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BGP 2nd Default GW to ISP

I've attached a diagram. I'm wanting to advertise another default gateway to our ISP via BGP. I want to be able to ensure that this default route also gets put in their table so as to load balance between the 2 sites. Am I going to have to get in touch with the ISP for this?

BGP1 currently is the default gateway for all locations. BGP 2 is a backup site (our DR) that I want to use as another path to the internet via the MAN connection. The Red connection from BGP 3 is the 2nd path that I'd like it to take. I've got a lab set up, but even after changing maximum-paths to 2, it doesn't put the second default route in the routing table.


HTH, John *** Please rate all useful posts ***
New Member

Re: BGP 2nd Default GW to ISP

The configuration of your routers would be welcome.

But if  you are in the same AS, for all the 3 routers, your problem is the fact of the bgp split horizon rule.

BGP-1 advertise certainly via "default-information originate" to BGP-2 and BGP-3 but BGP-2 or BGP-3 doesn't advertise this default route which has been passed by an iBGP peer.

An iBGP peer cannot advertise an iBGP learned route, it's a loop prevention mechanism.

You can build subconfed to override this behavior and make it happen as you want.



BGP 2nd Default GW to ISP

It's a basic setup at this point. Both my CE routers are advertising into the provider. The provider gets it, but only puts one route in the table:

*               0             0 65127 i

*>                     0             0 65100 i

Currently, my lab doesn't have mpls set up. I can do this if I were expecting a different outcome.

Here's the ISP router:

router bgp 1

no synchronization

bgp log-neighbor-changes

network mask

network mask

network mask

neighbor remote-as 65100

neighbor default-originate

neighbor remote-as 65127

neighbor remote-as 65003

maximum-paths 3

no auto-summary


HTH, John *** Please rate all useful posts ***

BGP 2nd Default GW to ISP


AFAIK, even when maximum-paths command used, both prefixes have to come from the same neighboring AS to be used for BGP load balacing.




New Member

BGP 2nd Default GW to ISP

Always better with a show command to understand.

Milan find the issue, Thotsaphon on the other post share a wonderfull command to circumvent the issue:

bgp bestpath as-path multipath-relax


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