On Thu, Oct 14, 2021 at 2:07 PM Brian E Carpenter <brian.e.carpen...@gmail.com> wrote: > > On 14-Oct-21 22:41, Ted Hardie wrote: > > On Wed, Oct 13, 2021 at 9:28 PM Brian E Carpenter > > <brian.e.carpen...@gmail.com <mailto:brian.e.carpen...@gmail.com>> wrote: > > > > > > > > Including semantics *of any kind* in an IP address is a very fundamental > > change to the concept of IP.<https://www.ietf.org/mailman/listinfo/ipv6> > > > > > > Would you mind elaborating what you mean by semantics in the statement > > above? Clearly there are semantics in things like the IPv4 multicast and > > experimental address ranges (aka "Class D" and "Class E"); especially for > > the multicast case, the very fundamental semantics of the distribution are > > signalled using the address and there has been significant deployment using > > those semantics. Isn't that semantics in the meaning above? > > Yes, I should have restricted my remark to *unicast* addresses. But there > is a difference, I think, between semantics that describe the *type of > address* and semantics that actively describe *what the recipient is going to > do*. It's the latter that I was getting at. > Brian,
Joel's description is very good, and it makes me think that this mechanism is best described as yet another form of NAT. Similar to a NAT device, these devices are rewriting destination addresses per some algorithm which is not necessarily exposed to the outside world. In both NAT and Sid compression, packets are being routed to some intermediate node which is performing address translation and forwarding. The Sid compression method has the advantage that the translation is stateless. While SId compression is explicit as encoded in the destination address set by the sender, it seems like Sid compression would still be transparent to any intermediate node that's not the destination address-- that would include the Internet in packets that were leaked. Given that NAT seems to work okay, I don't immediately see how SId compression would be any more of a problem :-) Tom > (This applies to Carsten's comment too. Port numbers or multiple addresses > per host are not actively describing what the recipient will do; they're just > numbers.) > > Also, I tried not to express shock and horror at the notion of semantics in > address, but concern about how this will impact existing hardware and > software. > > > > > Thanks for any clarification, > > > > Ted > > > > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > i...@ietf.org > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- _______________________________________________ spring mailing list spring@ietf.org https://www.ietf.org/mailman/listinfo/spring
