Document: draft-ietf-softwire-hs-framework-l2tpv2-10 Reviewer: David L. Black Review Date: December 10, 2008 IETF LC End Date: December 15, 2008 Summary: This draft is on the right track, but has open issues, described in the review. Comments: The draft is well-written, with a lot of details that will be valuable to implementers. I have two open issues: (1) Section 5.1 of this draft is clearly defining a softwire profile of L2TPv2 in that it states extensive requirements on AVP usage (and AVP contents in some cases) for softwires. Use of this profile is not explicitly signaled - the expectation is that both the SI and SC will be implemented in accordance with this draft, and won't try to communicate with L2TPv2 implementations that aren't using this profile. As the requirements of this softwire profile appear to differ from RFC 2661, defining an AVP to signal use of this profile seems like a good idea (its use should be required). (2) This is more of a minor annoyance than an open issue, but it does need attention. This draft uses UDP as part of an IP-in-IP tunnel, so the UDP guidelines in RFC 5405 apply. Note that Section 3.1.3 of RFC 5405 indicates that no additional congestion control is required for this scenario beyond what is already done for the IP traffic carried through the tunnel. That should be noted in this draft, and RFC 5405 should be scanned for any other considerations that may apply to this draft. Everything else I found is relatively minor: - Please add CPE and LNS to the abbreviations section. - Most of the text after the figure in each of Sections 3.1.1 through 3.1.4 is common. Consider factoring it out into one location. Ditto for 3.2.1 to 3.2.4. It's fine to not do this if the result would be difficult to follow. - In Section 5.1.1.3, please clarify that the "SHOULD NOT send" requirement applies only to AVPs not covered in sections 5.1.1, 5.1.1.1 and 5.1.1.2 . - I found a number of lower case instances of "must", "should" and "may" that are candidates for upper case (i.e., RFC 2119 usage). Please check all of these and upper case as appropriate. - Please expand the ULA acronym on its first use in Section 6.1.1 .