Le 21 juil. 2011 à 19:27, Wojciech Dec a écrit : ... >> . Packet X is submitted to ordinary IPv6 routing because its payload IS NOT >> an IPv4 packet. >> . Packet Y has its contents directly submitted to the CE NAT44 because its >> payload IS an IPv4 packet. (The 4V6 address 2001:db8:a::1, never treated as >> a destination on any IPv6 link, is in fact a "dummy address".) >> =============== > > Please describe what you mean by an IPv6 "dummy address", or where can > one find it described?
OK, ignore the "dummy address" bit. (The behavior is AFAIK clear, with no need for a new name.) Let's now be constructive, with solutions. > Oh, one other thing: Say that IPv6 Host H was actually running an > IPinIP tunnel/application and wants to receive such traffic. How does > the model you describe work then? OK, that's a good point: if hosts behind a 4V6 CE are permitted to have any addresses that start with the CE assigned IPv6 prefix, a host whose address is the same as the specified 4V6 address won't be able to do IPv4 in IPv6 tunneling per RFC 2473. SOLUTION: This is easily avoided if the 4V6E encapsulation is done with a Protocol number different from 41. Since Protocol 41 is in IANA for point-to-point tunnels of RFC 2473, it makes sense to have a new one for stateless multipoint tunnels. > ... in the S46 set-up with the > characteristics as outlined in my initial reply, without system > elements having duplicate IPv6 addresses, the problem you mention does > not appear in neither translation nor tunneling modes. OK, but the setup of your initial reply is only for CE's being assigned a /64, which imposes a single LAN-side link. Shorter IPv6 prefixes assigned to multiple-link sites lead to more complex analysis. SOLUTION: If the IID of 4V6 addresses is one that never needs to be assigned to work in IPv6, which isn't difficult to ensure, no conflict is possible between a hosts IPv6 address and a 4V6 address. A possible IID value is that of an embedded IPv4 address (as in ISATAP), with a reserved IPv4 address that no network would use. If this address is 0.0.0.0, the 4V6 IID is 0:5efe:0:0. (If a completely new address is preferred,it could for instance be 192.0.0.0, to be registered by IANA to mean "unspecified IPv4 address", the equivalent of :: in IPv6. Both solutions are AFAIK extremely simple, and do solve the two issues. I hope they will be looked at constructively. Regards, RD _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
