Routing
Routing

BGP Dual-Home with default route only

‎12-10-2018 01:19 PM

Hello,

 

I've been scratching my head for a week as to what is the best solution to my problem.  I haven't found any other discussion on this topic which I think is pretty common:

 

We have 2 BGP sessions with our upstreams, each announcing a default-route.  If one of the ISP performs an upgrade on their router, BGP goes down and life is good.  However, as their router reloads, the BGP session with us - announcing a default-route - is coming back up before their router as the full table loaded, resulting in a ~30 seconds outage after the BGP neighbor is back up.

 

** I depicted the situation as most people would see it, in our case we have an advantage, we are also the upstream provider.

 

Here are my thought:

 

1.  Have the upstream (still us in our case) receive the default-route from the internet and propagate it to the customer, in this case the default route wouldn't be generated by the PE, avoiding the blackhole situation on reload

 

2.  Use a recursive default route with a next-hop of a summary (eg 192.0.2.0/24) from the upstream (e.g. static route 0.0.0.0/0 next-hop 192.0.2.0)

 

I don't like the first one as it means introducing a default-route in our public ASN.

I don't like the second one as it still a static route in a fully dynamic environment

 

What are your thoughts on this?

 

1 REPLY 1
Routing
Solution
Accepted by topic author flq06
‎12-11-2018 09:00 AM

Re: BGP Dual-Home with default route only

‎12-10-2018 07:21 PM

Hello,

There is always a 3rd option :-)

If Your ISP router is from Juniper, then ask Your ISP team to introduce a delay in announcing the 0/0 to You until this ISP router fully converges

https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/delay-rou...

HTH

Thx

Alex

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