diff options
Diffstat (limited to 'proto/ospf/topology.h')
| -rw-r--r-- | proto/ospf/topology.h | 118 |
1 files changed, 110 insertions, 8 deletions
diff --git a/proto/ospf/topology.h b/proto/ospf/topology.h index e4ea79f7..b34689e2 100644 --- a/proto/ospf/topology.h +++ b/proto/ospf/topology.h @@ -18,7 +18,7 @@ struct top_hash_entry in intra-area routing table calculation */ struct top_hash_entry *next; /* Next in hash chain */ struct ospf_lsa_header lsa; - u16 lsa_type; /* lsa.type processed and converted to common values */ + u16 lsa_type; /* lsa.type processed and converted to common values (LSA_T_*) */ u16 init_age; /* Initial value for lsa.age during inst_time */ u32 domain; /* Area ID for area-wide LSAs, Iface ID for link-wide LSAs */ // struct ospf_area *oa; @@ -37,13 +37,115 @@ struct top_hash_entry #define OUTSPF 0 #define CANDIDATE 1 #define INSPF 2 - u8 rtcalc; /* LSA generated during RT calculation (LSA_RTCALC or LSA_STALE)*/ + u8 mode; /* LSA generated during RT calculation (LSA_RTCALC or LSA_STALE)*/ u8 nhs_reuse; /* Whether nhs nodes can be reused during merging. See a note in rt.c:merge_nexthops() */ }; -#define LSA_RTCALC 1 -#define LSA_STALE 2 + +/* Prevents ospf_hash_find() to ignore the entry, for p->lsrqh and p->lsrth */ +#define LSA_BODY_DUMMY ((void *) 1) + +/* + * LSA entry life cycle + * + * LSA entries are created by ospf_originate_lsa() (for locally originated LSAs) + * or ospf_install_lsa() (for LSAs received from neighbors). A regular (like + * newly originated) LSA entry has defined lsa_body nad lsa.age < %LSA_MAXAGE. + * When the LSA is requested to be flushed by ospf_flush_lsa(), the lsa.age is + * set to %LSA_MAXAGE and flooded. Flush process is finished asynchronously, + * when (at least) flooding is acknowledged by neighbors. This is detected in + * ospf_update_lsadb(), then ospf_clear_lsa() is called to free the LSA body but + * the LSA entry is kept. Such LSA does not formally exist, we keep an empty + * entry (until regular timeout) to know inst_time and lsa.sn in the case of + * later reorigination. After the timeout, LSA is removed by ospf_remove_lsa(). + * + * When LSA origination is requested (by ospf_originate_lsa()). but it is not + * possible to do that immediately (because of MinLSInterval or because the + * sequence number is wrapping), The new LSA is scheduled for later origination + * in next_lsa_* fields of the LSA entry. The later origination is handled by + * ospf_originate_next_lsa() called from ospf_update_lsadb(). We can see that + * both real origination and final flush is asynchronous to ospf_originate_lsa() + * and ospf_flush_lsa(). + * + * LSA entry therefore could be in three basic states: + * R - regular (lsa.age < %LSA_MAXAGE, lsa_body != NULL) + * F - flushing (lsa.age == %LSA_MAXAGE, lsa_body != NULL) + * E - empty (lsa.age == %LSA_MAXAGE, lsa_body == NULL) + * + * And these states are doubled based on whether the next LSA is scheduled + * (next_lsa_body != NULL, -n suffix) or not (next_lsa_body == NULL). We also + * use X for a state of non-existentce. We have this basic state graph + * (transitions from any state to R are omitted for clarity): + * + * X --> R ---> F ---> E --> X + * | \ / | | + * | \/ | | + * | /\ | | + * | / \ | | + * Rn --> Fn --> En + * + * The transitions are: + * + * any state -> R - new LSA origination requested and executed + * R -> Rn, F -> Fn, E -> En - new LSA origination requested and postponed + * R -> Fn - new LSA origination requested, seqnum wrapping + * Rn,Fn,En -> R - postponed LSA finally originated + * R -> R - LSA refresh done + * R -> Fn - LSA refresh with seqnum wrapping + * R -> F, Rn -> Fn - LSA age timeout + * R,Rn,Fn -> F, En -> E - LSA flush requested + * F -> E, Fn -> En - LSA flush done (acknowledged) + * E -> X - LSA real age timeout (or immediate for received LSA) + * + * The 'origination requested' and 'flush requested' transitions are triggered + * and done by ospf_originate_lsa() and ospf_flush_lsa(), the rest is handled + * asynchronously by ospf_update_lsadb(). + * + * The situation is significantly simpler for non-local (received) LSAs - there + * is no postponed origination and after flushing is done, LSAs are immediately + * removed, so it is just X -> R -> F -> X, or X -> F -> X (when MaxAge LSA is + * received). + * + * There are also some special cases related to handling of received unknown + * self-originated LSAs in ospf_advance_lsa(): + * X -> F - LSA is received and immediately flushed + * R,Rn -> Fn - LSA with MaxSeqNo received and flushed, current LSA scheduled + */ + + +#define LSA_M_BASIC 0 +#define LSA_M_EXPORT 1 +#define LSA_M_RTCALC 2 +#define LSA_M_STALE 3 + +/* + * LSA entry modes: + * + * LSA_M_BASIC - The LSA is explicitly originated using ospf_originate_lsa() and + * explicitly flushed using ospf_flush_lsa(). When the LSA is changed, the + * routing table calculation is scheduled. This is also the mode used for LSAs + * received from neighbors. Example: Router-LSAs, Network-LSAs. + * + * LSA_M_EXPORT - like LSA_M_BASIC, but the routing table calculation does not + * depend on the LSA. Therefore, the calculation is not scheduled when the LSA + * is changed. Example: AS-external-LSAs for exported routes. + * + * LSA_M_RTCALC - The LSA has to be requested using ospf_originate_lsa() during + * each routing table calculation, otherwise it is flushed automatically at the + * end of the calculation. The LSA is a result of the calculation and not a + * source for it. Therefore, the calculation is not scheduled when the LSA is + * changed. Example: Summary-LSAs. + * + * LSA_M_STALE - Temporary state for LSA_M_RTCALC that is not requested during + * the current routing table calculation. + * + * + * Note that we do not schedule the routing table calculation when the age of + * LSA_M_BASIC LSA is changed to MaxAge because of the sequence number wrapping, + * As it will be switched back to a regular one ASAP. + */ + struct top_graph { @@ -61,6 +163,7 @@ struct top_graph struct ospf_new_lsa { u16 type; + u8 mode; u32 dom; u32 id; u16 opts; @@ -69,9 +172,8 @@ struct ospf_new_lsa struct ort *nf; }; -struct top_graph *ospf_top_new(pool *); -void ospf_top_free(struct top_graph *); -void ospf_top_dump(struct top_graph *, struct proto *); +struct top_graph *ospf_top_new(struct ospf_proto *p, pool *pool); +void ospf_top_free(struct top_graph *f); struct top_hash_entry * ospf_install_lsa(struct ospf_proto *p, struct ospf_lsa_header *lsa, u32 type, u32 domain, void *body); struct top_hash_entry * ospf_originate_lsa(struct ospf_proto *p, struct ospf_new_lsa *lsa); @@ -84,7 +186,7 @@ static inline void ospf_flush2_lsa(struct ospf_proto *p, struct top_hash_entry * void ospf_originate_sum_net_lsa(struct ospf_proto *p, struct ospf_area *oa, ort *nf, int metric); void ospf_originate_sum_rt_lsa(struct ospf_proto *p, struct ospf_area *oa, ort *nf, int metric, u32 options); -void ospf_originate_ext_lsa(struct ospf_proto *p, struct ospf_area *oa, ort *nf, u8 rtcalc, u32 metric, u32 ebit, ip_addr fwaddr, u32 tag, int pbit); +void ospf_originate_ext_lsa(struct ospf_proto *p, struct ospf_area *oa, ort *nf, u8 mode, u32 metric, u32 ebit, ip_addr fwaddr, u32 tag, int pbit); void ospf_rt_notify(struct proto *P, rtable *tbl, net *n, rte *new, rte *old, ea_list *attrs); void ospf_update_topology(struct ospf_proto *p); |