Traceroute results different than show ip bgp

[sandevsingh]

Hi, our company has multiple sites and are all connected by MPLS by a service provider. If I do a traceroute and show ip bgp for an ip present in a different site, i see different results - (Please note the difference in AS numbers). Why is this so? 

###### show ip bgp results #######

RTR1#show ip bgp 10.97.47.192

BGP routing table entry for 10.97.46.0/23, version 2020

Paths: (1 available, best #1, table default)

  Advertised to update-groups:

     2        

  65506 852 65508 64970, (received & used)

    10.97.41.1 from 10.97.41.1 (10.52.140.135)

      Origin IGP, localpref 200, valid, external, best

######## traceroute results #########

RTR1#trace 10.97.47.192

Type escape sequence to abort.

Tracing the route to 10.97.47.192

VRF info: (vrf in name/id, vrf out name/id)

  1 10.97.41.1 8 msec 4 msec 0 msec

  2 10.143.36.90 [AS 64952] 8 msec 0 msec 4 msec

  3 10.54.83.118 [AS 64952] 28 msec 36 msec 32 msec

  4 10.54.83.117 [AS 64952] 28 msec 32 msec 28 msec

  5  *  *  *

  6  *  *

Why is this happening?

[milan.kulik]

Hi,

look at the P-router part in these nice documents:

https://www.packetmischief.ca/2015/05/04/walking-with-packets-traceroute-through-mpls-cloud/

http://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/26585-mpls-traceroute.html

I believe those AS  numbers displayed are not coming within the ICMP TTL-expired packets.

They are probably just added by the Cisco router on which you issued the traceroute command.

Can you just check which AS numbers belong to the IP addresses listed in your traceroute output?

Best regards,

Milan