Shim6, was: Re: filtering /48 is going to be necessary

Geoff Huston gih at
Mon Mar 12 22:19:00 CDT 2012

On 13/03/2012, at 2:31 AM, Leo Bicknell wrote:

> In a message written on Mon, Mar 12, 2012 at 11:07:54AM -0400, Robert E. Seastrom wrote:
>> Grass-roots, bottom-up policy process
>> +
>> Need for multihoming
>> +
>> Got tired of waiting
>> =
>> IPv6 PI
> I'll also add that Shim6 folks never made a good economic argument.
> It's true that having routes in the DFZ costs money, and that
> reducing the number of routes will save the industry money in router
> upgrades and such to handle more routes.  However, it's also true
> that deploying SHIM6 (or similar solutions) also has a cost in
> rewritten software, traning for network engineers and administrators,
> and so on.
> It was never clear to me that even if it worked 100% as advertised that
> it would be cheaper / better in the global sense.

I think that's asking too much of the IETF Leo - Shim6 went through much the
same process as most of the IETF work these days: bubble of thought, BOF sanity
check, requirements work, protocol prototyping, technology specification.

Yes, the economics of routing are strange, and the lack of any real strictures
in the routing tables are testament to the observation that despite more than
two decades of tossing the idea around we've yet to find the equivalent of a 
"route deaggregation tax" or a "route advertisement tax"  or any other mechanism
that effectively turns the routing space into a form of market that imposes
some economic constraints on the activity. So after so long looking for such
a framework in routing, the hope that someday we will figure it out
gets smaller and smaller every day.

And in some ways the routing explosion problem is one of fear rather than 
actuality - the growth rates of the IPv4 routing table have been sitting at
around 8% - 15% p.a. for many years. oWhile you can't route the Internet on 
15 year old hardware, the growth figures are still low enough under Moore's 
Law that the unit cost of routing is not escalating at levels that are
notably higher than other cost elements for an ISP. Its not the routing
table explosion that will cause you to raise your fees or worse, go 
bankrupt tomorrow.

So in some ways for Shim6 to have a "good economic argument" I suspect
that Shim6 would have to have pulled out of thin air an approach that
completely externalised the cost of routing, and made routing completely
free for ISPs. And that is simply fantasy land!



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