shim6 (was Re: IPv6 news)

Fri Oct 14 19:19:27 UTC 2005

On 14-Oct-2005, at 14:48, David Conrad wrote:

> On Oct 14, 2005, at 7:57 AM, Joe Abley wrote:
>
>> The big gap in the multi-homing story for v6 is for end sites,  
>> since those are specifically excluded by all the RIRs' policies on  
>> PI addressing right now. Shim6 is intended to be a solution for  
>> end sites.
>
> Since shim6 requires changes in protocol stacks on nodes, my  
> impression has been that it isn't a _site_ multihoming solution,  
> but rather a _node_ multihoming solution.  Is my impression incorrect?

There is no shortage of rough corners to file down, and I am behind  
on my shim6 mail, but the general idea is to let end sites multi-home  
in the "bag-o-PA-prefixes" style and let the nodes within that site  
use their multiple globally-unique addresses (one per upstream, say)  
to allow sessions to survive rehoming events.

>> Are you suggesting that something else is required for ISPs above  
>> and beyond announcing PI space with BGP, or that shim6 (once baked  
>> and real) would present a threat to ISPs?
>
> If my impression is correct, then my feeling is that something else  
> is required.  I am somewhat skeptical that shim6 will be  
> implemented in any near term timeframe and it will take a very long  
> time for existing v6 stacks to be upgraded to support shim6.  What  
> I suspect will be required is real _site_ multihoming.  Something  
> that will take existing v6 customer sites and allow them to be  
> multi-homed without modification to each and every v6 stack within  
> the site.

For end sites, that's a wildly-held opinion.

For ISPs, it's not required, since ISPs can already multi-home in the  
manner you describe, using PI addresses and BGP.

Joe