On Fri, Sep 07, 2001 at 10:55:49AM -0700, Mike Batchelor wrote:
NAT rewrites certain packet data fields (src addr, src port, sometimes mac addr). So does a ordinary router (ttl decrement). One breaks end2end, the other does not. What is the difference?
NAT rewrite more than that, try reading http://www.cisco.com/warp/public/cc/pd/iosw/ioft/ionetn/prodlit/1195_pp.htm In particular, it rewrites addresses _in the data portion of the packet) for the following protocols: ICMP, FTP, NetBIOS, RealAudio, CuSeeMe, DNS, Netmeeting, H.323, PPTP and several others. That's what makes it violate the end2end principal, your _data_ is changed by NAT. -- Leo Bicknell - bicknell@ufp.org Systems Engineer - Internetworking Engineer - CCIE 3440 Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org