Re: IPv6 fc00::/7 — Unique local addresses

Thu Oct 21 02:15:35 UTC 2010

On Wed, Oct 20, 2010 at 8:46 PM, Matthew Kaufman <matthew at matthew.at> wrote:
> On 10/20/2010 6:20 PM, Mark Smith wrote:
> Right. Just like to multihome with IPv6 you would have both PA addresses
> from provider #1 and PA addresses from provider #2 in your network.
> Only nobody wants to do that either.

A perfectly valid way to multihome, right?    Setup each host with two
IP addresses,
one in each PA range.     Use multiple DNS records, to indicate all
the host's pairs of IPs.
If an ISP link goes down,  all the clients' should automatically try
resend the unack'ed packets to the
DNS name's  other IPs in 10 or 11 seconds, and recover, without having
to reconnect, right? right??    [ No   :(  ]

Automatic  failover to other multihomed IPs  seems to always have been
left missing from the TCP protocols, for some reason or another.

Probably good reasons, but that  multihoming strategy isn't a very
good one, for now,
due to the disruption of active connections,   and bad client
programs that won't look for other DNS records,
even when trying to establish a new connection.

Perhaps one day, there will be a truly reliable transport protocol,
and an  API  that allows a bind()
against multiple IPs and  a  connect()
to all a target host's IPs instead of just one, so both hosts can
learn of each other's IP addresses
that are offered to be used for that connection, then   "multiple PA
IP addresses"
would be a  technically viable multi-homing strategy.

--
-Jh