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| author | Ondrej Zajicek <santiago@crfreenet.org> | 2008-10-26 22:59:21 +0100 |
|---|---|---|
| committer | Ondrej Zajicek <santiago@crfreenet.org> | 2008-10-26 22:59:21 +0100 |
| commit | b6bf284a905412cfe107b4967e55649e6194187e (patch) | |
| tree | f0098a6d05a72982c6cd9f7e85c195b8a4861b94 /proto/bgp/attrs.c | |
| parent | 4819c3e17ac22c6810ee80261ac3bffb5127e39d (diff) | |
| download | bird-b6bf284a905412cfe107b4967e55649e6194187e.tar bird-b6bf284a905412cfe107b4967e55649e6194187e.zip | |
Bugfixes in MULIT_EXIT_DISC attribute handling.
- Old MED handling was completely different from behavior
specified in RFCs - for example they havn't been propagated
to neighboring areas.
- Update tie-breaking according to RFC 4271.
- Change default value for 'default bgp_med' configuration
option according to RFC 4271.
Diffstat (limited to 'proto/bgp/attrs.c')
| -rw-r--r-- | proto/bgp/attrs.c | 46 |
1 files changed, 36 insertions, 10 deletions
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c index b5d8fba..2210cbe 100644 --- a/proto/bgp/attrs.c +++ b/proto/bgp/attrs.c @@ -146,7 +146,7 @@ static struct attr_desc bgp_attr_table[] = { bgp_check_as_path, NULL }, { "next_hop", 4, BAF_TRANSITIVE, EAF_TYPE_IP_ADDRESS, 1, /* BA_NEXT_HOP */ bgp_check_next_hop, NULL }, - { "med", 4, BAF_OPTIONAL, EAF_TYPE_INT, 0, /* BA_MULTI_EXIT_DISC */ + { "med", 4, BAF_OPTIONAL, EAF_TYPE_INT, 1, /* BA_MULTI_EXIT_DISC */ NULL, NULL }, { "local_pref", 4, BAF_TRANSITIVE, EAF_TYPE_INT, 0, /* BA_LOCAL_PREF */ NULL, NULL }, @@ -829,7 +829,17 @@ bgp_update_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p eattr *a; if (!p->is_internal) - bgp_path_prepend(e, attrs, pool, p->local_as); + { + bgp_path_prepend(e, attrs, pool, p->local_as); + + /* The MULTI_EXIT_DISC attribute received from a neighboring AS MUST NOT be + * propagated to other neighboring ASes. + * Perhaps it would be better to undefine it. + */ + a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); + if (a) + bgp_attach_attr(attrs, pool, BA_MULTI_EXIT_DISC, 0); + } a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP)); if (a && (p->is_internal || (!p->is_internal && e->attrs->iface == p->neigh->iface))) @@ -894,6 +904,18 @@ bgp_import_control(struct proto *P, rte **new, ea_list **attrs, struct linpool * return bgp_create_attrs(p, e, attrs, pool); } +static inline u32 +bgp_get_neighbor(rte *r) +{ + eattr *e = ea_find(r->attrs->eattrs, EA_CODE(EAP_BGP, BA_AS_PATH)); + u32 as; + + if (e && as_path_get_last(e->u.ptr, &as)) + return as; + else + return ((struct bgp_proto *) r->attrs->proto)->remote_as; +} + int bgp_rte_better(rte *new, rte *old) { @@ -936,14 +958,18 @@ bgp_rte_better(rte *new, rte *old) return 0; /* RFC 4271 9.1.2.2. c) Compare MED's */ - x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); - y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); - n = x ? x->u.data : new_bgp->cf->default_med; - o = y ? y->u.data : old_bgp->cf->default_med; - if (n < o) - return 1; - if (n > o) - return 0; + + if (bgp_get_neighbor(new) == bgp_get_neighbor(old)) + { + x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); + y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC)); + n = x ? x->u.data : new_bgp->cf->default_med; + o = y ? y->u.data : old_bgp->cf->default_med; + if (n < o) + return 1; + if (n > o) + return 0; + } /* RFC 4271 9.1.2.2. d) Prefer external peers */ if (new_bgp->is_internal > old_bgp->is_internal) |