Re: On the use of multiple PA prefixes or a single PI prefix for IPv6 multihoming

["Michael H. Lambert" <lambert@psc.edu>]

On 22 Oct 2004, at 08:28, Iljitsch van Beijnum wrote:

> But the question is: will this help us or hurt us? Basically, BGP 
> doesn't really know what the best path is, but it can usually detect 
> and avoid the bad ones. So you pretty much always get something 
> reasonable. With multi-address multihoming you get many more paths, 
> some of which are better than what BGP would have given you, but a lot 
> are worse. So the trick is to select the best one, or at least avoid 
> the bad ones. How do we do this?

[Not directed at Iljitsch; just quoting his text]

Given that the "best path" probably just has meaning for a given 
application between given hosts at a given point in time, how often do 
we *really* need the *best* path?
Best effort usually works well enough for forwarding--why shouldn't it 
do the same for path selection? (I think Noel implied this in his 
response--to use his highway analogy: in driving from Boston to San 
Francisco saving six hours is good, saving ten minutes is (usually) 
irrelevant?)

Since the One True Best Path is likely unknowable anyway, why 
complicate path selection by building SVCs (or MPLS tunnels) into it?

Michael