[68400] in North American Network Operators' Group
Re: Enterprise Multihoming
daemon@ATHENA.MIT.EDU (Jay Ford)
Thu Mar 11 11:18:09 2004
Date: Thu, 11 Mar 2004 10:15:00 -0600 (CST)
From: Jay Ford <jay-ford@uiowa.edu>
Reply-To: Jay Ford <jay-ford@uiowa.edu>
To: John Neiberger <john.neiberger@efirstbank.com>
Cc: nanog@merit.edu
In-Reply-To: <s0502bd9.071@efirstbank.com>
Errors-To: owner-nanog-outgoing@merit.edu
On Thu, 11 Mar 2004, John Neiberger wrote:
> On another list we've been having multihoming discussions again and I
> wanted to get some fresh opinions from you.
>
> For the past few years it has been fairly common for non-ISPs to
> multihome to different providers for additional redundancy in case a
> single provider has problems. I know this is frowned upon now,
> especially since it helped increase the number of autonomous systems and
> routing table prefixes beyond what was really necessary. It seems to me
> that a large number of companies that did this could just have well
> ordered multiple, geographically separate links to the same provider.
>
> What is the prevailing wisdom now? At what point do you feel that it is
> justified for a non-ISP to multihome to multiple providers? I ask
> because we have three links: two from Sprint and one from Global
> Crossing. I'm considering dropping the GC circuit and adding another
> geographically-diverse connection to Sprint, and then removing BGP from
> our routers.
>
> I see a few upsides to this, but are there any real downsides?
Many/most of my external connectivity problems are provider-related rather
than circuit-related. Having two circuits to a single provider doesn't help
when that provider is broken. I'm not saying that multi-ISP BGP-based
multi-homing is risk-free, but I don't see multi-circuit single-provider as a
viable alternative.
________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford@uiowa.edu, phone: 319-335-5555, fax: 319-335-2951
