Re: delayed multihoming/mobility set-up

[Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>]

Christian;

> > > IvB>  The reason that BGP
> > > IvB> rerouting can take so long is that the RFC mandates a 90 second
> >
> > hold
> >
> > > IvB> time,
> >
> > And a 90 second hold time is already too long.

> ... which is why I am convinced that the solution to preserving existing
> communication is closest to "transport protocols" than "routing
> protocols".

As you say "preserving", you really are talking about "connection",
not "communication" in general.

The proper argument is that

	preserving existing connection is a function of not the
	connectionless Internetworking layer but the transport
	layer (or above)

But, note that your argument is insufficient ignoring simple UDP
query-response type communication such as that of DNS.

> The time scale of transport protocols is the RTT; the time
> scale of routing protocols is the minute. If we wait for a routing event
> to be somehow signaled to the transport stack, the connection will be
> gone.

The role of routing protocol is to try to keep the Internet
connected at the connectinless Internetworking layer, which
has nothing to do with connection of connection oriented
protocols.

In other types of network, routing protocols may operate both
at L2, L3 and L4 to take care of keep preserving L4 connection.
But, it is not the case with the Internet.

> I would note that a lot of the communication we have today do not meet
> the "worth it" requirement. The top applications in the Internet today
> are web pages, which mostly consist of a large number of very short
> exchanges, and p2p file sharing, which includes its own application
> level tools to deal with multi-homing.

You are connection oriented.

The difficulty is not in "preserving". See above for a UDP example.

							Masataka Ohta