Subject: RE: Notes about identifier - locator separator

From: "Christian Huitema" <[email-masked]>
Date: Fri, 8 Nov 2002 12:29:04 -0800

> > The IPv6 architecture is pretty clear about that one: the only
packets
> > that a router is expected to process are those in which the first
> > payload is a "per hop option", or those in which the destination
address
> > is one of the router's own addresses. All other payloads are
supposedly
> > end-to-end.
> 
> 
> Well there's architecture and reality.  Reality says that devices are
> going to look well inside the header for port information, firewall
> processing, and packet classification, to name a few.

Sure. But Frank originally mentioned VLSI. Hard-coding this kind of
"value added" filters in a VLSI doesn't look like a terribly good idea.
Also, there is the little detail called IPSEC...

-- Christian Huitema

---

From: "Tony Li" <[email-masked]>
Date: Fri, 8 Nov 2002 13:57:40 -0800

|   The presence of IPv4 options in a packet header cause the IPv4
|   packet to be kicked out of the silicon-path of many of today's
|   high speed routers. Given that history, I could easily forsee
|   a silicon-forwarder for IPv6 that kicks packets to the slow
|   path if the next-header field is _not_ one of several known
|   values (on the theory that if the next header is not X, Y, or Z
|   then there _might_ be something in there that the router needs
|   to look at...). This has undesired effects on throughput.

That's _today's_ routers and it's an optimization that makes sense
because there are no heavily used options.  If there were, then
folks would figure out how to do those options in hardware.  

Let's not let the tail wag the dog here, please.  If we need an
option that runs fast and can specify it, then it can be done
in hardware.

Tony