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

  • From: Lamar Owen
  • Date: Sat Jun 02 10:36:45 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
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