proto/ospf/rt.h

   1 /*
   2  *      BIRD -- OSPF
   3  *
   4  *      (c) 2000--2004 Ondrej Filip <feela@network.cz>
   5  *
   6  *      Can be freely distributed and used under the terms of the GNU GPL.
   7  *
   8  */
   9
  10 #ifndef _BIRD_OSPF_RT_H_
  11 #define _BIRD_OSPF_RT_H_
  12
  13 #define ORT_UNDEF -1
  14 #define ORT_ROUTER 1
  15 #define ORT_NET 0
  16
  17 typedef struct orta
  18 {
  19   u8 type;                      /* RTS_OSPF_* */
  20   u8 nhs_reuse;                 /* Whether nhs nodes can be reused during merging */
  21   u32 options;
  22   /*
  23    * For ORT_ROUTER routes, options field are router-LSA style
  24    * options, with V,E,B bits. In OSPFv2, ASBRs from another areas
  25    * (that we know from rt-summary-lsa) have just ORTA_ASBR in
  26    * options, their real options are unknown.
  27    */
  28 #define ORTA_ASBR OPT_RT_E
  29 #define ORTA_ABR  OPT_RT_B
  30   /*
  31    * For ORT_NET routes, the field is almost unused with one
  32    * exception: ORTA_PREF for external routes means that the route is
  33    * preferred in AS external route selection according to 16.4.1. -
  34    * it is intra-area path using non-backbone area. In other words,
  35    * the forwarding address (or ASBR if forwarding address is zero) is
  36    * intra-area (type == RTS_OSPF) and its area is not a backbone.
  37    */
  38 #define ORTA_PREF 0x80000000
  39 #define ORTA_NSSA 0x40000000
  40 #define ORTA_PROP 0x20000000
  41
  42   u32 metric1;
  43   u32 metric2;
  44   u32 tag;
  45   u32 rid;                      /* Router ID of real advertising router */
  46   struct ospf_area *oa;
  47   struct ospf_area *voa;        /* Used when route is replaced in ospf_rt_sum_tr(),
  48                                    NULL otherwise */
  49   struct mpnh *nhs;             /* Next hops computed during SPF */
  50   struct top_hash_entry *en;    /* LSA responsible for this orta */
  51 }
  52 orta;
  53
  54 typedef struct ort
  55 {
  56   /*
  57    * We use fn.x0 to mark persistent rt entries, that are needed for summary
  58    * LSAs that don't have 'proper' rt entry (area networks + default to stubs)
  59    * to keep uid stable (used for LSA ID in OSPFv3 - see fibnode_to_lsaid()).
  60    *
  61    * We use fn.x1 to note whether the external route was originated
  62    * from the route export (in ospf_rt_notify()) or from the NSSA
  63    * route translation (in check_nssa_lsa()).
  64    *
  65    * old_* values are here to represent the last route update. old_rta
  66    * is cached (we keep reference), mainly for multipath nexthops.
  67    * old_rta == NULL means route wasn not in the last update, in that
  68    * case other old_* values are not valid.
  69    */
  70   struct fib_node fn;
  71   orta n;
  72   u32 old_metric1, old_metric2, old_tag, old_rid;
  73   rta *old_rta;
  74 }
  75 ort;
  76
  77 static inline int rt_is_nssa(ort *nf)
  78 { return nf->n.options & ORTA_NSSA; }
  79
  80 #define EXT_EXPORT 1
  81 #define EXT_NSSA 2
  82
  83 /*
  84  * Invariants for structs top_hash_entry (nodes of LSA db)
  85  * enforced by SPF calculation for final nodes (color == INSPF):
  86  * - only router, network and AS-external LSAs
  87  * - lsa.age < LSA_MAXAGE
  88  * - dist < LSINFINITY (or 2*LSINFINITY for ext-LSAs)
  89  * - nhs is non-NULL unless the node is oa->rt (calculating router itself)
  90  * - beware, nhs is not valid after SPF calculation
  91  *
  92  * Invariants for structs orta nodes of fib tables po->rtf, oa->rtr:
  93  * - nodes may be invalid (fn.type == 0), in that case other invariants don't hold
  94  * - n.metric1 may be at most a small multiple of LSINFINITY,
  95  *   therefore sums do not overflow
  96  * - n.oa is always non-NULL
  97  * - n.nhs is always non-NULL unless it is configured stubnet
  98  * - n.en is non-NULL for external routes, NULL for intra/inter area routes.
  99  * - oa->rtr does not contain calculating router itself
 100  *
 101  * There are four types of nexthops in nhs fields:
 102  * - gateway nexthops (non-NULL iface, gw != IPA_NONE)
 103  * - device nexthops (non-NULL iface, gw == IPA_NONE)
 104  * - dummy vlink nexthops (NULL iface, gw == IPA_NONE)
 105  * - configured stubnets (nhs is NULL, only RTS_OSPF orta nodes in po->rtf)
 106  *
 107  * Dummy vlink nexthops and configured stubnets cannot be mixed with
 108  * regular ones, nhs field contains either list of gateway+device nodes,
 109  * one vlink node, or NULL for configured stubnet.
 110  *
 111  * Dummy vlink nexthops can appear in both network (rtf) and backbone area router
 112  * (rtr) tables for regular and inter-area routes, but only if areano > 1. They are
 113  * replaced in ospf_rt_sum_tr() and removed in ospf_rt_abr1(), therefore cannot
 114  * appear in ASBR pre-selection and external routes processing.
 115  */
 116
 117 void ospf_rt_spf(struct proto_ospf *po);
 118 void ospf_rt_initort(struct fib_node *fn);
 119
 120
 121 #endif /* _BIRD_OSPF_RT_H_ */