[9fans] on TCP vs IL

[ggm@apnic.net (George Michaelson)]

To be fair, I suspect many who wish to complain of TCP actually
are complaining of sockets.

If you remove the I/O abstraction from consideration, I personally think
you're left with a transport layer which is less like an egregious
collection of hacks and tweaks, than a reflection of the history of
knowledge about large dynamic networks. For IPv4, if people had known a
bit more about what was coming, I think they too would have simplified
rather than accreted. Certainly what little I hear at IETF suggests that.

Maybe Plan 9 can leapfrog into IPv6 and get a clean stack on a protocol
which has efficient header layout, embedded IPSEC, and some rather
interesting re-addressing and host/self-discovery features. Not to
mention gorgeously huge address-space, which makes for consideration of
interesting mappings of persistant datastore into the network address space.

In designing IL over IP, I suspect the network transport people face the
same problems TCP does. To argue successfully for a *radically*
different approach demands a bit of rigour. What is the core abstraction in
IL which makes it so compelling? Whats its addressing schema in the packets.
What does it offer routers in terms of knowledge of end-to-end flows, or
in proving for the Clark end-to-end model irrespective of the attempts to
make routers over-smart?

The roadside is littered with very interesting transports. I speak not
of OSI, but perhaps ST-II or RSVP comes to mind. ST-II was not designed
by dumbheads, (I think it behoves us to respect the smarts of IBM
research, even if we don't agree with their corporate outcomes) Likewise
multicast has to be faced as a very compelling story in distributed
data.

There are reasons we don't all run over Chaosnet/XNS or dare I say it
Appletalk, or DECnet and they aren't just to do with economics or
political computing history. These protocols didn't provide enough
operational flexibility to scale worldwide or off-planet. And to bring
OSI back into the equation, Its pretty clear the stack as a whole was a
write-off for all but academic theorizing, but some core components such
as IS-IS are really quite respectably useful.

cheers
	-George