shim6 @ NANOG

David Barak thegameiam at
Tue Feb 28 16:39:53 UTC 2006

--- Joe Abley <jabley at> wrote:

> On 28-Feb-2006, at 11:09, Kevin Day wrote:
> > Some problems/issues that are solved by current
> IPv4 TE practices  
> > that we are currently using, that we can't do
> easily in Shim6:
> Just to be clear, are you speaking from the
> perspective of an access  
> provider, or of an enterprise?

It's good to clarify that those are quite different
requirement sets.  One thing which Shim6 does not
provide easily is the ability for an enterprise to
have policy decisions made in a very limited number of
places - for instance, a customer has two Internet
pipes to two different providers to their DMZ.  Right
now, that means that BGP gets spoken by two routers
(maybe four at most), and all external policy
decisions happen there.  By moving the decision-making
to the hosts, it's possible to have different
decisions being made on each of the 85 webservers
being served by those two Internet pipes.

"But each of the servers is optimizing the path for
its own traffic"

Correct, but what if there are other policy goals? 
I.e. "don't use pipe 2 unless pipe 1 is full/down,
because it's more expensive" "only send low-jitter
traffic to pipe-2"

Whatever mechanism is selected, it needs to support an
intermediate-system-based routing decision algorithm,
not just an end-system-based approach.


David Barak
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