Adam Roach has entered the following ballot position for draft-ietf-bfd-vxlan-09: No Objection
When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-bfd-vxlan/ ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- Thanks for the work that everyone has put into this document. I have a couple of relatively important, related comments that should be taken into account prior to publication. --------------------------------------------------------------------------- §3: > As per Section 4, the inner destination IP address SHOULD be set to > one of the loopback addresses (127/8 range for IPv4 and > 0:0:0:0:0:FFFF:7F00:0/104 range for IPv6). Please consider reformatting this IPv6 address according to the recommendations of RFC 5952 (paying particular attention to sections 4.2.1, 4.3, and 5): ::ffff:127.0.0.0/104 It's also worth noting that, as a practical matter, modern operating systems do not seem to bind to anything in the IPv4-mapped range assigned to IPv4 loopback: Linux: ~$ ping6 ::ffff:127.0.0.1 PING ::ffff:127.0.0.1(::ffff:127.0.0.1) 56 data bytes ^C --- ::ffff:127.0.0.1 ping statistics --- 14 packets transmitted, 0 received, 100% packet loss, time 13316ms MacOS: ~$ ping6 ::ffff:127.0.0.1 PING6(56=40+8+8 bytes) ::ffff:127.0.0.1 --> ::ffff:127.0.0.1 ping6: sendmsg: Invalid argument ping6: wrote ::ffff:127.0.0.1 16 chars, ret=-1 It is not clear to me whether this poses an issue for your intended usage. In any case, please do not refer to ::ffff:127.0.0.0/104 as "loopback addresses": IPv6 has only one loopback address defined (::1). The range you cite is best described as "IPv4-mapped IPv4 loopback addresses." Alternately -- and this is probably better -- use "::1/128" instead of "::ffff:127.0.0.0/104" for the inner IP header destination address. As an aside, I share Benjamin's unease around the use of loopback addresses in this fashion. It may be worth noting that IETF protocols can reserve addresses in the 192.0.0.0/24 and 2001::/23 blocks if necessary, and such reserved addresses won't ever correspond to a valid destination. (There is corresponding text in section 4 that all of the preceding pertains to as well) --------------------------------------------------------------------------- §9: > This document recommends using an address from the Internal host > loopback addresses (127/8 range for IPv4 and > 0:0:0:0:0:FFFF:7F00:0/104 range for IPv6) as the destination IP > address in the inner IP header. Using such address prevents the > forwarding of the encapsulated BFD control message by a transient > node in case the VXLAN tunnel is broken as according to [RFC1812]: > > A router SHOULD NOT forward, except over a loopback interface, any > packet that has a destination address on network 127. A router > MAY have a switch that allows the network manager to disable these > checks. If such a switch is provided, it MUST default to > performing the checks. In addition to the comments above about IPv6 address formatting, the improper use of "loopback" terminology as it applies to IPv6, and concerns about using localhost: it's worth noting that this text in RFC 1812 refers to IPv4 routers -- RFC 8504 has no equivalent language, and so the use of ::ffff:127.0.0.0/104 implies no special router handling. ::1 *probably* does, at least as a practical matter.
