Preferred BGP Route into Network over Backup Link

Unanswered Question
Oct 19th, 2007
User Badges:

We have a pretty simple layout with two ISPs. Our preferred path into the network is through one carrier, but the traffic comes into through the carrier we would prefer as a backup. I've prepended the ASN multiple times, but this hasn't fixed the problem. Any suggestions?


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
gaurav_thapar79 Fri, 10/19/2007 - 10:51
User Badges:


Can you share how have you advertised your prefixes and how have you applied PBR to control the downstream traffic?

please share.

baskervi Fri, 10/19/2007 - 11:13
User Badges:

The problem is better identified. A local ISP said he is seeing the ASN prepended from Levl3 (one peering partner), but he isn't getting a route from AT&T who they also peer with. We are in the process of contacting AT&T.

Thanks for your time.

saimbt Wed, 11/14/2007 - 23:42
User Badges:


I have a very strong feeling that ISP1 and ISP2 have a peering agreement.

A thought to it would be.

As the ISP2 to lower the local preference within his AS for your network range to either the default so that AS prepend helps or less than the local preference he has set for ISP1.



This Discussion