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Re: IPv6 Multi-homing BOF at NANOG 35

Cross posting removed - this is a mainstream shim6 comment...

Jason Schiller (schiller@uu.net) wrote:
...

I hope the proposed BOF will make this clearer. I personally
think that shim6 will be really cool for ISPs, although as Geoff
says it will take a while to deploy and during that time we'll
need a PI-like approach.

    Brian



There are many content providers who are avoiding IPv6 as they beleive it
is not yet ready for "prime time" commerical traffic as it lacks sufficent
multi-homing capabilities.  Clearly we need a multi-homing solution
now.  However I am concerned that if we allow PI addresses into the global
routing table, then we begin down the path of solving the multi-homing problem by de-aggregating. In 10 years time, there may be many 
de-aggregates in the global routing table.  At that time it will be much
harder to tighten the belt and get those prefixes out of the global
routing table. 

Absolutely.



Do you think that operators of commercial networks will want to switch to
shim6?


They won't need to. Shim6 deploys in the hosts. An ISP doesn't have
to do a single thing to enable or switch to shim6. Customer sites with
two PA prefixes will just start multihoming. That's the beauty
of it.

A local ISP might decide to facilitate shim6 for the benefit of its customers
(i.e. the ISP plus its subscribers becomes a "site" in shim6 terms). That
ISP would indeed have to do something, but not much - advertise two prefixes
to its customers, who would thereby get 2N addresses where they had N
addresses before. Shim6 would do the rest in the hosts.

[In both cases I've skimmed over exit router selection issues, which
still needs work.]


Consider the current comfort level with the IPv4 style BGP
de-aggregate traffic engineering.  Consider that the current approach to
shim6 is less functional than the current IPv4 style multi-homing. 

I don't think that's true, from the requirements viewpoint
of the end user.


Consider the the shim6 solution may be very different to operate
(configuring end hosts instead of Internet facing routers) 

No configuration involved. Just a shim6 capable stack.


and may
break current operational boundaries. 

It seems more likely to make them irrelevant, to me.


Shim6 as a host multi-homing solution lends itself nicely to consumer
networks all operated by few end users with few hosts, but is more
problematic to implement it in a large commerical network.


I really don't see that, modulo the exit router selection issue.



Don't miss read me.  I'm not bashing shim6.  I'm suggesting it needs to be
as functional as what operators currently have. 
I'm also suggesting that there is a barrier to change, and if traditional
IPv4 style multi-homing is allowed to be done in IPv6 then comercial
networks may never adopt a shim6 solution.


They will have to, when PI scaling starts to break things.


ARIN is currently considerig PI IPv6 space.  See Policy Proposal
2005-1: Provider-independent IPv6 Assignments for End Sites:

http://www.arin.net/policy/proposals/2005_1.html

It is my belief that if this policy goes through that commercial sites
will
be unlikely adopt a shim6 solution. 

There's a big difference between what major sites with the weight to
get their prefix advertised can do and what small and medium businesses
without such weight can do. I don't doubt that a few thousand major
corporations will end up with PI-like solutions. I know that won't happen
for tens of millions of small and medium businesses. I hope that ARIN
and all the RIRs move very carefully, for that reason.

   Brian