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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. Sincerely, Jeffery ——————————————————————— Jeffery J. Maki, Ph.D. Principal Optical Engineer Juniper
Networks, Inc. Desk +1-408-936-8575 Lab +1-408-936-1169 (Please leave messages by email.) FAX +1-408-936-3025 www.juniper.net ——————————————————————— IEEE 802.3 voter, OIF voter, & EA alternate voter Member of OSA, LEOS, & IEEE ——————————————————————— From: Ryan Latchman [mailto:Ryan.Latchman@xxxxxxxxxx] 802.3ba Colleagues, 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” Best Regards, Ryan 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. Happy Holidays, Ryan From: Ali Ghiasi [mailto:aghiasi@xxxxxxxxxxxx] Chris |