Hi Peng, Satoru, Thanks for your comments and suggestions. Actually, I think there are two kinds of routing issues around here, and we should take appropriate planning for our stateless 4v6 routing system.
The first one is what Peng has mentioned above, that de-aggregated IPv4 IGP addresses blocks together with embedded non-continuous port set would have impact on IPv6 routing system. This situation has no relationship with shared-mode or exclusive-mode, and I personally think we can reduce this impact with careful IPv4 address planning. Here are two possible ways: -- Guarantee that one shared-IPv4 address would only be allocated within the same BNG (say, BRAS, etc). Thus, non-continous port info will no longer be needed to shown up in IPv6 IGP and all the packets with the same shared-IPv4 address will be destined to the same BNG. -- Select the same IPv6 stateless prefix with native IPv6 prefix in a certain area. For example, if 2001:c68:1122::/48 is the prefix for one MAN, we can also use it for stateless IPv6 prefix , followed by shared IPv4 address/port set. In this way, de-aggregated IPv6 routings can be further aggregated in the upper level (say, backbone network). However, in this way, this IPv6 prefix is relatively long and it would be difficult to ensure the whole stateless IPv6 prefix (including IPv4 address/port set) to be less than /64 (easier for SLLAC). The second one is to deal with the co-existence scenario for shared-mode and exclusive-mode (or other differentiated situation). As suggested by Satoru and Remi, it can either be accomplished by IPv4 routing in stateless GW, or by mapping rule specification. Anyway, it still have to do some kind of lookup, no matter whether it is a routing table or other kinds of database. But I also agree that the performance would not be a big problem to handle these additional prefix-based rules. Best wishes Qiong Sun 2011/7/29 Peng Wu <[email protected]> > Hi Satoru, > > >> However, if we introduce multiple domains with multiple IPv4 prefix > pools ( the number of each domain is N1, N2, N3,... Nm) , then the entry > number of IPv4 routing table will be N1+N2+N3+..+Nm. In current situation, > Nm would not be a small number anymore. So maybe some more optimization work > will still be needed to make it more "stateless" ? > > > >What do you mean 'the entry number of IPv4 routing table'? > >Do you presume that your IGP routing has almost 300K routes as same number > of current internet full routes? > > If I get Qiong correctly, she means that, suppose the IPv4 IGP addresses > blocks are quite de-aggregated already. If the ISP upgrade the network to > IPv6, and support IPv4 using stateless 4v6 with the same IPv4 address > distribution, then the IPv4 IGP kind of introduce the IPv4 IGP routing table > into IPv6. > > If this situation does exists, then it's an interesting operation problem. > >
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