IBGP switch vlan traffic

[Artem Volkov]

 Hi friends. Need your help.

 I have a lot of branches, whitch connects to HQ via IBGP. All traffic goes throught main link. I need to change this traffic flow:

 1) In normal (two links work). All vlans work throught main link, but vlan 300 work throught backup link.

 2) When main link goes down, all vlans must flow throught backup link and traffic of vlan 300 must be dropped (don't go to HQ).

                Can i do this only using IBGP without tracking?

Sry for my English.

Regards.

Artem.             

 

[Akash Agrawal]

Hi,

Just with BGP it is not possible and through BGP (or any routing protocol) we can do destination based routing but your requirement is different routing based on source. For sourcebased routing we have PBR (policy based routing).

http://www.cisco.com/c/en/us/td/docs/ios/12_2/qos/configuration/guide/fqos_c/qcfpbr.html

Regards,

Akash

[Joseph Nelson · Accepted solution]

Edit: Not fully-baked solution yet. I will re-post later.

To be brief however, there are ways to do it in iBGP but they are configuration intensive and won't scale especially if you have lots of branch sites. The best solution would be to implement your policy at the branch:

1. Setup IP SLA probe + track to ping ASR1 interface
2. Setup a static route for whatever VLAN300 hosts are talking to in your HQ. This router should have next-hop ASR2; track the object created in Step 1 (i.e. ip route x.x.x.x <mask> ASR2 track x)
3. Setup a policy-route, apply to VLAN300 interface. Set your policy route to "set ip default interface null0"

In this way, if path through ASR1 fails, the rest of the traffic fails over to backup link via iBGP connection. When the IP SLA fails, the more specific static route in Step 2 get's removed. With no explicit route, the policy-route send traffic from VLAN300 to null0.

I can provide some config example if you like.

Rate if helpful...

[Joseph Nelson]

Artem,

Did you find that information useful at all?

[Artem Volkov]

   Thanks , Joseph. And what about vlan 300 traffic, whitch will back from ASR in your solution? Whitch path it selects? 

   I am affraid that it will go throught backup link, but will back throught main link.

[Joseph Nelson]

I'm sorry Artem, can your restate your question?

The failover should work in the way I specified. The trick is that in the policy-route, you say "if I don't have an explicit route ( default route doesn't count) in my routing table, I will null-route this destination." 

This is the theory at least. I can provide a config example but I don't have the equipment  to test with.