Service providers that NAT their whole network?

Reeves, Rob rreeves at arbinet.com
Fri Apr 15 21:15:01 UTC 2005



Back when I worked at RCN in 1999, they had begun putting cable modem
customers behind NAT using 10/8 addresses.  This occasionally drew
complaints from customers who were expecting a public IP (probably
wanted to host a server), but they weren't given much choice.  Whether
or not they're still NATing, I have no idea.

I can see the benefits for residential services like cable modem or even
dial-up when there will never be a need for multihoming.  Practically
unlimited IP pool, and I assume it's easier to control things like worm
propogation (correct me if I'm wrong).  However, I'm sure there's
several compromises you'd have to make in order to operate this way.

-Rob


-----Original Message-----
From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On Behalf Of
Philip Matthews
Sent: Friday, April 15, 2005 3:40 PM
To: nanog at merit.edu
Subject: Service providers that NAT their whole network?



A number of IETF documents(*) state that there are some service
providers that place a NAT box in front of their entire network, so all
their customers get private addresses rather than public address. It is
often stated that these are primarily cable-based providers.

I am trying to get a handle on how common this practice is.
No one that I have asked seems to know any provider that does this, and
a search of a few FAQs plus about an hour of Googling hasn't turned up
anything definite (but maybe I am using the wrong keywords ...).

Can anyone give me some names of providers that do this?

Can anyone point me at any documents that indicate how common this
practice is?

- Philip

(*) Some IETF documents that mention this practice:
     - RFC 3489
     - draft-ietf-sipping-nat-scenarios-00.txt
       (now expired, but available at
 
http://www.ietf.org/proceedings/02jul/I-D/draft-ietf-sipping-nat-scenari
os-00.txt





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