shim6 @ NANOG (forwarded note from John Payne)

Randy Bush randy at
Wed Mar 1 23:29:34 UTC 2006

>>> How about some actual technical complaints about shim6?
>> good question.  to give such discussion a base, could you
>> point us to the documents which describe how to deploy it in
>> the two most common situation operators see
>>   o a large multi-homed enterprise customer
> There are no documents describing deployment. Probably there should be.
> The general approach is presumably well-known (for those for whom it  
> is not, go browse around < 
> charter.html>, and perhaps in particular < 
> internet-drafts/draft-ietf-shim6-proto-03.txt>.
> Deployment in an enterprise is a matter of:
>   (a) deploying hosts with shim6-capable stacks within the enterprise;
>   (b) arranging for those hosts to receive addresses in each PA  
> assignment made by each transit provider (multiple PA addresses per  
> interface), e.g. using dhcp6;
>   (c) optionally, perhaps, installing shim6 middleware at some  
> suitable place between host and border in order to impose site policy  
> or modulate locator selection by the hosts.

and this last will handle the normal site border (and these days
intra-site, e.g., departmental, borders) issues such as
  o dns within the enterprise is isolated from that of outside
  o firewalls, algs, and sometimes nats
  o security policy in general
  o load balancing between upstreams
  o ...

i.e, what handles the impedance mismatch between the goal, which
is *site* multi-homing, and the tool, which is *host* multihoming?
and how does it handle it, how is it managed, ...?

> You will note I have glossed over several hundred minor details (and  
> several hundred more not-so-minor ones). The protocols are not yet  
> published; there is no known implementation.

possibly this contributes to the sceptisim with which this is viewed?

>>   o a small to medium multi-homed tier-n isp
> A small-to-medium, multi-homed, tier-n ISP can get PI space from  
> their RIR, and don't need to worry about shim6 at all. Ditto larger  
> ISPs, up to and including the largest.

as it is not yet clear if small isps can get pi space, and the issue
of multi-homing is central to the discussion of this issue, and
routing table growth is another vector here, perhaps this needs to be
explored a bit more.


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