Re: Re:loc/id vs HIP (was: tunneling [Was: Agenda for Vienna])

[Pekka Savola <pekkas@netcore.fi>]

On Thu, 22 May 2003, Ralph Droms wrote:
> > On 22 May 2003, marcelo bagnulo wrote:
> > > > Again: this doesn't solve the whole problem.  Consider e.g. Craig's
> > > > traffic engineering requirements, or (to a lesser degree) requirements
> > > > that the nodes should not have to renumbered ("deploying/retiring
> > > > locators") when the ISP's are changing.
> > >
> > > A comment about the renumbering issue.
> > > First i do not think this is part of the multi-homing issue, so if we
> > > find a solution that does not solve this i would say it is ok.
> >
> > Well, I think it is, practically, to an extent.  If Site is multihomed
> > using two prefixes to two providers, and wishes to switch the second one
> > to a better one, this should not be an overwhelming task (otherwise folks
> > might not want a multi-address solution in the first place).
> 
> How is the scenario you describe (switching one of two prefixes)
> different - in its effect on renumbering - from switching a site's only
> prefix?
>
> Multi-homing might make renumbering *easier* - providing one reliable
> address while renumbering the second...

This depends on what you count in in the renumbering issue.

There are two cases when you switch one ISP:
 1) completely removing the first ("disconnecting from the Internet"), 
then adding the second, and
 2) trying to run the first simultaneously with the second, and when the 
second works, disconnect the first.

1) above is "easier" to accomplish as the connections will die by 
definition, you have to spend time with configuration etc. -- but more 
harmful for the network.  You really don't have to care about complex 
things such as which prefixes are used etc.

2) is actually quite similar to "multihomed continuum" where you change 
only one of them, with the difference that you're not going to remove the 
first prefix in the end.

After some thinking, I can't quickly find major differences between 
multihomed renumbering and 2).

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings