there's also the rsip extension for e2e ipsec from the nat wg: http://www.ietf.org/internet-drafts/draft-ietf-nat-rsip-ipsec-00.txt other rsip drafts: http://www.ietf.org/internet-drafts/draft-ietf-nat-rsip-framework-01.txt http://www.ietf.org/internet-drafts/draft-ietf-nat-rsip-protocol-01.txt -gabriel