RE: EIGRP vs EBGP for fast failover

Paul,

What kind of failover are you looking to reroute around within 5 seconds? Always include the details that you are looking for so you can get a "more" exact answer.

Before really worrrying about this, think of what business reasons are needed for 5 second failover?

Most customers are looking for failover of their WAN circuit (to the Internet in this case) to the backup Circuit.

If this is all you are looking for, then here's what I suggest. I'm also assuming that you are only getting a 0.0.0.0 route inbound from the SP.

If the WAN link is a P2P serial (T1), then ensure BGP fast fallover to detect if a physical interface goes down. If you have a metro-e, see if the provider will agree to negoitate a lesser hold down / hello time in the bgp timers. But these are really just for edge failures but most customers really only see and want this.

Many SP will not let you make the timers too low (1 and 3 for example) but you can just try it within BGP and reset the session and see (show ip bgp neighbor, etc) if the negoitaited values took hold. If the SP has a hard minimum, then the session won't come up, or will negotate to a higher value depending on your configs.

As was mentioned before, fast convergence and BGP don't match. Most folks will aggregate their links (multilink, etc) and diversify their traffic (load balance so that if a major outge does occur, it only impacts a segment while convergence happens. Also, peering to loopbacks can provide reduncancy but many SP won't allow for that type of setup. Another items is route dampening...ensure that your SP is not dampening routes before wanting to really speed up BGP fail over.

I hope this helps,

Andre

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Sorin Platon
Sent: Tuesday, March 09, 2010 6:50 PM
To: Paul Bernard
Cc: Ronnie Angello; ccielab_at_groupstudy.com
Subject: Re: EIGRP vs EBGP for fast failover

Look for BGP backdoor or OER might be the silver bullet

On Tue, Mar 9, 2010 at 6:07 PM, Paul Bernard <theballman2_at_gmail.com> wrote:

> Let me give more information. I need to failover to a backup internet
> connection from an MPLS connection in under 5 seconds. I can do this with
> modifying the EIGRP timers, but I want to know if I can do this with EBGP
> as
> this is what a potential MPLS provider supports (they do not support
> EIGRP).
>
> -----Original Message-----
> From: Ronnie Angello [mailto:ronnie.angello_at_gmail.com]
> Sent: Tuesday, March 09, 2010 2:54 PM
> To: Paul Bernard
> Cc: ccielab_at_groupstudy.com
> Subject: Re: EIGRP vs EBGP for fast failover
>
> You probably need to provide more information. How is this working
> today with EIGRP? How would running BGP benefit you in this
> particular case? Are you BGP peering with each provider and using
> EIGRP as an "IGP lifeline?" What do you consider fast failover?
> Typically you don't mention BGP and fast convergence in the same
> sentence... :) What else are you trying to accomplish?
>
> On Tue, Mar 9, 2010 at 5:24 PM, Paul Bernard <theballman2_at_gmail.com>
> wrote:
> > I want to use EBGP to do a fast failover from one provider to another.
> Right
> > now, I have it working with EIGRP. Is there anyway of doing this with
> EBGP?
> > What are the consequences of doing this?
> >
> >
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> Ronald Angello
> Network Architect
> CCIE 17846
> CCDP, CCIP, CCNP
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Received on Tue Mar 09 2010 - 19:19:44 ART