch/]</tag>
+ <tag><label id="bfd-neighbor">neighbor <m/ip/ [dev "<m/interface/"] [local <m/ip/] [multihop <m/switch/]</tag>
BFD sessions are usually created on demand as requested by other
protocols (like OSPF or BGP). This option allows to explicitly add
a BFD session to the specified neighbor regardless of such requests.
<p>Session specific options (part of <cf/interface/ and <cf/multihop/ definitions):
<descrip>
- <tag>interval <m/time/</tag>
+ <tag><label id="bfd-interval">interval <m/time/</tag>
BFD ensures availability of the forwarding path associated with the
session by periodically sending BFD control packets in both
directions. The rate of such packets is controlled by two options,
<cf/min rx interval/ and <cf/min tx interval/ (see below). This option
is just a shorthand to set both of these options together.
- <tag>min rx interval <m/time/</tag>
+ <tag><label id="bfd-min-rx-interval">min rx interval <m/time/</tag>
This option specifies the minimum RX interval, which is announced to the
neighbor and used there to limit the neighbor's rate of generated BFD
control packets. Default: 10 ms.
- <tag>min tx interval <m/time/</tag>
+ <tag><label id="bfd-min-tx-interval">min tx interval <m/time/</tag>
This option specifies the desired TX interval, which controls the rate
of generated BFD control packets (together with <cf/min rx interval/
announced by the neighbor). Note that this value is used only if the BFD
session is up, otherwise the value of <cf/idle tx interval/ is used
instead. Default: 100 ms.
- <tag>idle tx interval <m/time/</tag>
+ <tag><label id="bfd-idle-tx-interval">idle tx interval <m/time/</tag>
In order to limit unnecessary traffic in cases where a neighbor is not
available or not running BFD, the rate of generated BFD control packets
is lower when the BFD session is not up. This option specifies the
desired TX interval in such cases instead of <cf/min tx interval/.
Default: 1 s.
- <tag>multiplier <m/num/</tag>
+ <tag><label id="bfd-multiplier">multiplier <m/num/</tag>
Failure detection time for BFD sessions is based on established rate of
BFD control packets (<cf>min rx/tx interval</cf>) multiplied by this
multiplier, which is essentially (ignoring jitter) a number of missed
multipliers could be different in each direction of a BFD session.
Default: 5.
- <tag>passive <m/switch/</tag>
+ <tag><label id="bfd-passive">passive <m/switch/</tag>
Generally, both BFD session endpoints try to establish the session by
sending control packets to the other side. This option allows to enable
passive mode, which means that the router does not send BFD packets
</descrip>
<sect1>Example
+<label id="bfd-exam">
<p><code>
protocol bfd {
<sect>BGP
+<label id="bgp">
<p>The Border Gateway Protocol is the routing protocol used for backbone level
routing in the today's Internet. Contrary to other protocols, its convergence
RFC 2545<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc2545.txt">.
<sect1>Route selection rules
+<label id="bgp-route-select-rules">
<p>BGP doesn't have any simple metric, so the rules for selection of an optimal
route among multiple BGP routes with the same preference are a bit more complex
</itemize>
<sect1>IGP routing table
+<label id="bgp-igp-routing-table">
<p>BGP is mainly concerned with global network reachability and with routes to
other autonomous systems. When such routes are redistributed to routers in the
usually one routing table used for both IGP routes and BGP routes.
<sect1>Configuration
+<label id="bgp-config">
<p>Each instance of the BGP corresponds to one neighboring router. This allows
to set routing policy and all the other parameters differently for each neighbor
using the following configuration parameters:
<descrip>
- <tag>local [<m/ip/] as <m/number/</tag>
+ <tag><label id="bgp-local">local [<m/ip/] as <m/number/</tag>
Define which AS we are part of. (Note that contrary to other IP routers,
BIRD is able to act as a router located in multiple AS'es simultaneously,
but in such cases you need to tweak the BGP paths manually in the filters
address, equivalent to the <cf/source address/ option (see below). This
parameter is mandatory.
- <tag>neighbor [<m/ip/] [port <m/number/] [as <m/number/]</tag>
+ <tag><label id="bgp-neighbor">neighbor [<m/ip/] [port <m/number/] [as <m/number/]</tag>
Define neighboring router this instance will be talking to and what AS
it is located in. In case the neighbor is in the same AS as we are, we
automatically switch to iBGP. Optionally, the remote port may also be
<cf/neighbor 10.0.0.1; neighbor as 65000;/ are valid). This parameter is
mandatory.
- <tag>interface <m/string/</tag>
+ <tag><label id="bgp-iface">interface <m/string/</tag>
Define interface we should use for link-local BGP IPv6 sessions.
Interface can also be specified as a part of <cf/neighbor address/
(e.g., <cf/neighbor fe80::1234%eth0 as 65000;/). It is an error to use
this parameter for non link-local sessions.
- <tag>direct</tag>
+ <tag><label id="bgp-direct">direct</tag>
Specify that the neighbor is directly connected. The IP address of the
neighbor must be from a directly reachable IP range (i.e. associated
with one of your router's interfaces), otherwise the BGP session
wouldn't start but it would wait for such interface to appear. The
alternative is the <cf/multihop/ option. Default: enabled for eBGP.
- <tag>multihop [<m/number/]</tag>
+ <tag><label id="bgp-multihop">multihop [<m/number/]</tag>
Configure multihop BGP session to a neighbor that isn't directly
connected. Accurately, this option should be used if the configured
neighbor IP address does not match with any local network subnets. Such
path is counted; i.e., if two BGP speakers are separated by one router,
the number of hops is 2. Default: enabled for iBGP.
- <tag>source address <m/ip/</tag>
+ <tag><label id="bgp-source-address">source address <m/ip/</tag>
Define local address we should use for next hop calculation and as a
source address for the BGP session. Default: the address of the local
end of the interface our neighbor is connected to.
- <tag>next hop self</tag>
+ <tag><label id="bgp-next-hop-self">next hop self</tag>
Avoid calculation of the Next Hop attribute and always advertise our own
source address as a next hop. This needs to be used only occasionally to
circumvent misconfigurations of other routers. Default: disabled.
- <tag>next hop keep</tag>
+ <tag><label id="bgp-next-hop-keep">next hop keep</tag>
Forward the received Next Hop attribute even in situations where the
local address should be used instead, like when the route is sent to an
interface with a different subnet. Default: disabled.
- <tag>missing lladdr self|drop|ignore</tag>
+ <tag><label id="bgp-missing-lladdr">missing lladdr self|drop|ignore</tag>
Next Hop attribute in BGP-IPv6 sometimes contains just the global IPv6
address, but sometimes it has to contain both global and link-local IPv6
addresses. This option specifies what to do if BIRD have to send both
route server (option <cf/rs client/), in that case default is <cf/ignore/,
because route servers usually do not forward packets themselves.
- <tag>gateway direct|recursive</tag>
+ <tag><label id="bgp-gateway">gateway direct|recursive</tag>
For received routes, their <cf/gw/ (immediate next hop) attribute is
computed from received <cf/bgp_next_hop/ attribute. This option
specifies how it is computed. Direct mode means that the IP address from
standard. Direct mode is simpler, does not require any routes in a
routing table, and was used in older versions of BIRD, but does not
handle well nontrivial iBGP setups and multihop. Recursive mode is
- incompatible with <ref id="dsc-sorted" name="sorted tables">. Default:
+ incompatible with <ref id="dsc-table-sorted" name="sorted tables">. Default:
<cf/direct/ for direct sessions, <cf/recursive/ for multihop sessions.
- <tag>igp table <m/name/</tag>
+ <tag><label id="bgp-igp-table">igp table <m/name/</tag>
Specifies a table that is used as an IGP routing table. Default: the
same as the table BGP is connected to.
- <tag>check link <M>switch</M></tag>
+ <tag><label id="bgp-check-link">check link <M>switch</M></tag>
BGP could use hardware link state into consideration. If enabled,
BIRD tracks the link state of the associated interface and when link
disappears (e.g. an ethernet cable is unplugged), the BGP session is
immediately shut down. Note that this option cannot be used with
multihop BGP. Default: disabled.
- <tag>bfd <M>switch</M></tag>
+ <tag><label id="bgp-bfd">bfd <M>switch</M></tag>
BGP could use BFD protocol as an advisory mechanism for neighbor
liveness and failure detection. If enabled, BIRD setups a BFD session
for the BGP neighbor and tracks its liveness by it. This has an
advantage of an order of magnitude lower detection times in case of
failure. Note that BFD protocol also has to be configured, see
- <ref id="sect-bfd" name="BFD"> section for details. Default: disabled.
+ <ref id="bfd" name="BFD"> section for details. Default: disabled.
- <tag>ttl security <m/switch/</tag>
+ <tag><label id="bgp-ttl-security">ttl security <m/switch/</tag>
Use GTSM (RFC 5082 - the generalized TTL security mechanism). GTSM
- protects against spoofed packets by ignoring received packets with a
+ protects against spoofed packets by ignoring doc/bird.sgmlreceived packets with a
smaller than expected TTL. To work properly, GTSM have to be enabled on
both sides of a BGP session. If both <cf/ttl security/ and <cf/multihop/
options are enabled, <cf/multihop/ option should specify proper hop
(ICMP protection, for example) RFC 5082 support is provided by Linux
only. Default: disabled.
- <tag>password <m/string/</tag>
+ <tag><label id="bgp-pass">password <m/string/</tag>
Use this password for MD5 authentication of BGP sessions (RFC 2385).
When used on BSD systems, see also <cf/setkey/ option below. Default:
no authentication.
- <tag>setkey <m/switch/</tag>
+ <tag><label id="bgp-setkey">setkey <m/switch/</tag>
On BSD systems, keys for TCP MD5 authentication are stored in the global
SA/SP database, which can be accessed by external utilities (e.g.
setkey(8)). BIRD configures security associations in the SA/SP database
set manually by an external utility on NetBSD and OpenBSD. Default:
enabled (ignored on non-FreeBSD).
- <tag>passive <m/switch/</tag>
+ <tag><label id="bgp-passive">passive <m/switch/</tag>
Standard BGP behavior is both initiating outgoing connections and
- accepting incoming connections. In passive mode, outgoing connections
+ accepting incoming connections. In passive modoc/bird.sgmlde, outgoing connections
are not initiated. Default: off.
- <tag>rr client</tag>
+ <tag><label id="bgp-rr-client">rr client</tag>
Be a route reflector and treat the neighbor as a route reflection
client. Default: disabled.
- <tag>rr cluster id <m/IPv4 address/</tag>
+ <tag><label id="bgp-rr-cluster-id">rr cluster id <m/IPv4 address/</tag>
Route reflectors use cluster id to avoid route reflection loops. When
there is one route reflector in a cluster it usually uses its router id
as a cluster id, but when there are more route reflectors in a cluster,
id. Clients in a cluster need not know their cluster id and this option
is not allowed for them. Default: the same as router id.
- <tag>rs client</tag>
+ <tag><label id="bgp-rs-client">rs client</tag>
Be a route server and treat the neighbor as a route server client.
A route server is used as a replacement for full mesh EBGP routing in
Internet exchange points in a similar way to route reflectors used in
example does not prepend its AS number to AS PATH attribute and keeps
MED attribute). Default: disabled.
- <tag>secondary <m/switch/</tag>
+ <tag><label id="bgp-secondary">secondary <m/switch/</tag>
Usually, if an export filter rejects a selected route, no other route is
propagated for that network. This option allows to try the next route in
order until one that is accepted is found or all routes for that network
are rejected. This can be used for route servers that need to propagate
different tables to each client but do not want to have these tables
explicitly (to conserve memory). This option requires that the connected
- routing table is <ref id="dsc-sorted" name="sorted">. Default: off.
+ routing table is <ref id="dsc-table-sorted" name="sorted">. Default: off.
- <tag>add paths <m/switch/|rx|tx</tag>
+ <tag><label id="bgp-add-paths">add paths <m/switch/|rx|tx</tag>
Standard BGP can propagate only one path (route) per destination network
(usually the selected one). This option controls the add-path protocol
extension, which allows to advertise any number of paths to a
TX direction. When active, all available routes accepted by the export
filter are advertised to the neighbor. Default: off.
- <tag>allow local as [<m/number/]</tag>
+ <tag><label id="bgp-allow-local-as">allow local as [<m/number/]</tag>
BGP prevents routing loops by rejecting received routes with the local
AS number in the AS path. This option allows to loose or disable the
check. Optional <cf/number/ argument can be used to specify the maximum
completely disabled and you should ensure loop-free behavior by some
other means. Default: 0 (no local AS number allowed).
- <tag>enable route refresh <m/switch/</tag>
+ <tag><label id="bgp-enable-route-refresh">enable route refresh <m/switch/</tag>
After the initial route exchange, BGP protocol uses incremental updates
to keep BGP speakers synchronized. Sometimes (e.g., if BGP speaker
changes its import filter, or if there is suspicion of inconsistency) it
capabilities and supports related procedures. Note that even when
disabled, BIRD can send route refresh requests. Default: on.
- <tag>graceful restart <m/switch/|aware</tag>
+ <tag><label id="bgp-graceful-restart">graceful restart <m/switch/|aware</tag>
When a BGP speaker restarts or crashes, neighbors will discard all
received paths from the speaker, which disrupts packet forwarding even
when the forwarding plane of the speaker remains intact. RFC 4724
local graceful restart requires also configuration of other protocols.
Default: aware.
- <tag>graceful restart time <m/number/</tag>
+ <tag><label id="bgp-graceful-restart-time">graceful restart time <m/number/</tag>
The restart time is announced in the BGP graceful restart capability
and specifies how long the neighbor would wait for the BGP session to
re-establish after a restart before deleting stale routes. Default:
120 seconds.
- <tag>interpret communities <m/switch/</tag>
+ <tag><label id="bgp-interpret-communities">interpret communities <m/switch/</tag>
RFC 1997 demands that BGP speaker should process well-known communities
like no-export (65535, 65281) or no-advertise (65535, 65282). For
example, received route carrying a no-adverise community should not be
disabled. In that case, similar behavior can be implemented in the
export filter. Default: on.
- <tag>enable as4 <m/switch/</tag>
+ <tag><label id="bgp-enable-as4">enable as4 <m/switch/</tag>
BGP protocol was designed to use 2B AS numbers and was extended later to
allow 4B AS number. BIRD supports 4B AS extension, but by disabling this
option it can be persuaded not to advertise it and to maintain old-style
in neighbor's implementation of 4B AS extension. Even when disabled
(off), BIRD behaves internally as AS4-aware BGP router. Default: on.
- <tag>enable extended messages <m/switch/</tag>
+ <tag><label id="bgp-enable-extended-messages">enable extended messages <m/switch/</tag>
The BGP protocol uses maximum message length of 4096 bytes. This option
provides an extension to allow extended messages with length up
to 65535 bytes. Default: off.
- <tag>capabilities <m/switch/</tag>
+ <tag><label id="bgp-capabilities">capabilities <m/switch/</tag>
Use capability advertisement to advertise optional capabilities. This is
standard behavior for newer BGP implementations, but there might be some
older BGP implementations that reject such connection attempts. When
disabled. Default: on, with automatic fallback to off when received
capability-related error.
- <tag>advertise ipv4 <m/switch/</tag>
+ <tag><label id="bgp-advertise-ipv4">advertise ipv4 <m/switch/</tag>
Advertise IPv4 multiprotocol capability. This is not a correct behavior
according to the strict interpretation of RFC 4760, but it is widespread
and required by some BGP implementations (Cisco and Quagga). This option
is relevant to IPv4 mode with enabled capability advertisement
only. Default: on.
- <tag>route limit <m/number/</tag>
+ <tag><label id="bgp-route-limit">route limit <m/number/</tag>
The maximal number of routes that may be imported from the protocol. If
the route limit is exceeded, the connection is closed with an error.
Limit is currently implemented as <cf>import limit <m/number/ action
restart</cf>. This option is obsolete and it is replaced by
- <ref id="import-limit" name="import limit option">. Default: no limit.
+ <ref id="proto-import-limit" name="import limit option">. Default: no limit.
- <tag>disable after error <m/switch/</tag>
+ <tag><label id="bgp-disable-after-error">disable after error <m/switch/</tag>
When an error is encountered (either locally or by the other side),
disable the instance automatically and wait for an administrator to fix
the problem manually. Default: off.
- <tag>hold time <m/number/</tag>
+ <tag><label id="bgp-hold-time">hold time <m/number/</tag>
Time in seconds to wait for a Keepalive message from the other side
before considering the connection stale. Default: depends on agreement
with the neighboring router, we prefer 240 seconds if the other side is
willing to accept it.
- <tag>startup hold time <m/number/</tag>
+ <tag><label id="bgp-startup-hold-time">startup hold time <m/number/</tag>
Value of the hold timer used before the routers have a chance to exchange
open messages and agree on the real value. Default: 240 seconds.
- <tag>keepalive time <m/number/</tag>
+ <tag><label id="bgp-keepalive-time">keepalive time <m/number/</tag>
Delay in seconds between sending of two consecutive Keepalive messages.
Default: One third of the hold time.
- <tag>connect delay time <m/number/</tag>
+ <tag><label id="bgp-connect-delay-time">connect delay time <m/number/</tag>
Delay in seconds between protocol startup and the first attempt to
connect. Default: 5 seconds.
- <tag>connect retry time <m/number/</tag>
+ <tag><label id="bgp-connect-retry-time">connect retry time <m/number/</tag>
Time in seconds to wait before retrying a failed attempt to connect.
Default: 120 seconds.
- <tag>error wait time <m/number/,<m/number/</tag>
+ <tag><label id="bgp-error-wait-time">error wait time <m/number/,<m/number/</tag>
Minimum and maximum delay in seconds between a protocol failure (either
local or reported by the peer) and automatic restart. Doesn't apply
when <cf/disable after error/ is configured. If consecutive errors
happen, the delay is increased exponentially until it reaches the
maximum. Default: 60, 300.
- <tag>error forget time <m/number/</tag>
+ <tag><label id="bgp-error-forget-time">error forget time <m/number/</tag>
Maximum time in seconds between two protocol failures to treat them as a
error sequence which makes <cf/error wait time/ increase exponentially.
Default: 300 seconds.
- <tag>path metric <m/switch/</tag>
+ <tag><label id="bgp-path-metric">path metric <m/switch/</tag>
Enable comparison of path lengths when deciding which BGP route is the
best one. Default: on.
- <tag>med metric <m/switch/</tag>
+ <tag><label id="bgp-med-metric">med metric <m/switch/</tag>
Enable comparison of MED attributes (during best route selection) even
between routes received from different ASes. This may be useful if all
MED attributes contain some consistent metric, perhaps enforced in
attributes are compared only if routes are received from the same AS
(which is the standard behavior). Default: off.
- <tag>deterministic med <m/switch/</tag>
+ <tag><label id="bgp-deterministic-med">deterministic med <m/switch/</tag>
BGP route selection algorithm is often viewed as a comparison between
individual routes (e.g. if a new route appears and is better than the
current best one, it is chosen as the new best one). But the proper
option enables a different (and slower) algorithm implementing proper
RFC 4271 route selection, which is deterministic. Alternative way how to
get deterministic behavior is to use <cf/med metric/ option. This option
- is incompatible with <ref id="dsc-sorted" name="sorted tables">.
+ is incompatible with <ref id="dsc-table-sorted" name="sorted tables">.
Default: off.
- <tag>igp metric <m/switch/</tag>
+ <tag><label id="bgp-igp-metric">igp metric <m/switch/</tag>
Enable comparison of internal distances to boundary routers during best
route selection. Default: on.
- <tag>prefer older <m/switch/</tag>
+ <tag><label id="bgp-prefer-older">prefer older <m/switch/</tag>
Standard route selection algorithm breaks ties by comparing router IDs.
This changes the behavior to prefer older routes (when both are external
and from different peer). For details, see RFC 5004. Default: off.
- <tag>default bgp_med <m/number/</tag>
+ <tag><label id="bgp-default-med">default bgp_med <m/number/</tag>
Value of the Multiple Exit Discriminator to be used during route
selection when the MED attribute is missing. Default: 0.
- <tag>default bgp_local_pref <m/number/</tag>
+ <tag><label id="bgp-default-local-pref">default bgp_local_pref <m/number/</tag>
A default value for the Local Preference attribute. It is used when
a new Local Preference attribute is attached to a route by the BGP
protocol itself (for example, if a route is received through eBGP and
</descrip>
<sect1>Attributes
+<label id="bgp-attr">
<p>BGP defines several route attributes. Some of them (those marked with
`<tt/I/' in the table below) are available on internal BGP connections only,
some of them (marked with `<tt/O/') are optional.
<descrip>
- <tag>bgppath <cf/bgp_path/</tag>
+ <tag><label id="rta-bgp-path">bgppath bgp_path/</tag>
Sequence of AS numbers describing the AS path the packet will travel
through when forwarded according to the particular route. In case of
internal BGP it doesn't contain the number of the local AS.
- <tag>int <cf/bgp_local_pref/ [I]</tag>
+ <tag><label id="rta-bgp-local-pref">int bgp_local_pref/ [I]</tag>
Local preference value used for selection among multiple BGP routes (see
the selection rules above). It's used as an additional metric which is
propagated through the whole local AS.
- <tag>int <cf/bgp_med/ [O]</tag>
+ <tag><label id="rta-bgp-med">int bgp_med/ [O]</tag>
The Multiple Exit Discriminator of the route is an optional attribute
which is used on external (inter-AS) links to convey to an adjacent AS
the optimal entry point into the local AS. The received attribute is
external BGP instance. See RFC 4451<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4451.txt">
for further discussion of BGP MED attribute.
- <tag>enum <cf/bgp_origin/</tag>
+ <tag><label id="rta-bgp-origin">enum bgp_origin/</tag>
Origin of the route: either <cf/ORIGIN_IGP/ if the route has originated
in an interior routing protocol or <cf/ORIGIN_EGP/ if it's been imported
from the <tt>EGP</tt> protocol (nowadays it seems to be obsolete) or
<cf/ORIGIN_INCOMPLETE/ if the origin is unknown.
- <tag>ip <cf/bgp_next_hop/</tag>
+ <tag><label id="rta-bgp-next-hop">ip bgp_next_hop/</tag>
Next hop to be used for forwarding of packets to this destination. On
internal BGP connections, it's an address of the originating router if
it's inside the local AS or a boundary router the packet will leave the
AS through if it's an exterior route, so each BGP speaker within the AS
has a chance to use the shortest interior path possible to this point.
- <tag>void <cf/bgp_atomic_aggr/ [O]</tag>
+ <tag><label id="rta-bgp-atomic-aggr">void bgp_atomic_aggr/ [O]</tag>
This is an optional attribute which carries no value, but the sole
presence of which indicates that the route has been aggregated from
multiple routes by some router on the path from the originator.
<!-- we don't handle aggregators right since they are of a very obscure type
<tag>bgp_aggregator</tag>
-->
- <tag>clist <cf/bgp_community/ [O]</tag>
+ <tag><label id="rta-bgp-community">clist bgp_community/ [O]</tag>
List of community values associated with the route. Each such value is a
pair (represented as a <cf/pair/ data type inside the filters) of 16-bit
integers, the first of them containing the number of the AS which
freedom about which community attributes it defines and what will their
semantics be.
- <tag>eclist <cf/bgp_ext_community/ [O]</tag>
+ <tag><label id="rta-bgp-ext-community">eclist bgp_ext_community/ [O]</tag>
List of extended community values associated with the route. Extended
communities have similar usage as plain communities, but they have an
extended range (to allow 4B ASNs) and a nontrivial structure with a type
field. Individual community values are represented using an <cf/ec/ data
type inside the filters.
- <tag>lclist <cf/bgp_large_community/ [O]</tag>
+ <tag><label id="rta-bgp-large-community">lclist <cf/bgp_large_community/ [O]</tag>
List of large community values associated with the route. Large BGP
communities is another variant of communities, but contrary to extended
communities they behave very much the same way as regular communities,
Individual community values are represented using an <cf/lc/ data type
inside the filters.
- <tag>quad <cf/bgp_originator_id/ [I, O]</tag>
+ <tag><label id="rta-bgp-originator-id">quad bgp_originator_id/ [I, O]</tag>
This attribute is created by the route reflector when reflecting the
route and contains the router ID of the originator of the route in the
local AS.
- <tag>clist <cf/bgp_cluster_list/ [I, O]</tag>
+ <tag><label id="rta-bgp-cluster-list">clist bgp_cluster_list/ [I, O]</tag>
This attribute contains a list of cluster IDs of route reflectors. Each
route reflector prepends its cluster ID when reflecting the route.
</descrip>
<sect1>Example
+<label id="bgp-exam">
<p><code>
protocol bgp {
<sect>Device
+<label id="device">
<p>The Device protocol is not a real routing protocol. It doesn't generate any
routes and it only serves as a module for getting information about network
interfaces to be defined for them to work with.
<sect1>Configuration
+<label id="device-config">
<p><descrip>
- <tag>scan time <m/number/</tag>
+ <tag><label id="device-scan-time">scan time <m/number/</tag>
Time in seconds between two scans of the network interface list. On
systems where we are notified about interface status changes
asynchronously (such as newer versions of Linux), we need to scan the
list only in order to avoid confusion by lost notification messages,
so the default time is set to a large value.
- <tag>primary [ "<m/mask/" ] <m/prefix/</tag>
+ <tag><label id="device-primary">primary [ "<m/mask/" ] <m/prefix/</tag>
If a network interface has more than one network address, BIRD has to
choose one of them as a primary one. By default, BIRD chooses the
lexicographically smallest address as the primary one.
<sect>Direct
+<label id="direct">
<p>The Direct protocol is a simple generator of device routes for all the
directly connected networks according to the list of interfaces provided by the
<p>There are just few configuration options for the Direct protocol:
<p><descrip>
- <tag>interface <m/pattern [, ...]/</tag>
+ <tag><label id="direct-iface">interface <m/pattern [, ...]/</tag>
By default, the Direct protocol will generate device routes for all the
interfaces available. If you want to restrict it to some subset of
interfaces or addresses (e.g. if you're using multiple routing tables
for policy routing and some of the policy domains don't contain all
- interfaces), just use this clause. See <ref id="dsc-iface" name="interface">
+ interfaces), just use this clause. See <ref id="proto-iface" name="interface">
common option for detailed description. The Direct protocol uses
extended interface clauses.
- <tag>check link <m/switch/</tag>
+ <tag><label id="direct-check-link">check link <m/switch/</tag>
If enabled, a hardware link state (reported by OS) is taken into
consideration. Routes for directly connected networks are generated only
if link up is reported and they are withdrawn when link disappears
<sect>Kernel
+<label id="krt">
<p>The Kernel protocol is not a real routing protocol. Instead of communicating
with other routers in the network, it performs synchronization of BIRD's routing
limitations can be overcome using another routing table and the pipe protocol.
<sect1>Configuration
+<label id="krt-config">
<p><descrip>
- <tag>persist <m/switch/</tag>
+ <tag><label id="krt-persist">persist <m/switch/</tag>
Tell BIRD to leave all its routes in the routing tables when it exits
(instead of cleaning them up).
- <tag>scan time <m/number/</tag>
+ <tag><label id="krt-scan-time">scan time <m/number/</tag>
Time in seconds between two consecutive scans of the kernel routing
table.
- <tag>learn <m/switch/</tag>
+ <tag><label id="krt-learn">learn <m/switch/</tag>
Enable learning of routes added to the kernel routing tables by other
routing daemons or by the system administrator. This is possible only on
systems which support identification of route authorship.
- <tag>device routes <m/switch/</tag>
+ <tag><label id="krt-device-routes">device routes <m/switch/</tag>
Enable export of device routes to the kernel routing table. By default,
such routes are rejected (with the exception of explicitly configured
device routes from the static protocol) regardless of the export filter
to protect device routes in kernel routing table (managed by OS itself)
from accidental overwriting or erasing.
- <tag>kernel table <m/number/</tag>
+ <tag><label id="krt-kernel-table">kernel table <m/number/</tag>
Select which kernel table should this particular instance of the Kernel
protocol work with. Available only on systems supporting multiple
routing tables.
- <tag>metric <m/number/</tag> (Linux)
+ <tag><label id="krt-metric">metric <m/number/</tag> (Linux)
Use specified value as a kernel metric (priority) for all routes sent to
the kernel. When multiple routes for the same network are in the kernel
routing table, the Linux kernel chooses one with lower metric. Also,
or per-route metric can be set using <cf/krt_metric/ attribute. Default:
0 (undefined).
- <tag>graceful restart <m/switch/</tag>
+ <tag><label id="krt-graceful-restart">graceful restart <m/switch/</tag>
Participate in graceful restart recovery. If this option is enabled and
a graceful restart recovery is active, the Kernel protocol will defer
synchronization of routing tables until the end of the recovery. Note
that import of kernel routes to BIRD is not affected.
- <tag>merge paths <M>switch</M> [limit <M>number</M>]</tag>
+ <tag><label id="krt-merge-paths">merge paths <M>switch</M> [limit <M>number</M>]</tag>
Usually, only best routes are exported to the kernel protocol. With path
merging enabled, both best routes and equivalent non-best routes are
merged during export to generate one ECMP (equal-cost multipath) route
</descrip>
<sect1>Attributes
+<label id="krt-attr">
<p>The Kernel protocol defines several attributes. These attributes are
translated to appropriate system (and OS-specific) route attributes. We support
these attributes:
<descrip>
- <tag>int <cf/krt_source/</tag>
+ <tag><label id="rta-krt-source">int krt_source/</tag>
The original source of the imported kernel route. The value is
system-dependent. On Linux, it is a value of the protocol field of the
route. See /etc/iproute2/rt_protos for common values. On BSD, it is
based on STATIC and PROTOx flags. The attribute is read-only.
- <tag>int <cf/krt_metric/</tag> (Linux)
+ <tag><label id="rta-krt-metric">int krt_metric/</tag> (Linux)
The kernel metric of the route. When multiple same routes are in a
kernel routing table, the Linux kernel chooses one with lower metric.
Note that preferred way to set kernel metric is to use protocol option
<cf/metric/, unless per-route metric values are needed.
- <tag>ip <cf/krt_prefsrc/</tag> (Linux)
+ <tag><label id="rta-krt-prefsrc">ip krt_prefsrc/</tag> (Linux)
The preferred source address. Used in source address selection for
outgoing packets. Has to be one of the IP addresses of the router.
- <tag>int <cf/krt_realm/</tag> (Linux)
+ <tag><label id="rta-krt-realm">int krt_realm/</tag> (Linux)
The realm of the route. Can be used for traffic classification.
- <tag>int <cf/krt_scope/</tag> (Linux IPv4)
+ <tag><label id="rta-krt-scope">int krt_scope/</tag> (Linux IPv4)
The scope of the route. Valid values are 0-254, although Linux kernel
may reject some values depending on route type and nexthop. It is
supposed to represent `indirectness' of the route, where nexthops of
<cf/krt_feature_ecn/, <cf/krt_feature_allfrag/
<sect1>Example
+<label id="krt-exam">
<p>A simple configuration can look this way:
<sect>OSPF
+<label id="ospf">
<sect1>Introduction
+<label id="ospf-intro">
<p>Open Shortest Path First (OSPF) is a quite complex interior gateway
protocol. The current IPv4 version (OSPFv2) is defined in RFC 2328
each router detects all changes.
<sect1>Configuration
+<label id="ospf-config">
<p>In the main part of configuration, there can be multiple definitions of OSPF
areas, each with a different id. These definitions includes many other switches
</code>
<descrip>
- <tag>rfc1583compat <M>switch</M></tag>
+ <tag><label id="ospf-rfc1583compat">rfc1583compat <M>switch</M></tag>
This option controls compatibility of routing table calculation with
RFC 1583 <htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc1583.txt">.
Default value is no.
- <tag>instance id <m/num/</tag>
+ <tag><label id="ospf-instance-id">instance id <m/num/</tag>
When multiple OSPF protocol instances are active on the same links, they
should use different instance IDs to distinguish their packets. Although
it could be done on per-interface basis, it is often preferred to set
interfaces of the OSPF instance. Note that this option, if used, must
precede interface definitions. Default value is 0.
- <tag>stub router <M>switch</M></tag>
+ <tag><label id="ospf-stub-router">stub router <M>switch</M></tag>
This option configures the router to be a stub router, i.e., a router
that participates in the OSPF topology but does not allow transit
traffic. In OSPFv2, this is implemented by advertising maximum metric
<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc6987.txt"> for
details. Default value is no.
- <tag>tick <M>num</M></tag>
+ <tag><label id="ospf-tick">tick <M>num</M></tag>
The routing table calculation and clean-up of areas' databases is not
performed when a single link state change arrives. To lower the CPU
utilization, it's processed later at periodical intervals of <m/num/
seconds. The default value is 1.
- <tag>ecmp <M>switch</M> [limit <M>number</M>]</tag>
+ <tag><label id="ospf-ecmp">ecmp <M>switch</M> [limit <M>number</M>]</tag>
This option specifies whether OSPF is allowed to generate ECMP
(equal-cost multipath) routes. Such routes are used when there are
several directions to the destination, each with the same (computed)
nexthops in one route. By default, ECMP is disabled. If enabled,
default value of the limit is 16.
- <tag>merge external <M>switch</M></tag>
+ <tag><label id="ospf-merge-external">merge external <M>switch</M></tag>
This option specifies whether OSPF should merge external routes from
different routers/LSAs for the same destination. When enabled together
with <cf/ecmp/, equal-cost external routes will be combined to multipath
from different LSAs are treated as separate even if they represents the
same destination. Default value is no.
- <tag>area <M>id</M></tag>
+ <tag><label id="ospf-area">area <M>id</M></tag>
This defines an OSPF area with given area ID (an integer or an IPv4
address, similarly to a router ID). The most important area is the
backbone (ID 0) to which every other area must be connected.
- <tag>stub</tag>
+ <tag><label id="ospf-stub">stub</tag>
This option configures the area to be a stub area. External routes are
not flooded into stub areas. Also summary LSAs can be limited in stub
areas (see option <cf/summary/). By default, the area is not a stub
area.
- <tag>nssa</tag>
+ <tag><label id="ospf-nssa">nssa</tag>
This option configures the area to be a NSSA (Not-So-Stubby Area). NSSA
is a variant of a stub area which allows a limited way of external route
propagation. Global external routes are not propagated into a NSSA, but
(and possibly translated and/or aggregated on area boundary). By
default, the area is not NSSA.
- <tag>summary <M>switch</M></tag>
+ <tag><label id="ospf-summary">summary <M>switch</M></tag>
This option controls propagation of summary LSAs into stub or NSSA
areas. If enabled, summary LSAs are propagated as usual, otherwise just
the default summary route (0.0.0.0/0) is propagated (this is sometimes
routers, propagating summary LSAs could lead to more efficient routing
at the cost of larger link state database. Default value is no.
- <tag>default nssa <M>switch</M></tag>
+ <tag><label id="ospf-default-nssa">default nssa <M>switch</M></tag>
When <cf/summary/ option is enabled, default summary route is no longer
propagated to the NSSA. In that case, this option allows to originate
default route as NSSA-LSA to the NSSA. Default value is no.
- <tag>default cost <M>num</M></tag>
+ <tag><label id="ospf-default-cost">default cost <M>num</M></tag>
This option controls the cost of a default route propagated to stub and
NSSA areas. Default value is 1000.
- <tag>default cost2 <M>num</M></tag>
+ <tag><label id="ospf-default-cost2">default cost2 <M>num</M></tag>
When a default route is originated as NSSA-LSA, its cost can use either
type 1 or type 2 metric. This option allows to specify the cost of a
default route in type 2 metric. By default, type 1 metric (option
<cf/default cost/) is used.
- <tag>translator <M>switch</M></tag>
+ <tag><label id="ospf-translator">translator <M>switch</M></tag>
This option controls translation of NSSA-LSAs into external LSAs. By
default, one translator per NSSA is automatically elected from area
boundary routers. If enabled, this area boundary router would
unconditionally translate all NSSA-LSAs regardless of translator
election. Default value is no.
- <tag>translator stability <M>num</M></tag>
+ <tag><label id="ospf-translator-stability">translator stability <M>num</M></tag>
This option controls the translator stability interval (in seconds).
When the new translator is elected, the old one keeps translating until
the interval is over. Default value is 40.
- <tag>networks { <m/set/ }</tag>
+ <tag><label id="ospf-networks">networks { <m/set/ }</tag>
Definition of area IP ranges. This is used in summary LSA origination.
Hidden networks are not propagated into other areas.
- <tag>external { <m/set/ }</tag>
+ <tag><label id="ospf-external">external { <m/set/ }</tag>
Definition of external area IP ranges for NSSAs. This is used for
NSSA-LSA translation. Hidden networks are not translated into external
LSAs. Networks can have configured route tag.
- <tag>stubnet <m/prefix/ { <m/options/ }</tag>
+ <tag><label id="ospf-stubnet">stubnet <m/prefix/ { <m/options/ }</tag>
Stub networks are networks that are not transit networks between OSPF
routers. They are also propagated through an OSPF area as a part of a
link state database. By default, BIRD generates a stub network record
that are subnetworks of given stub network are suppressed. This might be
used, for example, to aggregate generated stub networks.
- <tag>interface <M>pattern</M> [instance <m/num/]</tag>
+ <tag><label id="ospf-iface">interface <M>pattern</M> [instance <m/num/]</tag>
Defines that the specified interfaces belong to the area being defined.
- See <ref id="dsc-iface" name="interface"> common option for detailed
+ See <ref id="proto-iface" name="interface"> common option for detailed
description. In OSPFv2, extended interface clauses are used, because
each network prefix is handled as a separate virtual interface.
<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc6549.txt">) and is
supposed to be set per-protocol. For OSPFv3, it is an integral feature.
- <tag>virtual link <M>id</M> [instance <m/num/]</tag>
+ <tag><label id="ospf-virtual-link">virtual link <M>id</M> [instance <m/num/]</tag>
Virtual link to router with the router id. Virtual link acts as a
point-to-point interface belonging to backbone. The actual area is used
as a transport area. This item cannot be in the backbone. Like with
<cf/interface/ option, you could also use several virtual links to one
destination with different instance IDs.
- <tag>cost <M>num</M></tag>
+ <tag><label id="ospf-cost">cost <M>num</M></tag>
Specifies output cost (metric) of an interface. Default value is 10.
- <tag>stub <M>switch</M></tag>
+ <tag><label id="ospf-stub-iface">stub <M>switch</M></tag>
If set to interface it does not listen to any packet and does not send
any hello. Default value is no.
- <tag>hello <M>num</M></tag>
+ <tag><label id="ospf-hello">hello <M>num</M></tag>
Specifies interval in seconds between sending of Hello messages. Beware,
all routers on the same network need to have the same hello interval.
Default value is 10.
- <tag>poll <M>num</M></tag>
+ <tag><label id="ospf-poll">poll <M>num</M></tag>
Specifies interval in seconds between sending of Hello messages for some
neighbors on NBMA network. Default value is 20.
- <tag>retransmit <M>num</M></tag>
+ <tag><label id="ospf-retransmit">retransmit <M>num</M></tag>
Specifies interval in seconds between retransmissions of unacknowledged
updates. Default value is 5.
- <tag>priority <M>num</M></tag>
+ <tag><label id="ospf-priority">priority <M>num</M></tag>
On every multiple access network (e.g., the Ethernet) Designated Router
and Backup Designated router are elected. These routers have some special
functions in the flooding process. Higher priority increases preferences
in this election. Routers with priority 0 are not eligible. Default
value is 1.
- <tag>wait <M>num</M></tag>
+ <tag><label id="ospf-wait">wait <M>num</M></tag>
After start, router waits for the specified number of seconds between
starting election and building adjacency. Default value is 4*<m/hello/.
- <tag>dead count <M>num</M></tag>
+ <tag><label id="ospf-dead-count">dead count <M>num</M></tag>
When the router does not receive any messages from a neighbor in
<m/dead count/*<m/hello/ seconds, it will consider the neighbor down.
- <tag>dead <M>num</M></tag>
+ <tag><label id="ospf-dead">dead <M>num</M></tag>
When the router does not receive any messages from a neighbor in
<m/dead/ seconds, it will consider the neighbor down. If both directives
<cf/dead count/ and <cf/dead/ are used, <cf/dead/ has precedence.
- <tag>secondary <M>switch</M></tag>
+ <tag><label id="ospf-secondary">secondary <M>switch</M></tag>
On BSD systems, older versions of BIRD supported OSPFv2 only for the
primary IP address of an interface, other IP ranges on the interface
were handled as stub networks. Since v1.4.1, regular operation on
behavior will be changed. On Linux systems, the option is irrelevant, as
operation on non-primary addresses is already the regular behavior.
- <tag>rx buffer <M>num</M></tag>
+ <tag><label id="ospf-rx-buffer">rx buffer <M>num</M></tag>
This option allows to specify the size of buffers used for packet
processing. The buffer size should be bigger than maximal size of any
packets. By default, buffers are dynamically resized as needed, but a
fixed value could be specified. Value <cf/large/ means maximal allowed
packet size - 65535.
- <tag>tx length <M>num</M></tag>
+ <tag><label id="ospf-tx-length">tx length <M>num</M></tag>
Transmitted OSPF messages that contain large amount of information are
segmented to separate OSPF packets to avoid IP fragmentation. This
option specifies the soft ceiling for the length of generated OSPF
larger OSPF packets may still be generated if underlying OSPF messages
cannot be splitted (e.g. when one large LSA is propagated).
- <tag>type broadcast|bcast</tag>
+ <tag><label id="ospf-type-bcast">type broadcast|bcast</tag>
BIRD detects a type of a connected network automatically, but sometimes
it's convenient to force use of a different type manually. On broadcast
networks (like ethernet), flooding and Hello messages are sent using
on physically NBMA networks and on unnumbered networks (networks without
proper IP prefix).
- <tag>type pointopoint|ptp</tag>
+ <tag><label id="ospf-type-ptp">type pointopoint|ptp</tag>
Point-to-point networks connect just 2 routers together. No election is
performed and no network LSA is originated, which makes it simpler and
faster to establish. This network type is useful not only for physically
as PtP links. This network type cannot be used on physically NBMA
networks.
- <tag>type nonbroadcast|nbma</tag>
+ <tag><label id="ospf-type-nbma">type nonbroadcast|nbma</tag>
On NBMA networks, the packets are sent to each neighbor separately
because of lack of multicast capabilities. Like on broadcast networks,
a designated router is elected, which plays a central role in propagation
of LSAs. This network type cannot be used on unnumbered networks.
- <tag>type pointomultipoint|ptmp</tag>
+ <tag><label id="ospf-type-ptmp">type pointomultipoint|ptmp</tag>
This is another network type designed to handle NBMA networks. In this
case the NBMA network is treated as a collection of PtP links. This is
useful if not every pair of routers on the NBMA network has direct
communication, or if the NBMA network is used as an (possibly
unnumbered) PtP link.
- <tag>link lsa suppression <m/switch/</tag>
+ <tag><label id="ospf-link-lsa-suppression">link lsa suppression <m/switch/</tag>
In OSPFv3, link LSAs are generated for each link, announcing link-local
IPv6 address of the router to its local neighbors. These are useless on
PtP or PtMP networks and this option allows to suppress the link LSA
origination for such interfaces. The option is ignored on other than PtP
or PtMP interfaces. Default value is no.
- <tag>strict nonbroadcast <m/switch/</tag>
+ <tag><label id="ospf-strict-nonbroadcast">strict nonbroadcast <m/switch/</tag>
If set, don't send hello to any undefined neighbor. This switch is
ignored on other than NBMA or PtMP interfaces. Default value is no.
- <tag>real broadcast <m/switch/</tag>
+ <tag><label id="ospf-real-broadcast">real broadcast <m/switch/</tag>
In <cf/type broadcast/ or <cf/type ptp/ network configuration, OSPF
packets are sent as IP multicast packets. This option changes the
behavior to using old-fashioned IP broadcast packets. This may be useful
not work reliably. This is a non-standard option and probably is not
interoperable with other OSPF implementations. Default value is no.
- <tag>ptp netmask <m/switch/</tag>
+ <tag><label id="ospf-ptp-netmask">ptp netmask <m/switch/</tag>
In <cf/type ptp/ network configurations, OSPFv2 implementations should
ignore received netmask field in hello packets and should send hello
packets with zero netmask field on unnumbered PtP links. But some OSPFv2
compatibility problems related to this issue. Default value is no for
unnumbered PtP links, yes otherwise.
- <tag>check link <M>switch</M></tag>
+ <tag><label id="ospf-check-link">check link <M>switch</M></tag>
If set, a hardware link state (reported by OS) is taken into consideration.
When a link disappears (e.g. an ethernet cable is unplugged), neighbors
are immediately considered unreachable and only the address of the iface
some hardware drivers or platforms do not implement this feature.
Default value is no.
- <tag>bfd <M>switch</M></tag>
+ <tag><label id="ospf-bfd">bfd <M>switch</M></tag>
OSPF could use BFD protocol as an advisory mechanism for neighbor
liveness and failure detection. If enabled, BIRD setups a BFD session
for each OSPF neighbor and tracks its liveness by it. This has an
advantage of an order of magnitude lower detection times in case of
failure. Note that BFD protocol also has to be configured, see
- <ref id="sect-bfd" name="BFD"> section for details. Default value is no.
+ <ref id="bfd" name="BFD"> section for details. Default value is no.
- <tag>ttl security [<m/switch/ | tx only]</tag>
+ <tag><label id="ospf-ttl-security">ttl security [<m/switch/ | tx only]</tag>
TTL security is a feature that protects routing protocols from remote
spoofed packets by using TTL 255 instead of TTL 1 for protocol packets
destined to neighbors. Because TTL is decremented when packets are
set to <cf/tx only/, TTL 255 is used for sent packets, but is not
checked for received packets. Default value is no.
- <tag>tx class|dscp|priority <m/num/</tag>
+ <tag><label id="ospf-tx-class">tx class|dscp|priority <m/num/</tag>
These options specify the ToS/DiffServ/Traffic class/Priority of the
- outgoing OSPF packets. See <ref id="dsc-prio" name="tx class"> common
+ outgoing OSPF packets. See <ref id="proto-tx-class" name="tx class"> common
option for detailed description.
- <tag>ecmp weight <M>num</M></tag>
+ <tag><label id="ospf-ecmp-weight">ecmp weight <M>num</M></tag>
When ECMP (multipath) routes are allowed, this value specifies a
relative weight used for nexthops going through the iface. Allowed
values are 1-256. Default value is 1.
- <tag>authentication none</tag>
+ <tag><label id="ospf-auth-none">authentication none</tag>
No passwords are sent in OSPF packets. This is the default value.
- <tag>authentication simple</tag>
+ <tag><label id="ospf-auth-simple">authentication simple</tag>
Every packet carries 8 bytes of password. Received packets lacking this
password are ignored. This authentication mechanism is very weak.
- <tag>authentication cryptographic</tag>
+ <tag><label id="ospf-auth-cryptographic">authentication cryptographic</tag>
16-byte long MD5 digest is appended to every packet. For the digest
generation 16-byte long passwords are used. Those passwords are not sent
via network, so this mechanism is quite secure. Packets can still be
read by an attacker.
- <tag>password "<M>text</M>"</tag>
+ <tag><label id="ospf-pass">password "<M>text</M>"</tag>
An 8-byte or 16-byte password used for authentication. See
- <ref id="dsc-pass" name="password"> common option for detailed
+ <ref id="proto-pass" name="password"> common option for detailed
description.
- <tag>neighbors { <m/set/ } </tag>
+ <tag><label id="ospf-neighbors">neighbors { <m/set/ } </tag>
A set of neighbors to which Hello messages on NBMA or PtMP networks are
to be sent. For NBMA networks, some of them could be marked as eligible.
In OSPFv3, link-local addresses should be used, using global ones is
</descrip>
<sect1>Attributes
+<label id="ospf-attr">
<p>OSPF defines four route attributes. Each internal route has a <cf/metric/.
<cf/ospf_tag = 0/.
<sect1>Example
+<label id="ospf-exam">
<p><code>
protocol ospf MyOSPF {
<sect>Pipe
+<label id="pipe">
<sect1>Introduction
+<label id="pipe-intro">
<p>The Pipe protocol serves as a link between two routing tables, allowing
routes to be passed from a table declared as primary (i.e., the one the pipe is
exporting a selected subset of one table to another one.
<sect1>Configuration
+<label id="pipe-config">
<p><descrip>
- <tag>peer table <m/table/</tag>
+ <tag><label id="pipe-peer-table">peer table <m/table/</tag>
Defines secondary routing table to connect to. The primary one is
selected by the <cf/table/ keyword.
- <tag>mode opaque|transparent</tag>
+ <tag><label id="pipe-mode">mode opaque|transparent</tag>
Specifies the mode for the pipe to work in. Default is transparent.
</descrip>
<sect1>Attributes
+<label id="pipe-attr">
<p>The Pipe protocol doesn't define any route attributes.
<sect1>Example
+<label id="pipe-exam">
<p>Let's consider a router which serves as a boundary router of two different
autonomous systems, each of them connected to a subset of interfaces of the
<sect>RAdv
+<label id="radv">
<sect1>Introduction
+<label id="radv-intro">
<p>The RAdv protocol is an implementation of Router Advertisements, which are
used in the IPv6 stateless autoconfiguration. IPv6 routers send (in irregular
RFC 6106<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc6106.txt">.
<sect1>Configuration
+<label id="radv-config">
<p>There are several classes of definitions in RAdv configuration -- interface
definitions, prefix definitions and DNS definitions:
<descrip>
- <tag>interface <m/pattern [, ...]/ { <m/options/ }</tag>
+ <tag><label id="radv-iface">interface <m/pattern [, ...]/ { <m/options/ }</tag>
Interface definitions specify a set of interfaces on which the
protocol is activated and contain interface specific options.
- See <ref id="dsc-iface" name="interface"> common options for
+ See <ref id="proto-iface" name="interface"> common options for
detailed description.
- <tag>prefix <m/prefix/ { <m/options/ }</tag>
+ <tag><label id="radv-prefix">prefix <m/prefix/ { <m/options/ }</tag>
Prefix definitions allow to modify a list of advertised prefixes. By
default, the advertised prefixes are the same as the network prefixes
assigned to the interface. For each network prefix, the matching prefix
prefix definition is matching if the network prefix is a subnet of the
prefix in prefix definition.
- <tag>rdnss { <m/options/ }</tag>
+ <tag><label id="radv-rdnss">rdnss { <m/options/ }</tag>
RDNSS definitions allow to specify a list of advertised recursive DNS
servers together with their options. As options are seldom necessary,
there is also a short variant <cf>rdnss <m/address/</cf> that just
definitions may also be interface-specific when used inside interface
options. By default, interface uses both global and interface-specific
options, but that can be changed by <cf/rdnss local/ option.
-
- <tag>dnssl { <m/options/ }</tag>
+dsc-iface
+ <tag><label id="radv-dnssl">dnssl { <m/options/ }</tag>
DNSSL definitions allow to specify a list of advertised DNS search
domains together with their options. Like <cf/rdnss/ above, multiple
definitions are cumulative, they can be used also as interface-specific
options and there is a short variant <cf>dnssl <m/domain/</cf> that just
specifies one DNS search domain.
- <label id="dsc-trigger"> <tag>trigger <m/prefix/</tag>
+ <tag><label id="radv-trigger">trigger <m/prefix/</tag>
RAdv protocol could be configured to change its behavior based on
availability of routes. When this option is used, the protocol waits in
suppressed state until a <it/trigger route/ (for the specified network)
<p>Interface specific options:
<descrip>
- <tag>max ra interval <m/expr/</tag>
+ <tag><label id="radv-iface-max-ra-interval">max ra interval <m/expr/</tag>
Unsolicited router advertisements are sent in irregular time intervals.
This option specifies the maximum length of these intervals, in seconds.
Valid values are 4-1800. Default: 600
- <tag>min ra interval <m/expr/</tag>
+ <tag><label id="radv-iface-min-ra-interval">min ra interval <m/expr/</tag>
This option specifies the minimum length of that intervals, in seconds.
Must be at least 3 and at most 3/4 * <cf/max ra interval/. Default:
about 1/3 * <cf/max ra interval/.
- <tag>min delay <m/expr/</tag>
+ <tag><label id="radv-iface-min-delay">min delay <m/expr/</tag>
The minimum delay between two consecutive router advertisements, in
seconds. Default: 3
- <tag>managed <m/switch/</tag>
+ <tag><label id="radv-iface-managed">managed <m/switch/</tag>
This option specifies whether hosts should use DHCPv6 for IP address
configuration. Default: no
- <tag>other config <m/switch/</tag>
+ <tag><label id="radv-iface-other-config">other config <m/switch/</tag>
This option specifies whether hosts should use DHCPv6 to receive other
configuration information. Default: no
- <tag>link mtu <m/expr/</tag>
+ <tag><label id="radv-iface-link-mtu">link mtu <m/expr/</tag>
This option specifies which value of MTU should be used by hosts. 0
means unspecified. Default: 0
- <tag>reachable time <m/expr/</tag>
+ <tag><label id="radv-iface-reachable-time">reachable time <m/expr/</tag>
This option specifies the time (in milliseconds) how long hosts should
assume a neighbor is reachable (from the last confirmation). Maximum is
3600000, 0 means unspecified. Default 0.
- <tag>retrans timer <m/expr/</tag>
+ <tag><label id="radv-iface-retrans-timer">retrans timer <m/expr/</tag>
This option specifies the time (in milliseconds) how long hosts should
wait before retransmitting Neighbor Solicitation messages. 0 means
unspecified. Default 0.
- <tag>current hop limit <m/expr/</tag>
+ <tag><label id="radv-iface-current-hop-limit">current hop limit <m/expr/</tag>
This option specifies which value of Hop Limit should be used by
hosts. Valid values are 0-255, 0 means unspecified. Default: 64
- <tag>default lifetime <m/expr/ [sensitive <m/switch/]</tag>
+ <tag><label id="radv-iface-default-lifetime">default lifetime <m/expr/ [sensitive <m/switch/]</tag>
This option specifies the time (in seconds) how long (after the receipt
of RA) hosts may use the router as a default router. 0 means do not use
- as a default router. For <cf/sensitive/ option, see <ref id="dsc-trigger" name="trigger">.
+ as a default router. For <cf/sensitive/ option, see <ref id="radv-trigger" name="trigger">.
Default: 3 * <cf/max ra interval/, <cf/sensitive/ yes.
- <tag>default preference low|medium|high</tag>
+ <tag><label id="radv-iface-default-preference-low">default preference low|medium|high</tag>
This option specifies the Default Router Preference value to advertise
to hosts. Default: medium.
- <tag>rdnss local <m/switch/</tag>
+ <tag><label id="radv-iface-rdnss-local">rdnss local <m/switch/</tag>
Use only local (interface-specific) RDNSS definitions for this
interface. Otherwise, both global and local definitions are used. Could
also be used to disable RDNSS for given interface if no local definitons
are specified. Default: no.
- <tag>dnssl local <m/switch/</tag>
+ <tag><label id="radv-iface-dnssl-local">dnssl local <m/switch/</tag>
Use only local DNSSL definitions for this interface. See <cf/rdnss local/
option above. Default: no.
</descrip>
-<p>Prefix specific options:
+<p>Prefix specific options
<descrip>
- <tag>skip <m/switch/</tag>
+ <tag><label id="radv-prefix-skip">skip <m/switch/</tag>
This option allows to specify that given prefix should not be
advertised. This is useful for making exceptions from a default policy
of advertising all prefixes. Note that for withdrawing an already
advertised prefix it is more useful to advertise it with zero valid
lifetime. Default: no
- <tag>onlink <m/switch/</tag>
+ <tag><label id="radv-prefix-onlink">onlink <m/switch/</tag>
This option specifies whether hosts may use the advertised prefix for
onlink determination. Default: yes
- <tag>autonomous <m/switch/</tag>
+ <tag><label id="radv-prefix-autonomous">autonomous <m/switch/</tag>
This option specifies whether hosts may use the advertised prefix for
stateless autoconfiguration. Default: yes
- <tag>valid lifetime <m/expr/ [sensitive <m/switch/]</tag>
+ <tag><label id="radv-prefix-valid-lifetime">valid lifetime <m/expr/ [sensitive <m/switch/]</tag>
This option specifies the time (in seconds) how long (after the
receipt of RA) the prefix information is valid, i.e., autoconfigured
IP addresses can be assigned and hosts with that IP addresses are
considered directly reachable. 0 means the prefix is no longer
- valid. For <cf/sensitive/ option, see <ref id="dsc-trigger" name="trigger">.
+ valid. For <cf/sensitive/ option, see <ref id="radv-trigger" name="trigger">.
Default: 86400 (1 day), <cf/sensitive/ no.
- <tag>preferred lifetime <m/expr/ [sensitive <m/switch/]</tag>
+ <tag><label id="radv-prefix-preferred-lifetime">preferred lifetime <m/expr/ [sensitive <m/switch/]</tag>
This option specifies the time (in seconds) how long (after the
receipt of RA) IP addresses generated from the prefix using stateless
autoconfiguration remain preferred. For <cf/sensitive/ option,
- see <ref id="dsc-trigger" name="trigger">. Default: 14400 (4 hours),
+ see <ref id="radv-trigger" name="trigger">. Default: 14400 (4 hours),
<cf/sensitive/ no.
</descrip>
<p>RDNSS specific options:
<descrip>
- <tag>ns <m/address/</tag>
+ <tag><label id="radv-rdnss-ns">ns <m/address/</tag>
This option specifies one recursive DNS server. Can be used multiple
times for multiple servers. It is mandatory to have at least one
<cf/ns/ option in <cf/rdnss/ definition.
- <tag>lifetime [mult] <m/expr/</tag>
+ <tag><label id="radv-rdnss-lifetime">lifetime [mult] <m/expr/</tag>
This option specifies the time how long the RDNSS information may be
used by clients after the receipt of RA. It is expressed either in
seconds or (when <cf/mult/ is used) in multiples of <cf/max ra
<p>DNSSL specific options:
<descrip>
- <tag>domain <m/address/</tag>
+ <tag><label id="radv-dnssl-domain">domain <m/address/</tag>
This option specifies one DNS search domain. Can be used multiple times
for multiple domains. It is mandatory to have at least one <cf/domain/
option in <cf/dnssl/ definition.
- <tag>lifetime [mult] <m/expr/</tag>
+ <tag><label id="radv-dnssl-lifetime">lifetime [mult] <m/expr/</tag>
This option specifies the time how long the DNSSL information may be
used by clients after the receipt of RA. Details are the same as for
RDNSS <cf/lifetime/ option above. Default: 3 * <cf/max ra interval/.
<sect1>Example
+<label id="radv-exam">
<p><code>
protocol radv {
<sect>RIP
+<label id="rip">
<sect1>Introduction
+<label id="rip-intro">
<p>The RIP protocol (also sometimes called Rest In Pieces) is a simple protocol,
where each router broadcasts (to all its neighbors) distances to all networks it
pretty much obsolete. It is still usable on very small networks.
<sect1>Configuration
+<label id="rip-config">
<p>RIP configuration consists mainly of common protocol options and interface
definitions, most RIP options are interface specific.
</code>
<descrip>
- <tag>infinity <M>number</M></tag>
+ <tag><label id="rip-infinity">infinity <M>number</M></tag>
Selects the distance of infinity. Bigger values will make
protocol convergence even slower. The default value is 16.
- <tag>ecmp <M>switch</M> [limit <M>number</M>]</tag>
+ <tag><label id="rip-ecmp">ecmp <M>switch</M> [limit <M>number</M>]</tag>
This option specifies whether RIP is allowed to generate ECMP
(equal-cost multipath) routes. Such routes are used when there are
several directions to the destination, each with the same (computed)
nexthops in one route. By default, ECMP is disabled. If enabled,
default value of the limit is 16.
- <tag>interface <m/pattern [, ...]/ { <m/options/ }</tag>
+ <tag><label id="rip-iface">interface <m/pattern [, ...]/ { <m/options/ }</tag>
Interface definitions specify a set of interfaces on which the
protocol is activated and contain interface specific options.
- See <ref id="dsc-iface" name="interface"> common options for
+ See <ref id="proto-iface" name="interface"> common options for
detailed description.
</descrip>
<p>Interface specific options:
<descrip>
- <tag>metric <m/num/</tag>
+ <tag><label id="rip-iface-metric">metric <m/num/</tag>
This option specifies the metric of the interface. When a route is
received from the interface, its metric is increased by this value
before further processing. Valid values are 1-255, but values higher
than infinity has no further meaning. Default: 1.
- <tag>mode multicast|broadcast</tag>
+ <tag><label id="rip-iface-mode">mode multicast|broadcast</tag>
This option selects the mode for RIP to use on the interface. The
default is multicast mode for RIPv2 and broadcast mode for RIPv1.
RIPng always uses the multicast mode.
- <tag>passive <m/switch/</tag>
+ <tag><label id="rip-iface-passive">passive <m/switch/</tag>
Passive interfaces receive routing updates but do not transmit any
messages. Default: no.
- <tag>address <m/ip/</tag>
+ <tag><label id="rip-iface-address">address <m/ip/</tag>
This option specifies a destination address used for multicast or
broadcast messages, the default is the official RIP (224.0.0.9) or RIPng
(ff02::9) multicast address, or an appropriate broadcast address in the
broadcast mode.
- <tag>port <m/number/</tag>
+ <tag><label id="rip-iface-port">port <m/number/</tag>
This option selects an UDP port to operate on, the default is the
official RIP (520) or RIPng (521) port.
- <tag>version 1|2</tag>
+ <tag><label id="rip-iface-version">version 1|2</tag>
This option selects the version of RIP used on the interface. For RIPv1,
automatic subnet aggregation is not implemented, only classful network
routes and host routes are propagated. Note that BIRD allows RIPv1 to be
RIP, the option is not supported for RIPng, as no further versions are
defined.
- <tag>version only <m/switch/</tag>
+ <tag><label id="rip-iface-version-only">version only <m/switch/</tag>
Regardless of RIP version configured for the interface, BIRD accepts
incoming packets of any RIP version. This option restrict accepted
packets to the configured version. Default: no.
- <tag>split horizon <m/switch/</tag>
+ <tag><label id="rip-iface-split-horizon">split horizon <m/switch/</tag>
Split horizon is a scheme for preventing routing loops. When split
horizon is active, routes are not regularly propagated back to the
interface from which they were received. They are either not propagated
on the interface will not consider the router as a part of an
independent path to the destination of the route. Default: yes.
- <tag>poison reverse <m/switch/</tag>
+ <tag><label id="rip-iface-poison-reverse">poison reverse <m/switch/</tag>
When split horizon is active, this option specifies whether the poisoned
reverse variant (propagating routes back with an infinity metric) is
used. The poisoned reverse has some advantages in faster convergence,
but uses more network traffic. Default: yes.
- <tag>check zero <m/switch/</tag>
+ <tag><label id="rip-iface-check-zero">check zero <m/switch/</tag>
Received RIPv1 packets with non-zero values in reserved fields should
be discarded. This option specifies whether the check is performed or
such packets are just processed as usual. Default: yes.
- <tag>update time <m/number/</tag>
+ <tag><label id="rip-iface-update-time">update time <m/number/</tag>
Specifies the number of seconds between periodic updates. A lower number
will mean faster convergence but bigger network load. Default: 30.
- <tag>timeout time <m/number/</tag>
+ <tag><label id="rip-iface-timeout-time">timeout time <m/number/</tag>
Specifies the time interval (in seconds) between the last received route
announcement and the route expiration. After that, the network is
considered unreachable, but still is propagated with infinity distance.
Default: 180.
- <tag>garbage time <m/number/</tag>
+ <tag><label id="rip-iface-garbage-time">garbage time <m/number/</tag>
Specifies the time interval (in seconds) between the route expiration
and the removal of the unreachable network entry. The garbage interval,
when a route with infinity metric is propagated, is used for both
internal (after expiration) and external (after withdrawal) routes.
Default: 120.
- <tag>ecmp weight <m/number/</tag>
+ <tag><label id="rip-iface-ecmp-weight">ecmp weight <m/number/</tag>
When ECMP (multipath) routes are allowed, this value specifies a
relative weight used for nexthops going through the iface. Valid
values are 1-256. Default value is 1.
- <tag>authentication none|plaintext|cryptographic</tag>
+ <tag><label id="rip-iface-auth">authentication none|plaintext|cryptographic</tag>
Selects authentication method to be used. <cf/none/ means that packets
are not authenticated at all, <cf/plaintext/ means that a plaintext
password is embedded into each packet, and <cf/cryptographic/ means that
authentication to not-none, it is a good idea to add <cf>password</cf>
section. Default: none.
- <tag>password "<m/text/"</tag>
- Specifies a password used for authentication. See <ref id="dsc-pass"
+ <tag><label id="rip-iface-pass">password "<m/text/"</tag>
+ Specifies a password used for authentication. See <ref id="proto-pass"
name="password"> common option for detailed description.
- <tag>ttl security [<m/switch/ | tx only]</tag>
+ <tag><label id="rip-iface-ttl-security">ttl security [<m/switch/ | tx only]</tag>
TTL security is a feature that protects routing protocols from remote
spoofed packets by using TTL 255 instead of TTL 1 for protocol packets
destined to neighbors. Because TTL is decremented when packets are
For RIPng, TTL security is a standard behavior (required by RFC 2080)
and therefore default value is yes. For IPv4 RIP, default value is no.
- <tag>tx class|dscp|priority <m/number/</tag>
+ <tag><label id="rip-iface-tx-class">tx class|dscp|priority <m/number/</tag>
These options specify the ToS/DiffServ/Traffic class/Priority of the
- outgoing RIP packets. See <ref id="dsc-prio" name="tx class"> common
+ outgoing RIP packets. See <ref id="proto-tx-class" name="tx class"> common
option for detailed description.
- <tag>rx buffer <m/number/</tag>
+ <tag><label id="rip-iface-rx-buffer">rx buffer <m/number/</tag>
This option specifies the size of buffers used for packet processing.
The buffer size should be bigger than maximal size of received packets.
The default value is 532 for IPv4 RIP and interface MTU value for RIPng.
- <tag>tx length <m/number/</tag>
+ <tag><label id="rip-iface-tx-length">tx length <m/number/</tag>
This option specifies the maximum length of generated RIP packets. To
avoid IP fragmentation, it should not exceed the interface MTU value.
The default value is 532 for IPv4 RIP and interface MTU value for RIPng.
- <tag>check link <m/switch/</tag>
+ <tag><label id="rip-iface-check-link">check link <m/switch/</tag>
If set, the hardware link state (as reported by OS) is taken into
consideration. When the link disappears (e.g. an ethernet cable is
unplugged), neighbors are immediately considered unreachable and all
</descrip>
<sect1>Attributes
+<label id="rip-attr">
<p>RIP defines two route attributes:
<descrip>
- <tag>int <cf/rip_metric/</tag>
+ <tag><label id="rta-rip-metric">int rip_metric/</tag>
RIP metric of the route (ranging from 0 to <cf/infinity/). When routes
from different RIP instances are available and all of them have the same
preference, BIRD prefers the route with lowest <cf/rip_metric/. When a
non-RIP route is exported to RIP, the default metric is 1.
- <tag>int <cf/rip_tag/</tag>
+ <tag><label id="rta-rip-tag">int rip_tag/</tag>
RIP route tag: a 16-bit number which can be used to carry additional
information with the route (for example, an originating AS number in
case of external routes). When a non-RIP route is exported to RIP, the
</descrip>
<sect1>Example
+<label id="rip-exam">
<p><code>
protocol rip {
<sect>Static
+<label id="static">
<p>The Static protocol doesn't communicate with other routers in the network,
but instead it allows you to define routes manually. This is often used for
<p>Global options:
<descrip>
- <tag>check link <m/switch/</tag>
+ <tag><label id="static-check-link">check link <m/switch/</tag>
If set, hardware link states of network interfaces are taken into
consideration. When link disappears (e.g. ethernet cable is unplugged),
static routes directing to that interface are removed. It is possible
that some hardware drivers or platforms do not implement this feature.
Default: off.
- <tag>igp table <m/name/</tag>
+ <tag><label id="static-igp-table">igp table <m/name/</tag>
Specifies a table that is used for route table lookups of recursive
routes. Default: the same table as the protocol is connected to.
</descrip>
<p>Route definitions (each may also contain a block of per-route options):
<descrip>
- <tag>route <m/prefix/ via <m/ip/</tag>
+ <tag><label id="static-route-via-ip">route <m/prefix/ via <m/ip/</tag>
Static route through a neighboring router. For link-local next hops,
interface can be specified as a part of the address (e.g.,
<cf/via fe80::1234%eth0/).
- <tag>route <m/prefix/ multipath via <m/ip/ [weight <m/num/] [bfd <m/switch/] [via ...]</tag>
+ <tag><label id="static-route-via-mpath">route <m/prefix/ multipath via <m/ip/ [weight <m/num/] [bfd <m/switch/] [via ...]</tag>
Static multipath route. Contains several nexthops (gateways), possibly
with their weights.
- <tag>route <m/prefix/ via <m/"interface"/</tag>
+ <tag><label id="static-route-via-iface">route <m/prefix/ via <m/"interface"/</tag>
Static device route through an interface to hosts on a directly
connected network.
- <tag>route <m/prefix/ recursive <m/ip/</tag>
+ <tag><label id="static-route-recursive">route <m/prefix/ recursive <m/ip/</tag>
Static recursive route, its nexthop depends on a route table lookup for
given IP address.
- <tag>route <m/prefix/ blackhole|unreachable|prohibit</tag>
+ <tag><label id="static-route-drop">route <m/prefix/ blackhole|unreachable|prohibit</tag>
Special routes specifying to silently drop the packet, return it as
unreachable or return it as administratively prohibited. First two
targets are also known as <cf/drop/ and <cf/reject/.
<p>Per-route options:
<descrip>
- <tag>bfd <m/switch/</tag>
+ <tag><label id="static-route-bfd">bfd <m/switch/</tag>
The Static protocol could use BFD protocol for next hop liveness
detection. If enabled, a BFD session to the route next hop is created
and the static route is BFD-controlled -- the static route is announced
This option can be used for static routes with a direct next hop, or
also for for individual next hops in a static multipath route (see
above). Note that BFD protocol also has to be configured, see
- <ref id="sect-bfd" name="BFD"> section for details. Default value is no.
+ <ref id="bfd" name="BFD"> section for details. Default value is no.
- <tag><m/filter expression/</tag>
+ <tag><label id="static-route-filter"><m/filter expression/</tag>
This is a special option that allows filter expressions to be configured
on per-route basis. Can be used multiple times. These expressions are
evaluated when the route is originated, similarly to the import filter
<chapt>Conclusions
+<label id="conclusion">
<sect>Future work
+<label id="future-work">
<p>Although BIRD supports all the commonly used routing protocols, there are
still some features which would surely deserve to be implemented in future
<sect>Getting more help
+<label id="help">
<p>If you use BIRD, you're welcome to join the bird-users mailing list
(<HTMLURL URL="mailto:bird-users@network.cz" name="bird-users@network.cz">)
projects / thirdparty / bird.git / commitdiff
