In message <[email protected]>, Masataka Ohta writes: > Tony Finch wrote: > > > BIND 9.10 changes the first state to do variable-size probing: it > > will try 512, 1232, 1432, and 4096, starting at the bottom and > > working up and down depending on what works. The middle numbers come > > from the minimum IPv6 MTU minus space for headers, and the ethernet > > MTU minus v4 and v6 headers to allow for tunneling. > > Your assumption is that there is no extension headers exist. > > But, the problem of current IPv6 specification allows for very > long extension headers (more than 60KB is allowed), some of > which are automatically inserted not under transport/application > layer control.
So? Fragmented packets *do* get through the network. Where they don't it slows up DNS resolution and the firewall usually gets fixed to allow fragments. The break points above only come into play when there are firewalls that block fragmented traffic. One can always add more break points in the future. As for 60K headers, I'll worry about them when they start happening. > So, as Fernando Gont wrote: > > > While this issue/question may be currently masqueraded by the fact > > that we still have IPv4, I wonder what's "the plan" for the IPv6 case > > (at some point, we'll have to rely on whatever such plan is). > > The first thing to do is to obsolete extension headers and > related gotcha in IPv6 specification. > > Even a fragmentation header has annoying requirement. > Masataka Ohta -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [email protected] _______________________________________________ DNSOP mailing list [email protected] https://www.ietf.org/mailman/listinfo/dnsop
