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-rw-r--r--proto/bgp/attrs.c10
-rw-r--r--proto/bgp/bgp.h1
-rw-r--r--proto/bgp/config.Y3
3 files changed, 11 insertions, 3 deletions
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index d839ed0..9c7bc30 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -1044,7 +1044,6 @@ bgp_rte_better(rte *new, rte *old)
return 0;
/* RFC 4271 9.1.2.2. c) Compare MED's */
-
if (bgp_get_neighbor(new) == bgp_get_neighbor(old))
{
x = ea_find(new->attrs->eattrs, EA_CODE(EAP_BGP, BA_MULTI_EXIT_DISC));
@@ -1082,12 +1081,19 @@ bgp_rte_better(rte *new, rte *old)
y = ea_find(old->attrs->eattrs, EA_CODE(EAP_BGP, BA_ORIGINATOR_ID));
n = x ? x->u.data : new_bgp->remote_id;
o = y ? y->u.data : old_bgp->remote_id;
+
+ /* RFC 5004 - prefer older routes */
+ /* (if both are external and from different peer) */
+ if ((new_bgp->cf->prefer_older || old_bgp->cf->prefer_older) &&
+ !new_bgp->is_internal && n != o)
+ return 0;
+
+ /* rest of RFC 4271 9.1.2.2. f) */
if (n < o)
return 1;
if (n > o)
return 0;
-
/* RFC 4271 9.1.2.2. g) Compare peer IP adresses */
return (ipa_compare(new_bgp->cf->remote_ip, old_bgp->cf->remote_ip) < 0);
}
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index 0a82be2..c487aaf 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -24,6 +24,7 @@ struct bgp_config {
ip_addr source_addr; /* Source address to use */
int next_hop_self; /* Always set next hop to local IP address */
int compare_path_lengths; /* Use path lengths when selecting best route */
+ int prefer_older; /* Prefer older routes according to RFC 5004 */
u32 default_local_pref; /* Default value for LOCAL_PREF attribute */
u32 default_med; /* Default value for MULTI_EXIT_DISC attribute */
int capabilities; /* Enable capability handshake [RFC3392] */
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index 7360820..9401175 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -22,7 +22,7 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
BGP_PATH, BGP_LOCAL_PREF, BGP_MED, BGP_ORIGIN, BGP_NEXT_HOP,
BGP_ATOMIC_AGGR, BGP_AGGREGATOR, BGP_COMMUNITY, SOURCE, ADDRESS,
PASSWORD, RR, RS, CLIENT, CLUSTER, ID, AS4, ADVERTISE, IPV4,
- CAPABILITIES, LIMIT, PASSIVE)
+ CAPABILITIES, LIMIT, PASSIVE, PREFER, OLDER)
CF_GRAMMAR
@@ -65,6 +65,7 @@ bgp_proto:
| bgp_proto MULTIHOP expr VIA ipa ';' { BGP_CFG->multihop = $3; BGP_CFG->multihop_via = $5; }
| bgp_proto NEXT HOP SELF ';' { BGP_CFG->next_hop_self = 1; }
| bgp_proto PATH METRIC bool ';' { BGP_CFG->compare_path_lengths = $4; }
+ | bgp_proto PREFER OLDER bool ';' { BGP_CFG->prefer_older = $4; }
| bgp_proto DEFAULT BGP_MED expr ';' { BGP_CFG->default_med = $4; }
| bgp_proto DEFAULT BGP_LOCAL_PREF expr ';' { BGP_CFG->default_local_pref = $4; }
| bgp_proto SOURCE ADDRESS ipa ';' { BGP_CFG->source_addr = $4; }