[e2e] "PMTUD using options" draft

[Christian Huitema]

> > It is widely believed that all routers process IP packets
> > with options in the "slow path", as you claim in your web
> > site above.  This should be re-filed in the basket of
> > "widely believed fallacy". :-)
> >
> > In fact, this is no longer true (if it ever was).
> 
> Okay, so you say that this '"fallacy"' is not true. And suggest that
> it may never have been true.

I have no reason to not believe Ran, and to accept that some routers can
process some options without any performance penalty. I am not sure that
these routers can process every option that can possibly be invented.
But as Lloyd points out, there are quite a few routers out there that
cannot process the options in real time. Maybe they are using inferior
and obsolete technology, but there is a good chance that there will be
one such router on any given path.

If you use an IP option and there is an ancient router on the path, that
router will become your bottleneck, and your performances will be
terrible. Thus it is only safe to use options when all routers have been
replaced. In short, we have a classic "boil the ocean" scenario. We have
to boil the entire ocean, i.e. replace all the routers, before we can
cook a single noodle, i.e. use IP options.

-- Christian Huitema