RE: Preserving established communications (was RE: about draft-nordmark-multi6-noid-00)

[Erik Nordmark <Erik.Nordmark@sun.com>]

> - But now you say that it would be better to work in BGP convergence, which
> is clearly out of the scope of the wg

FWIW I didn't suggest that this WG should work on improving BGP convergence
time.
But it is something that perhaps an other WG could do in combination
with operators and vendors.

> The result is that the solution than will not provide ULP session
> surviavility for a number of cases.

Since we haven't defined what session surviability actually means there
is a simple approach; use a multi6 solution with existing BGP and
set the time when TCP gives up to inifinite i.e. TCP will keep on
trying forever. That provides session suvivability.

While that might not be that useful, it does illustrate that the discussion
is really about the timelyness of failure recovery and not about whether
failure recovery is possible.

Perhaps having optional M6-layer heartbeat messages that
the ULP can enable by stating "I'd like failure recovery in 17 seconds"
would make sense.
As your examples point out this might still run into BGP convergence time
issues if all of the peer's locator prefixes are routed out the same
failed link/ISP.
But it might still be a step in the right direction in terms of abstracting
the "failure recovery" service offered by an M6 layer.

  Erik