IPv4 address length technical design

Eugen Leitl eugen at leitl.org
Thu Oct 4 06:47:45 UTC 2012


On Wed, Oct 03, 2012 at 06:59:20PM -0400, Valdis.Kletnieks at vt.edu wrote:

> Where's Noel Chiappa when you need him?
> 
> >   (2)  The new protocol will use  variable-length address for the Host
> > portion, such as  used in the addresses of CLNP,
> 
> This also was considered during the IPv6 design phase, and the router
> designers had a collective cow, as it makes ASIC design a whole lot more
> interesting.  And back then, line speed was a lot lower than it is now...
> 
> Not saying it can't be done - but you're basically going to have to do CLNP
> style handling at 400Gbits or 1Tbit.  Better get those ASIC designers a *lot*
> of caffeine, they're gonna need it...

Except that these will be pure photonic networks, and apart from optical
delay lines for your packet buffer you'd better be able to make a routing 
(switching) decision while few bits of the header have streamed by your
photonic router circuit.

There is no time for any table look-ups, obviously.

And optical gates are *really* expensive, so better use few of
them. And don't add too many gate delays, too.

Above describes your setting for the next protocol. There is not
a lot of leeway in design space, I'm afraid.



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