[isp-bgp] Re: isp-bgp digest: September 24, 2004

[James <haesu@...>]

On Tue, Sep 28, 2004 at 05:47:21PM -0400, Dean Anderson wrote:
> > Subject: Load Balance.
> > From: Serge Paquin <isp-bgp@...p.ca>
> > Date: Fri, 24 Sep 2004 18:34:56 -0400
> > X-Message-Number: 1
> > 
> > Hello,
> > 
> > 	I am trying to find the best way to load balance 2 links that I have.
> > 
> > 	I have 2 T1's from different providers.  The providers are quite 
> > similar in there coverage but my balance in most cases at best is 66/33.
> > 
> > 	Most of my traffic is outbound and I'm wondering if CEF can help me out.
> > 
> > 	I have 2 routers running HSRP for the default route in my inside network.
> > 
> > 	One T1 is terminated on a Cisco 2621 that uses BGP4 to advertise is 
> > netblock but runs a default route.
> >
> > 	The other T1 is terminated ona 2691 that has a full BGP session to the 
> > provider and also a full BGP Multihop session to my other provider via 
> > the 2621.
> > 
> > 	FE0/0 on both routers are on the inside network that is running HSRP.
> > 
> > 	FE0/1 is a P2P link between the two routers.
> > 
> > 	
> > 	Since the providers are very similar I wonder if I can filter all but 
> > the default route on the 2691 which would leave me with 2 default routes 
> > and use CEF on a per destination basis to balance the outbound traffic.
> 
> I doubt that CEF does anything on a 2621, but turning it on couldn't hurt.  

It does help in some of my deployments at client sites. But then again, by the time
your 2600 gets exhausted like that, a new router upgrade should be in order... :)

> It won't help with load balancing, however.
> 

It does if you have equal cost metric routes. 
'ip load-sharing_(per-packet|per-destination)' requires a FIB, aka cef enabled.
If however using MLPPP, cef is irrelevant.. although I find MLPPP to tax quite a
chunk of cpu on the router..

But really... trying to combine bandwidth and gain "load balancing of bits or
increase throughput" with BGP is like trying to nail something with something
other than a hammer.

-J

> > 	I'm not sure if this will work or if there is a better solution for me. 
> > Trying to play with BGP parameters are giving me luke warm results at best.
> 
> What address space do you have?  Do you have an ASN or have both providers 
> given you a private ASN?
> 
> -- 
> Av8 Internet   Prepared to pay a premium for better service?
> www.av8.net         faster, more reliable, better service
> 617 344 9000   

-- 
James Jun                                            TowardEX Technologies, Inc.
Technical Lead                        Network Design, Consulting, IT Outsourcing
james@...                  Boston-based Colocation & Bandwidth Services
cell: 1(978)-394-2867           web: http://www.towardex.com , noc: www.twdx.net

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