Multi-6 [WAS: OT - Vint Cerf joins Google]

Mon Sep 12 23:29:16 UTC 2005

> Whilst this thread is open... perhaps someone can explain to me how
> shim6 is as good as multihoming in the case of redundancy when one of
> the links is down at the time of the initial request, so before any
> shim-layer negotiation happens.
> 
> I must be missing something, but there's a good chance that the
> requester is going to have to wait for a timeout on their SYN packets
> before failing over to another address to try.   Or is the requester
> supposed to send SYNs to all addresses for a hostname and race them off?

There are a variety of possible implementations.  A full timeout and
serial retries are one extreme.  Trying all addresses in parallel is
another.  Anything in between is not out of the bounds of possibility.

IMHO, the thing to do is to send out the first SYN and wait 1 RTT, not a
full timeout.  Then, try two addresses.  After the next RTT, try four
addresses...  It's just binary exponential backoff of another flavor.  ;-)

My $.02,
Tony