BGP not advertising connected routes

[steve martin]

Hello,

Our old   mpls is being cut off tonight, but when I completed a test our secondary datacentre doesn’t advertised the connected route at that site, can you give me some advice. The bgp config is below.  Have you any ideas why the connected routes won’t advertise – they are below the config.  The denysubnet prefix-list is to there to stop them being learnt again from the old mpls, but they aren’t being advertised.  The prefix-list is below also.

10.16.159.58 is the old mpls,  10.16.159.154 is the new one.

Many thanks,

address-family ipv4 vrf INSIDE

  bgp router-id 46.183.194.254

  redistribute connected

neighbor 10.16.159.58 remote-as 65001

  neighbor 10.16.159.58 description Peering To RMBC-CORP

  neighbor 10.16.159.58 timers 30 60

  neighbor 10.16.159.58 activate

  neighbor 10.16.159.58 allowas-in

  neighbor 10.16.159.58 soft-reconfiguration inbound

  neighbor 10.16.159.154 remote-as 64600

  neighbor 10.16.159.154 description link to BT

  neighbor 10.16.159.154 activate

  neighbor 10.16.159.154 prefix-list denysubnets in

C        10.16.18.0/24 is directly connected, Vlan518

L        10.16.18.254/32 is directly connected, Vlan518

C        10.16.128.0/23 is directly connected, Vlan3128

L        10.16.129.254/32 is directly connected, Vlan3128

C        10.16.130.0/23 is directly connected, Vlan3130

L        10.16.131.254/32 is directly connected, Vlan3130

C        10.16.132.0/24 is directly connected, Vlan3132

L        10.16.132.254/32 is directly connected, Vlan3132

C        10.16.133.0/24 is directly connected, Vlan3133

L        10.16.133.254/32 is directly connected, Vlan3133

C        10.16.134.0/24 is directly connected, Vlan3134

L        10.16.134.253/32 is directly connected, Vlan3134

C        10.16.144.0/23 is directly connected, Vlan3144

L        10.16.145.251/32 is directly connected, Vlan3144

C        10.16.159.4/30 is directly connected, GigabitEthernet1/0/3

L        10.16.159.5/32 is directly connected, GigabitEthernet1/0/3

C        10.16.159.12/30 is directly connected, GigabitEthernet1/0/4

L        10.16.159.13/32 is directly connected, GigabitEthernet1/0/4

C        10.16.159.24/30 is directly connected, Vlan401

L        10.16.159.25/32 is directly connected, Vlan401

C        10.16.159.56/30 is directly connected, Vlan405

L        10.16.159.57/32 is directly connected, Vlan405

C        10.16.159.152/29 is directly connected, Vlan410

L        10.16.159.153/32 is directly connected, Vlan410

C        10.16.160.0/24 is directly connected, Vlan3160

L        10.16.160.251/32 is directly connected, Vlan3160

ip prefix-list denysubnets: 9 entries

   seq 10 deny 10.16.18.0/24

   seq 20 deny 10.16.128.0/19

   seq 30 deny 10.16.159.4/30

   seq 40 deny 10.16.159.24/30

   seq 50 deny 10.16.159.56/30

   seq 60 deny 10.16.160.0/24

   seq 70 deny 10.18.0.0/16

   seq 80 deny 10.16.162.0/24

   seq 90 permit 0.0.0.0/0 le 32

[Pawan Raut]

Config Looks fine to me could you paste output of below two commands.

sh ip bgp nei 10.16.159.154 advertised

sh ip bgp

[steve martin]

Hello Pawan,

We are using vrfs and there are a lot of old routes that aren't needed.  Let me know if you need more information.  Outputs are on the file.

Thanks

[Pawan Raut · Accepted solution]

As per the output you have provided by you for below commands. I can see the below connected routes are getting advertised from new MPLS. But as you are currently advertising the same routes from older mpls and  beacise of more uptime remote end select the old mpls path as best route. but when you will disconnected old mpls  the same route adversting by new mpls will be consider as best route at remote end. So this is perfectly fine and it will work without issue. Kindly rate for helpful post.

sh ip bgp vpnv4 vrf INSIDE neighbors 10.16.159.154 advertised-routes

*> 10.16.18.0/24 0.0.0.0 0 32768 ?
*> 10.16.128.0/23 0.0.0.0 0 32768 ?
*> 10.16.130.0/23 0.0.0.0 0 32768 ?
*> 10.16.132.0/24 0.0.0.0 0 32768 ?
*> 10.16.133.0/24 0.0.0.0 0 32768 ?
*> 10.16.134.0/24 0.0.0.0 0 32768 ?
*> 10.16.144.0/23 0.0.0.0 0 32768 ?
*> 10.16.159.4/30 0.0.0.0 0 32768 ?
*> 10.16.159.12/30 0.0.0.0 0 32768 ?
*> 10.16.159.24/30 0.0.0.0 0 32768 ?
*> 10.16.159.56/30 0.0.0.0 0 32768 ?
*> 10.16.159.152/29 0.0.0.0 0 32768 ?
*> 10.16.160.0/24 0.0.0.0 0 32768 ?
*> 10.18.0.0/16 0.0.0.0 0 32768 ?

[steve martin]

Thanks Pawan for making it clear, you have given me confidence that it will go well