Re: delayed multihoming/mobility set-up

[Dave Crocker <dhc@dcrocker.net>]

Iljitsch,

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

The reason that BGP has a long hold is because short times lead to route
flapping.

This is an inherent property of doing route calculations.  A scheme that
is too quick to change will be constantly changing.  Hence the
assessment of a particular route always needs to be pretty slow to
change the assessment.

That is why I think the way to achieve quick response is with a model of
parallel paths.  When one goes out, the other is already in use.  (Of
course, this introduces the costs of out-of-order packets.)


d/
--
 Dave Crocker <dcrocker-at-brandenburg-dot-com>
 Brandenburg InternetWorking <www.brandenburg.com>
 Sunnyvale, CA  USA <tel:+1.408.246.8253>