And Now for Something Completely Different (was Re: IPv6 news)

Sun Oct 16 11:06:02 UTC 2005

On Sun, 16 Oct 2005, Mike Leber wrote:

> Does shim6 require new protocol stacks on the hosts at both ends of a
> session?  (If not then the source is not making its own path selection
> decisions.)

As I understood it, shim6 is a way for two hosts to communicate between 
each other that they have multiple IPv6 addresses. So if a timeout occurs 
to the last used address, you can try another and try to resume the 
communication.

So if the web-server has two different IP:s (from two different 
providers), both would be in DNS (preferrably) and the TCP session would 
be established with one of them. If shim6 detects that the original path 
is broken, it will try to use another and if it succeeds, the application 
won't notice anything as shim6 will abstract this to the TCP layer.

I think this is a really good idea, having the network know about all 
multihomed companies just doesn't scale. With less prefixes and less AS 
numbers, network convergance would be much better.

Think in the future, do we really want routers that'll handle millions of 
prefixes and hundreds of thousands of AS numbers, just because people want 
resiliance? If this can be solved on the end-user layer instead, it's more 
scalable. I can also see a loadbalancing scheme coming out on top of shim6 
that'll be usable to end users as well.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se