North American Network Operators Group
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Re: Enterprise Multihoming

  • From: Gregory Taylor
  • Date: Thu Mar 11 11:41:56 2004

Mutli-homing a non-ISP network or system on multiple carriers is a good way to maintain independent links to the internet by means of different peering, uplinks, over-all routing and reliability. My network on NAIS is currently multi-homed through AT&T. I use a single provider as both of my redundant links via 100% Fiber network. Even though this is cheaper for me, all it takes is for AT&T to have some major outage and I will be screwed. If I have a backup fiber line from say, Global Crossing, then it doesn't matter if AT&T takes a nose dive, I still have my redundancy there.

That is why most non-ISPs hold multihoming via different providers as their #1 choice.

Greg

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?

Flame on. :-)

Thanks,
John
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