shim6 @ NANOG (forwarded note from John Payne)

Joe Abley jabley at
Wed Mar 1 16:46:26 UTC 2006

On 1-Mar-2006, at 11:22, David Barak wrote:

> Also, the current drafts don't support middleboxes,
> which a huge number of enterprises use - in fact the
> drafts specifically preclude their existence, which
> renders this a complete non-starter for most of my
> clients.

I have not yet reviewed the lastest shim6 protocol draft, but I've  
seem discussion around it in which people have talked about middlebox  
support (in the context of "do we want to leave the door open to  
middleboxes, or should we insist that this is all done on the host  

> My single biggest issue here however is the
> complexity: given that today's architecture can
> deliver relatively simple and robust multihoming to
> enterprises, and rerouting DOES work today for
> persistent sessions (albeit imperfectly), what is the
> benefit to be gained from doing something this hard?

The current system is complex too, and it will get more complex as  
the amount of state in the routing system increases. Contrary to what  
some might think, reading this thread, inter-domain traffic  
engineering is only achievable using BGP in fairly coarse terms, and  
the success or failure of the TE tweaks in terms of the desired  
outcome is often non-determinstic, depending on it does on the  
routing policies of others.

The current system has the advantage, of course, that its strengths  
and weaknesses are somewhat well-known.

> As far as I can tell, the whole reason for these
> discussions is the insistence on the strict
> PA-addressing model, with no ability to advertise PA
> space to other providers.

The whole reason for the strict PA-addressing model is concern over  
whether open-slather on PI address space will result in an Internet  
that will scale.


(Failing miserably to keep quiet. Must try harder.)

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