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@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Philip Matthews Sent: Friday, April 15, 2005 3:40 PM To: nanog@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