BGP default route from two provider

Unanswered Question
Jul 3rd, 2009
User Badges:

Dear all,


I am having two Internet link from two provider and i am taking default route from both the provider


One provider is having cisco router so default in my router showing origin as "incomplete"


while other provider is having juniper router and origin is showing "IGP" in my router


Is there anything by which I at my end change this behaviour and change the path selection criteria so that

forward traffic to internet goes via. both the link.


Thanks & Regards

mahesh

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
dan_track Fri, 07/03/2009 - 02:41
User Badges:

Look into route-maps. You can define settings in there.

Istvan_Rabai Fri, 07/03/2009 - 02:56
User Badges:
  • Gold, 750 points or more

Hi Mahesh,


Before evaluating the origin code of a prefix, the BGP path selection process evaluates weight as the first step (in Cisco routers only).


So one solution could be the following:

You can set the weight of the default route on the Cisco router inbound using the "neighbor x.x.x.x weight" command, where x.x.x.x is the BGP router on the ISP side.


This will result in that the Cisco router will route traffic hitting it to its own default route.


The Juniper router also will route traffic hitting it to its own default route (weight is not considered in Juniper routers).


Edit: My supposition here is that both routers learn each other's default route through an iBGP connection.


You will need to configure your IGPs inside your AS to route traffic to the Cisco or Juniper router to do some load sharing between the two edge routers and ISP links respectively.


I also recommend you to test the failover scenarios.


Cheers:

Istvan

mahesh-gohil Fri, 07/03/2009 - 03:12
User Badges:

I think my problem is not understood


i am having single cisco router which is connected to other cisco router (One provider) and other Juniper router (next provider).


they both announces a default route to me. My requirement is to send traffic via. both the link. Now after doing multipath I can see both the route in BGP table but only one become best from provider who is having juniper router (due to origin as "IGP")


Now if I set weight to one of route only that route will became best and forward traffic goes to one link only.


I need such a thing where both default became best in my routing table


hope this understood


Regards


mahesh-gohil Fri, 07/03/2009 - 05:10
User Badges:

Now I change the origin and now I am getting both the links routes with equal parameter .


but yet traffic is not going via both the link


HO-ILL-RTR#sh ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 2

Paths: (2 available, best #2, table Default-IP-Routing-Table)

Multipath: eBGP

Flag: 0x820

Not advertised to any peer

1234

125.21.249.113 from 125.21.249.113 (203.101.87.90)

Origin incomplete, metric 100, localpref 100, valid, external

5678

115.113.121.25 from 115.113.121.25 (192.168.196.6)

Origin incomplete, metric 100, localpref 100, valid, external, best

Istvan_Rabai Sat, 07/04/2009 - 04:46
User Badges:
  • Gold, 750 points or more

Hi Mahesh,


I got your point now.


I tested this scenario on routers but it seems to me that BGP does not support multipath for default routes.


However, I did not find any references in Cisco documentation about this.


Cheers:

Istvan

Actions

This Discussion