|Thread Links||Date Links|
|Thread Prev||Thread Next||Thread Index||Date Prev||Date Next||Date Index|
To those concerned about XLAUI/CAUI,
In general, we are supportive of the Piers Dawe
presentation (dawe_03_0109.pdf) entitled “Compliance points for
XLAUI/CAUI with connector” to be given next week in
We believe the portion of the loss budget for the system host board should be as large as possible, since the overall solution includes the system host board and the module. In consideration of cost, the system host board will have far greater incremental cost than the module when higher quality PCB material is used. Cost sensitive applications using 40G interfaces will employ many such interfaces, which require fanning out signals to an array of 40G interfaces. This fanning out also places a requirement for longer system host-board trace lengths or higher system host-board loss, which again prompts the need to use higher-cost lower-loss-rate PCB and/or higher-cost manufacturing methods.
We wish to see the system host-board loss be 8.2 dB. However, we would continue to be supportive of the XLAUI/CAUI specification down to 7.5 dB for the system host-board loss.
In addition, since the Tx and Rx traces are segregated, FEXT is more important than NEXT. Thus, we would like to see the specification cover FEXT. Frequency dependent masks should actually be specified for both FEXT and NEXT.
Jeffery J. Maki, Ph.D.
Principal Optical Engineer
Juniper Networks, Inc.
(Please leave messages by email.)
IEEE 802.3 voter, OIF voter, & EA alternate voter
Member of OSA, LEOS, & IEEE
From: Ryan Latchman [mailto:Ryan.Latchman@xxxxxxxxxx]
In order to include a chip to retimed module specification in 802.3ba, application level input is required on expected module trace lengths, host trace lengths, numbers of via, etc. for 40GbE and 100GbE. It would be extremely useful if this information can be provided in terms of loss.
The XLAUI / CAUI team would appreciate any feedback in this area. To start the discussion Chris Cole has already submitted the following input in Comment 295:
Max module trace length 3”
From: Ryan Latchman
Hi Ali, Chris,
This is an important discussion which needs to get resolved quickly.
I would like to ensure that XLAUI / CAUI maintains its broad market applicability as a simple retimed interface. I don’t think the current specification methodology prevents it from being leveraged to build retimed modules. I’ve put together the attached material to show how retimed interfaces were specified in the past (namely XFI). In XFI, you’ll notice that the Before Connector and After Connector specs are similar. 40/100GbE modules may have an analogous situation, depending on their size and electrical characteristics.
If we need to change the XLAUI / CAUI specification, we need solid contributions on what needs to change.
From: Ali Ghiasi [mailto:aghiasi@xxxxxxxxxxxx]