[BBLISA] anybody doing IPv6 for real operations?/possible presentation topic

[Dean Anderson]

On 14 Mar 2010, Daniel Hagerty wrote:

>     He's talking about using IS-IS as a unified, multi-protocol IGP.
> This is being done in production networks, today.

Yes.

>     He does seem to be claiming that you can use IS-IS to forward IPv6
> without enabling IPv6 on the router, but that would indeed be magic,
> and isn't how it works.

No, that's not what I mean. I mean: In OSPF, if a route has an unknown
interface type on some router, it is dropped, and won't be propagated.  
So to add a new interface type to the network, you have to upgrade OSPF
on every router in the network.  This is with IPv4. There is no way that
OSPF could ever be a multi-protocol IGP.

IS-IS can handle routes with unknown interface types. IS-IS can handle
multiple protocols.  As a link-state IGP, IS-IS does everything OSPF
does, including virtual links, etc.

>     Dean clearly doesn't like the "ships in the night" style of
> routing protocols that the IETF produced.  Perlman can probably
> discuss the tradeoffs between "ships in the night" and integrated
> routing a little bit more clearly, should you care about that layer of
> the debate.

I did. I switched jobs (to OSF from Draper) in 1989 to get on a 56kbs
Internet connection.

>     If you're being more pragmatic, IPv6s routing options are pretty
> much the same as IPv4.  There's a RIP, there's an OSPF, there's ISIS
> if you don't like a routing protocol per network protocol.  BGP can be
> handled in a more integrated fashion, although some prefer an enforced
> "ships in the night" of only talking about IPv6 over IPv6.

Technically, there are independent variants of each of these protocols,
each with their own duplicated overhead. Your OSPF6 configuration can be
mismatched to your OSPF configuration.  Its possible that IPV4 can reach
a physical network, but IPv6 can't, because of some problem.  And with
OSPF6, there are a *lot* of potential problems.  Does your router have
host routes?  Does some other router have host routes?  Do they
inter-operate? etc.

Poor and fluid specification has made a number of problems, and the 
withdrawal of some pie-in-sky features (eg host routes) has left a lot 
of inter-op. problems.

By contrast, IS-IS handles multiple protocols in one process with less
overhead.  Configuaration & route distribution is always consistent.  
There are no inter-op problems, and we know its going to work.  Its a
no-brainer to use IS-IS instead of OSPF4 and OSPF6 together.  So once
you see that no brainer, the next obvious no-brainer is to use CLNS
instead of IPV6.  Once again, all the benefits of IPV6, none of the
drawbacks.  There are no inter-op worries with CLNS.


		--Dean

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