sh ip bgp not showing routes learned from both MPLS carriers

[afgitdepartment]

Hello,

I am building a network in a lab envrionment to mimic a new production configuration we are implementing. I don't know if this is the normal way show ip bgp displays the paths to a network.

See attached pdf for a diagram of the network.

my issues is if advertise 10.128.3.0/24 network from FMT-SWITCH-1 and that prefix goes out to both MPLS providers and is then received by

GDC-ROUTER-3 and GDC-ROUTER-4. 

If I go to GDC-SWITCH-1 and look at the output of show ip bgp 10.128.3.0/24, I only see the path's that point to one MPLS carrier:

GDC-SWITCH-1#sh ip bgp vpnv4 VRf VPN_A 10.128.3.0 255.255.255.0

BGP routing table entry for 64770:30:10.128.3.0/24, version 447

Paths: (2 available, best #1, table VPN_A)

Multipath: eiBGP

  Not advertised to any peer

  209 65534

    10.99.8.50 (metric 409600) from 10.99.8.50 (169.254.0.1)          GDC-ROUTER-4

      Origin IGP, metric 0, localpref 110, valid, internal, best

      Extended Community: RT:64770:300

      mpls labels in/out 37/nolabel

  209 65534, (received-only)

    10.99.8.50 (metric 409600) from 10.99.8.50 (169.254.0.1)          GDC-ROUTER-4

      Origin IGP, metric 0, localpref 110, valid, internal

      mpls labels in/out 37/nolabel

Should I also see the paths that are being received from GDC-ROUTER-3 as well? 

I can provide more detail if necessary.

thank you,

Matt.

[shillings]

I'm a bit rusty, but as no one else has responded, thought I'd try to help.

Please confirm that GDC-ROUTER-3 is definitely advertising the 10.128.3.0/24 prefix out to the GDC-SWITCH-1 neighbor?

Is either device filtering prefixes at the moment, and in which direction?

I'm presuming the BGP neighborship is established between GDC-ROUTER-3 and GDC-SWITCH-1

[Giuseppe Larosa]

Hello Matt,

you have manipulated the Local preference BGP attribute that is 110 somewhere in your setup.

As a result of this manipulation the best path choice performed by GDC-ROUTER-4 has propagated in the whole AS. If GDC-ROUTER-3 prefers the route coming on iBGP from GDC-ROUTER-4 it will avoid to advertise the other eBGP advertisement.

I think this is what is happening here.

Hope to help

Giuseppe