smd(_at_)ebone(_dot_)net (Sean Doran) writes:
This link-hiding implies lots of levels [Kleinrock & Kamoun], which means
that either you have the same problem as Geoff in his most recent message
(i.e., you have to do a lookup and keep the result along with the
packet, or lots of lookups, or both), or you need a way to encode
per-level information in the address such that it looks something
like [<L1-address>.<L2-address>.<L3-address>...<LN-address>].
The problem is that 128 bits or about 64 bits, depending on what
semantics you put onto the addresses, is not very much room to
encode *anything near* the number of levels K&K hierarchical network
optimality calls for in the Internet,
Who says you need to use the IP addresses for that purpose? There is
plenty of precedent -- for a a long time we've had this notion of the
routing protocols adding labels on that had nothing to do per se with
the IP address. See the "AS" notion, for example, in which we label
various clouds with AS numbers, which are never seen by end users. It
would be straightforward enough to build a labeling scheme that was
used inside the routing protocol that stayed inside the routing
protocol. You could happily label the nodes of the routing cloud with
whatever numbering/labeling scheme you like.
If you find yourself wanting to add information like that to the
packets to help them wind their way through the network rather than
simply having the routers keep that information in hand, v6 will
happily let you tag on an option with such information as you enter a
routing cloud that needs it, or one could use encapsulation
mechanisms, putting the data "around" the packet.
In other words, v6 has neither helped nor hurt the routing problem --
it is orthogonal.
--
Perry E. Metzger perry(_at_)wasabisystems(_dot_)com
--
NetBSD Development, Support & CDs. http://www.wasabisystems.com/