Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: Connector Return Loss

Here are my views:
The 20 dB level for MM connectors is historical in that that has been the
spec used by previous generations of application standards and is in
agreement with cabling standards. 

The 26 dB level for SM connectors initiated in Fibre Channel in the early to
mid nineties. I believe this was at the request of 1300 nm transceiver
vendors. It is also in agreement with cabling standards. It is interesting
to not that Telcordia (formerly Bellcore) used 27 dB in the past, which I
believe was in concert with SONET equipment standards.

The use of isolators in the transceiver is a design choice and not dictated
by IEEE 802.3. The receiver is specified with a minimum return loss level,
the value of which has been the subject of debate.

What type of testing are you referring to? Transceiver or cabling?

Paul Kolesar
Lucent Technologies

	From: []
	Sent:  Wednesday, April 11, 2001 9:23 AM
	To:  802.3ae
	Subject:  Connector Return Loss

	Does anyone know the history behind the connector return loss
	proposed for 10 GbE?

	The return loss for multimode connections shall be greater than 20
	The return loss for single mode connections shall be greater than 26

	Do the transceivers integrate isolators into them to address return

	Has any testing be done to demonstrate compatibility?


	Doug Coleman
	Corning Cable Systems