RE: FC encapsulation

[Robert Snively <rsnively@Brocade.COM>]

> 
> Is there a fundamental reason why the FC encapsulation draft
> does not include class 1?  The Fibre Channel standards (as far
> as I can tell) do not exclude the possibility of allowing
> class 1 connections through a fabric, so regardless of the intent
> of the FCIP, IFCP, and mFCP encapsulations, I do not see why
> this draft should exclude class 1.

Yes, there really is a fundamental problem.  Class 1 switch
behavior makes a full bandwidth lossless circuit connection
between one Fibre Channel node and another.  If you push exactly
1 Gbit into it, it SHALL push exactly 1 Gbit out, totally in order and
without loss and with low latency.  It will also change 
from one circuit connection
to another rather dynamically under Fibre Channel protocol 
control, with extremely low connection latencies.

TCP/IP simply does not provide those capabilities, so we never
even considered including it.  Class 6 is a clone of Class 1 in
those respects.  Class 4 has the same general properties, but
with clocked fractional bandwidth, so it has the same problems.

This did not upset most Fibre Channel implementers because all
the key applications that could truly exploit those additional
capabilities provided by TCP/IP were all implemented in Class 2
and in Class 3.  The few highly specialized legacy applications
that used Class 1 were perfectly happy with no IP connectivity.

Hope that is some help,

Bob Snively                        e-mail:    rsnively@brocade.com
Brocade Communications Systems     phone:  408 487 8135
1745 Technology Drive
San Jose, CA 95110