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

  • From: Mike Leber
  • Date: Sun Oct 16 05:08:39 2005

On Sun, 16 Oct 2005, Joe Maimon wrote:
> Tony Li wrote:
> > It's just a mess.  I think that we all can agree that a real locator/ 
> > identifier split is the correct architectural direction, but that's  
> > simply not politically tractable.  If the real message that the  
> > provider community is trying to send is that they want this, and not  
> > IPv6 as it stands today, then that's the message that should be sent,  
> > without reference to shim6.
> > 
> > Tony
> How is a split between locator / identifier any different logicaly from 
> the existing ipv4 source routing?
> I thought that got dead ended?
> Or is a table lookup going to be needed?
> Wont all those tables need to be in the exact (or close to) same place 
> as the current routing tables?
> Appreciate any enlightenment.

For example, if your goal was to have TCP-like sessions between
identifiers survive network events without globally propagating full
network topology information about your site (the gripe against classic
IPv4 BGP) you could have multiple locators associated with any single
identifier sort of like the same way you can have multiple A records for a
domain name.  If the location layer session times out then it would try
the other locators listed (pick a method of selection) and if it suceeded
would resume the session transparent to the identifier layer. Design the
timeout and retransmit algorithm and parameters to achieve the convergence
times of your choice.

You would need a new protocol stack on the hosts at both ends of
connections.  By common convention classic TCP hosts could be told to use
one of the locators (a transition hack, or just run the protocols in
parallel).  No change would be required to the network, and existing TCP
could continue to be supported (no flag day).

Of course support of this new protocol would be limited to the clients and
servers that chose to implement it, however this is no less than the
change required for IPv6 which some hoped would solve the multihoming
problem (possibly defined as scalably supporting network topology change
without sessions being interrupted).


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