Control send default route with BGP

[sebastien3]

Hello,

I have two ASBR routers:

- R1 eBGP session with HE full-view IPV4/IPV6

- R2 eBGP session with Cogent full-view IPV4/IPV6

The two ASBRs are full-meshed and sh ip bgp 0.0.0.0 indicates two next-hops on R1 and R2.

Both ASBRs have an iBGP session with multiple ABRs.

The BGP configuration of the ASBRs include network 0.0.0.0 and network::/0 to send only the default route to other ABRs.

If for example the BGP session between R1 and HE drops, R1 will still send 0.0.0.0 to the other ABRs... !!!!

How to stop sending the default route 0.0.0.0 and ::/0 to the ABRs if there is a problem with the eBGP HE/COGENT session?

Thank you

[Flavio Miranda]

Do you control HE/COGENT ?

If so, you can make HE/COGENT advertise the default route ASBRs  and on the ASBRs  you do "default-information originate" command.  This way, if the default route stop coming from HE, it will not be advertise by ASBR.

[sebastien3]

@Flavio Miranda 

What do you mean by "controlling HE/COGENT" ?

[Flavio Miranda]

I mean, this is a Lab and you can change anything or prodution environment and  you need to ask ISPs:?   One way or another you can receive the default routing instead using the network command.

[Jon Marshall]

You could ask both ISPs to send default route as well and then just filter that to your IBGP routers. 

Alternatively you may be able to use conditional route advertisement although never done with IBGP peers so can't say for sure it would work. 

Jon

[sebastien3]

I have a third ASBR which is connected to an IX. I need to have the full-view from ISPs, the default route is not usable...

I am in production not in a LAB.

[Jon Marshall]

I wasn't suggesting only accepting the default route from your ISPs, I was suggesting asking them to send that as well as the full routing table. 

That way you can pass it on to your IBGP routers and if the link goes down you will no longer be sending it. 

Jon