Subject: [Hubmib] (Speculative) 10GbE management, UDLR

From: Chuck Harrison <[email-masked]>
Date: Sun, 21 Apr 2002 11:27:30 -0700

Ladies & Gents,

Please accept apologies if this posting is too far off topic or is
better raised elsewhere.

The motion picture production industry is in early stages of
defining methods for moving high-resolution uncompressed image
data between equipment (such as film-to-video scanners -- a.k.a.
telecine -- and disk arrays). The desired data rates are
typically in the 3 - 8 Gb/s range. Solutions based on anticipated
availability of merchant-market 10Gb Ethernet may be attractive.

Within today's postproduction facilities, data rates up to
~ 1.5 Gb/s are commonly handled with point-to-point coax links
using SMPTE 292M modulation which is "framed" as a video raster
and operates at 1.485 Gb/s. This is an HDTV standard and is
strictly unidirectional from the source to the receiver.
Unidirectional links can easily be "split" through distribution
amplifiers and can be routed to multiple viewing monitors and
destination equipment bays.

It is common for some types of motion picture postproduction
equipment to have Ethernet interaces for communications and
control functions, separate from the datapath used for bulk
video data. Some users have suggested that the low-cost
10/100/1000 Ethernet connection could be used to manage a
separate unidirectional 10Gb/s transmitter or receiver which
is dedicated to realtime video content.

The attached file shows a highly speculative protocol stack
for real-time operation of a telecine film scanner. The very
bottom of the diagram is of concern here. Note that RFC3077
Unidirectional Link Routing is suggested for dividing traffic
between the 10GbE and 10/100/1000 links. 802.3 bonding or
"trunking" of multiple 10GbE links could be applied if it
is necessary to scale to higher data rates.

A 10GbE transceiver in full compliance with 802.3ae will not
operate as a unidirectional transmitter, as the lack of light
from a receive fiber will create a fault condition which is
reflected out the transmit port. However, an implementation
for this application might intentionally ignore the receive
fault and transmit unidirectionally. I believe that SNMP
management would be pertinent to such unidirectional
ethernet implementations. RFC3077 proponents such as
http://www.udcast.com/udlr/ may suggest other applications
in which these management tools would be useful.

Individuals who are interested in the motion picture
postproduction interconnect problem may wish to contact the
SMPTE N26 or DC28 committees,
http://www.smpte.org/engineering_committees/ .

Thank you for your attention.

Cheers,
  Chuck Harrison
  Far Field Associates, LLC
  +1 360 863 8340 (voice)  PDT = GMT-0700