Re: A tunneling proposal

[Ramakrishna Gummadi <ramki@cs.berkeley.edu>]

> > Economics is a major constraint on the potential solution space.
>
> I'm not even talking about economics, but just basic functionality and human
> nature: how are you going to convince someone stop doing something that works
> for them to help some greater good, that doesn't show obvious signs of
> needing help? "Global warming? Let me turn up the airco..."
>
> If there really is a limit above which global routing breaks down, we should
> implement some policies to prevent the number of routes from reaching this
> limit. This means forcing existing ASes to aggregate, and limiting the growth
> in the number of ASes. That way, SCTP-like solutions become more attractive.
>

Currently, multihomers pay each their ISPs extra to carry non-aggregatable
routes. This means if the ISPs encounter problems with the
additional routes, they are directly going to charge the sites
more. This way, one can impose artificial constraints on how
many sites multihome, but this is exactly what we are trying to avoid.

As for backpatcing TCP to work with multihoming, this would
not work with the current apps, and socket API if done the SCTP
way---SCTP requires the apps to *explicitly* give a list of addresses
to use on a connection. To backpatch TCP to do the same would mean
requiring the TCP layer itself to figure out what additional addresses
it can use *without* the app knowledge. This means that the protocol
stack can get it wrong if there is address translation going on
for getting provider independence, etc...
Ultimately, it will basically look like GxSE...

-ramki