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-rw-r--r--proto/bgp/attrs.c46
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)