> The implementation is different from what is mandated by -06, for a few > reasons. As usual, I'd like people to comment whether I'm being silly or > whether some of the MUSTs in the draft can become SHOULDs or even MAYs. > Note that I haven't checked RFC 7084 yet [2]. Didn't we have a thread on 7.2 a few days ago, already? At least I feel like having a slight deja-vu replying. Anyway.
Please read into 7084, Section 7.2 will hopefully go away entirely. We already refer to 7084 and that section just duplicates some parts of it thus it is mainly redundant. In the end I think v6ops is the more appropriate address for most of these discussions anyway. I will reply with what the change would be, if we default back to 7084 behavior. > > - Since I don't implement DHCPv6, I'm not setting the "O" flag; for some > reason, Section 7.2 says that this flag MUST be set. O flag will be up to the implementor, if the router supports stateful dhcpv6 both M and O flags are SHOULD. Personal note: AFAIK statelss DHCPv6 is the only way for Windows to receive DNS servers for IPv6. > - I always set a non-zero default router lifetime, which is clearly > wrong. Section 7.2 says that this flag MUST be set when a default > route is "known in the HNCP network". This requirement, or at least > its formulation, has multiple issues to my eyes: > > (1) Does that mean a default route advertised in the Homenet routing > protocol, or do non-Homenet default routes count? All do, imagine you are the only (edge) router and your default route comes from your ISP via RAs. > (2) How do you define a default route in the presence of source- > specific routing? Maybe this should be discussed in v6ops? > (3) This requires either monitoring the kernel's routing tables or > snooping the routing protocol, and this is the only place in HNCP > that imposes such a requirement; it is a pity to add that sort of > incestuous interaction between protocols just for this single > feature. Snooping the IGP is not an option. You may not even run an IGP, e.g. if you are an isolated node with only ISP and client connectivity. > (4) A routing protocol can have hiccups at a faster rate than what > RFC 4861 is designed to handle. For example, babeld in its > default configuration will react to a newly discovered wired link > within 2s, and to a lost link within 6s. You don't want to flap > your RAs every 4s on average. > > I think a better solution is needed. I'm planning to declare myself > a default router whenever I know of an IPv6 delegated prefix that's > not a ULA, and hope for redirects to fix any resulting issues. As noted, the requirement came from 7084. > - I'm setting the A flag even for prefix lengths different from /64, > which is a reasonable thing to do according to my reading of RFC 7421. > HNCP says that it should be done "whenever the prefix is suitable for > stateless configuration", whatever that means. 7084 says A and L MUST be set by default, though I think that RFC only deals with /64 assignments in its pure version. > > - Section 7.2 says that the RDNSS option must have "appropriate > contents". What's appropriate? Should I merge all of the DHCP6-DATA > TLVs that I've seen, should I merge just the ones from external > connections that have delegated prefixes that I'm using for IPv6 > assignments, or should I pick just one DHCPv6-DATA section? I'm > currently merging everything, not even checking for duplicates. > > - I'm not sending a DNS Search List, although the spec tells me I SHOULD, > since (1) I hate DNS search lists (shortcuts should be done in the > application, not in the resolver), and (2) the spec doesn't tell me how > to build a suitable DNS search list. 7084 says the router MUST support providing the option, nothing about the contents. Btw. HNCP mentions search domains in 8.1 but this is only a special case. > > - I'm not doing the router preference (RFC 4191) dance, since I don't > understand how it interacts with multihomed hosts. (For single-homed > hosts it's irrelevant, since redirects will make things right.) > I also generally prefer the hosts, not the routers, to be smart (think > MP-TCP, think MP-Mosh, think MP-Kademlia [3]). Yes, with the default to 7084 this would be gone anyway. _______________________________________________ homenet mailing list [email protected] https://www.ietf.org/mailman/listinfo/homenet
