RE: [nsp] 2 ISPs, BGP and load-balancing

From: Stephane Perez (
Date: Thu Dec 27 2001 - 11:22:49 EST

 regarding your BGP configuration, you can do the following:
for the incoming traffic (dowload from the internet):
   Use the default behaviour about the AS path length except if one of your
ISP is giving you more addresses than the other (and depending of the costs)
for the outgoing traffic:
   You can specify the MED value which will helps you to influence the way
the traffic from the internet is using for reaching your network.


PEREZ Stephane
Carrier IP Specialist, Shasta GTS
Nortel Networks
ATS IP Core Infrastructure
25, allee Pierre Ziller
06560 Valbonne, FRANCE
Phone: +33 4 92 96 18 05 Mail :
Fax : +33 4 92 96 16 68 www :
Esn : 296-1805 Intranet : <>
ICQ : 120356046

-----Original Message-----
From: Rick Casarez []
Sent: Thursday, December 27, 2001 1:51 PM
Subject: Re: [nsp] 2 ISPs, BGP and load-balancing


    What kind of load balance are you looking for and which direction?
Inbound or outbound or both?

      If you want really load balancing you can, if your router can handle
it, run 'maximum-paths 2' global BGP command on your router. This will allow
your router to choose 2 best paths instead of the 1 (the default). If you
are receiving only partial routes from each provider then you could run
equal weight default routes pointing towards each and what doesnt get
captured from the provider announcements will be sort of balanced out for
I would recommend the latter personally.

        For inbound load-balancing it is a little bit harder and would
involve tweaking attributes for subnets of your prefix (or multiple
prefixes) to the providers. That I would recommend doing until it works like
you want it to.


>From: TMS
>Subject: [nsp] 2 ISPs, BGP and load-balancing
>Date: Wed, 26 Dec 2001 06:52:08 -0500
>I have two 4mbps internet links connected to 2 diffrent ISPs. How
>I can create load-balancing between both ISPs ? At
>this moment my router configuration (Cisco 7206VXR, NPE-400)
>looks like that:
>router bgp 60000
> network
>neighbor weight 50
>neighbor remote-as 10000
>neighbor description ISP-1 (ex.UUNET)
>neighbor filter-list 1 out
>neighbor route-map SETMETRIC in
> neighbor weight 50
> neighbor remote-as 20000
> neighbor description ISP-2 (ex.AT&T)
> neighbor filter-list 1 out
> neighbor route-map SETMETRIC in
>ip as-path access-list permit ^60000$
>ip as-path access-list deny .*
>route-map SETMETRIC permit 10
>match ip address 1
>set metric 100
>access-list 10 permit any
>Any propositions ? Maybe I must set local-preference or
>as prepend for neighbors ?
>greets, TMS


Send and receive Hotmail on your mobile device: Click
<> Here

This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:12:58 EDT