mirror/labs-bird
1
0
Fork 0
mirror of https://gitlab.labs.nic.cz/labs/bird.git synced 2024-05-11 16:54:54 +00:00
Code Releases Activity

Adds BGP option related to MED handling.

Browse Source 
Adds option 'med metric' allows to compare MEDs
between routes received from different neighbors.
This commit is contained in:
Ondrej Zajicek
2011-04-22 16:13:27 +02:00
parent 71ca77169d
commit 73272f04af
4 changed files with 34 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
proto/bgp/attrs.c
View File

@@ -1118,7 +1118,17 @@ 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))
/* This is noncompliant. Proper RFC 4271 path selection cannot be
* interpreted as finding the best path in some ordering.
* Therefore, it cannot be implemented in BIRD without some ugly
* hacks. This is just an approximation, which in specific
* situations may lead to persistent routing loops, because it is
* nondeterministic - it depends on the order in which routes
* appeared. But it is also the same behavior as used by default in
* Cisco routers, so it is probably not a big issue.
*/
if (new_bgp->cf->med_metric || old_bgp->cf->med_metric ||
(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));

1
proto/bgp/bgp.h
View File

@@ -25,6 +25,7 @@ struct bgp_config {
int missing_lladdr; /* What we will do when we don' know link-local addr, see MLL_* */
int gw_mode; /* How we compute route gateway from next_hop attr, see GW_* */
int compare_path_lengths; /* Use path lengths when selecting best route */
int med_metric; /* Compare MULTI_EXIT_DISC even between routes from differen ASes */
int igp_metric; /* Use IGP metrics when selecting best route */
int prefer_older; /* Prefer older routes according to RFC 5004 */
u32 default_local_pref; /* Default value for LOCAL_PREF attribute */

3
proto/bgp/config.Y
View File

@@ -25,7 +25,7 @@ CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY,
ADVERTISE, IPV4, CAPABILITIES, LIMIT, PASSIVE, PREFER, OLDER,
MISSING, LLADDR, DROP, IGNORE, ROUTE, REFRESH, INTERPRET,
COMMUNITIES, BGP_ORIGINATOR_ID, BGP_CLUSTER_LIST, IGP, TABLE,
GATEWAY, DIRECT, RECURSIVE)
GATEWAY, DIRECT, RECURSIVE, MED)
CF_GRAMMAR
@@ -79,6 +79,7 @@ bgp_proto:
| bgp_proto GATEWAY DIRECT ';' { BGP_CFG->gw_mode = GW_DIRECT; }
| bgp_proto GATEWAY RECURSIVE ';' { BGP_CFG->gw_mode = GW_RECURSIVE; }
| bgp_proto PATH METRIC bool ';' { BGP_CFG->compare_path_lengths = $4; }
| bgp_proto MED METRIC bool ';' { BGP_CFG->med_metric = $4; }
| bgp_proto IGP METRIC bool ';' { BGP_CFG->igp_metric = $4; }
| bgp_proto PREFER OLDER bool ';' { BGP_CFG->prefer_older = $4; }
| bgp_proto DEFAULT BGP_MED expr ';' { BGP_CFG->default_med = $4; }