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