Re: administrivia (on avoiding injury)

[Greg Maxwell <gmaxwell@martin.fl.us>]

County Commissioners.
On Tue, 10 Apr 2001, Jim Bound wrote:

[snip]
> We have no way today.  But this plays into other mail I just sent.
> ISPB would send Neighbor Discovery (ND) link-broken-ISPZ to site and site 
> would send via ND host.  This would trigger at IP layer (quickest fix)
> that all packets to ISPZ would now go to ISPA.
[snip]

Well, it's not quite that simple:


   [.......world.............]
        /1   |2    |3     \4 
    [ISPA] [ISPB] [ISPC]  [ISPD]
       \5  /6  \7  /8 \9     /10
       [SITEA] [SITEB] [SITEC]

Would you like failue of link 2 to make SiteA<->SiteB go across the world
rather then ISPB.

Should a failure of 7 make SITEA not try to reach SITEC via ISPB?

The simplest, but lest efficent, method is for the hosts to attempt
retransmission across alternative pairs.

I think that should suffice for our purposes here.

In the future I think that negitive ND type messages will accelerate and
make such things more efficent. Also, packet loss will more likey be a
sign of failure (or really really bad congestion) if ECN is widely used,
so more agressive path change could be triggered by it.

Unless someone has a theory as to what transport level multihoming is dead
without 'push' notification of link failure, or why it would have to be
implimented architecturally rather then as an improvement, we should
probably leave it alone.