Re: Requirements for IP Multihoming Architectures

[Joe Abley <jabley-ietf@automagic.org>]

On Wed, Mar 21, 2001 at 12:46:34AM +0900, Jun-ichiro itojun Hagino wrote:
> >3.1 Redundancy
> >
> >   By obtaining transit through more than one provider, a network can
> >   insulate itself from certain failure modes of one or more providers,
> >   as well as failures within layer 1 and layer 2 infrastructure.
> 
> 	it looks to me that we should cover "multiple connectivity to
> 	a single provider", like to different NOCs/routers.

Multi-attaching to the same provider is a simplified case of the
general cidr multi-homing technique, which doesn't suffer from:

 + contribution to AS exhaustion (private-use ASNs can be used)

 + path or prefix bloat (the prefixes announced by the multi-homing
   site can be aggregated by the single provider)

However, it also doesn't fully satisfy the stated requirements, which
included the requirement to protect against routing anomolies in a
single autonomous system; the exact text describing the failure mode
is:

   o  Service provider failure, such as a backbone-wide IGP failure, and

It might be worthwhile spelling this out in the draft, I guess.


Joe