RE: RTTP-- any comments?

From: Eugene Leitl (
Date: Wed Mar 28 2001 - 09:38:31 PST

On Wed, 28 Mar 2001, Mark Day wrote:

> Oh, c'mon. How can anyone be talking about the "possibility" of
> real-time data transmission over IP?

I don't think IP is suitable for hard realtime/QoS multi-hop transmission
at high (>>1 GBps) data rates. What you need is a protocol which is
cut-through capable with (hitherto mostly mythical) purely photonical
switches. I.e. deciding which link to switch to while the headers are
still cruising through a (short) fiber optic loop (acting as optical delay
line), while using low total numbers of optical switches (these things are
big and power hungry, since using NLO), using shallow gate hierarchy (gate
switch delays do accumulate).

Ideally, you preallocate crossbar bits with a temporal lock (built-in bit
rot implemented in hardware, path preburned through with admin messages
sent ahead), then stream it through, with the headers sorted in the right
sequence (sender smart, router dumb) so that the header bits directly
switch the crossbar, being consumed in the process (thus needing a very
shallow optical FIFO, if any).

If a bit lock decays before you're able to transmit, then you fallback to

This archive was generated by hypermail 2b29 : Fri Apr 27 2001 - 23:15:05 PDT