BGP selection criteria in a VXR-G2 running SB code

Mohamed Kamal mkamal at noor.net
Fri Jul 11 11:31:24 UTC 2014


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 at noor.net




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