[172830] in North American Network Operators' Group
BGP selection criteria in a VXR-G2 running SB code
daemon@ATHENA.MIT.EDU (Mohamed Kamal)
Fri Jul 11 10:14:15 2014
X-Original-To: nanog@nanog.org
Date: Fri, 11 Jul 2014 13:31:24 +0200
From: Mohamed Kamal <mkamal@noor.net>
To: NANOG <nanog@nanog.org>
Cc: core@noor.net
Errors-To: nanog-bounces@nanog.org
Hi,
In brief, I have a VRF configured on a PE router which is a 7200-G2
router running 12.2(31)SB18, I import two route targets, one of them
belongs to another VRF.
Now, when I receive two default routes from both VRFs, and my question
is, why did the PE router preferred the default route from
192.168.253.252:20500:0.0.0.0/0 although it's the newer one as presented
below (I have removed the RT and then added it again, so that the route
becomes the more recent)
Any ideas?
pe1#sh ip bg vpnv4 vrf network 0.0.0.0/0
BGP routing table entry for 192.168.253.210:10:0.0.0.0/0, version 43143585
Paths: (1 available, best #1, table network)
Flag: 0x420
Advertised to update-groups:
3
Local, imported path from 192.168.253.252:10:0.0.0.0/0
192.168.253.251 (metric 2010) from 192.168.253.110 (192.168.253.110)
Origin incomplete, metric 0, localpref 100, valid, internal, best
Extended Community: RT:20500:10
Originator: 192.168.253.252, Cluster list: 192.168.253.110
mpls labels in/out nolabel/719
pe1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
pe1(config)#ip vrf network
pe1(config-vrf)# route-target import 20500:20500
pe1(config-vrf)#^Z
pe1#sh ip bg vpnv4 vrf network 0.0.0.0/0
BGP routing table entry for 192.168.253.210:10:0.0.0.0/0, version 43146664
Paths: (2 available, best #1, table network)
Flag: 0x420
Advertised to update-groups:
3
Local, imported path from 192.168.253.252:20500:0.0.0.0/0
192.168.253.251 (metric 2010) from 192.168.253.110 (192.168.253.110)
Origin incomplete, metric 0, localpref 100, valid, internal, best
Extended Community: RT:20500:20500
Originator: 192.168.253.252, Cluster list: 192.168.253.110
mpls labels in/out nolabel/825
Local, imported path from 192.168.253.252:10:0.0.0.0/0
192.168.253.251 (metric 2010) from 192.168.253.110 (192.168.253.110)
Origin incomplete, metric 0, localpref 100, valid, internal
Extended Community: RT:20500:10
Originator: 192.168.253.252, Cluster list: 192.168.253.110
mpls labels in/out nolabel/719
--
Mohamed Kamal
Network Engineer, Core Team
NOOR Data Networks, SAE
City Stars Capital 5 A4
Omar Ibn El Khattab Street
Heliopolis, Cairo, Egypt
Mobile GSM.: +2 0100 29 49 691
Land Line.: +20 2 16700 Ext.: 139
Fax.: +20 2 3748 2816
Email.: mkamal@noor.net
