NAT Multihoming (was:Re: NANOG 40 agenda posted)

Sat Jun 2 14:31:05 UTC 2007

On Friday 01 June 2007, Vince Fuller wrote:
> If you think about it, the NAT approach actually offers the possibility of
> improved routing scalability: site multihomed with NATs connected to each
> of its providers could use topologically-significant (read "PA") global
> addresses on the NATs while using the same private address space on their
> network. 

Cisco has a whitepaper entitled "Enabling Enterprise Multihoming with Cisco 
IOS NAT" that addresses this.  See 
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a0080091c8a.shtml
as well as RFC2260.

There are indeed a few thorny issues with this approach; the largest issue is 
that all connectivity becomes DNS-dependent and raw IP addresses (from both 
the inside and outside) become virtually useless.  Running servers behind 
this scheme, while doable, is difficult.
-- 
Lamar Owen
Chief Information Officer
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu