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About breakout objective, to support lower rate than 400Gbps, it is kind of close to the multi-rate(40/100Gbps or other rate) proposal
in 400GE we presented in some points. From logic architecture perspective, if we make 400GE breakout feature compatible with 40/100GE, it is not "trivial" for the architecture
at all. but if we introduce a new PMD other than 40/100GE 802.3ba/bj/bm, as scenarios #4 on page 9 of the slides linked , it already raised doubt about whether this is out of the scope of 400GE standard during discussing in "logic" ad hoc teleconferene. http://www.ieee802.org/3/400GSG/public/adhoc/logic/jun26_13/wangt_01_0613_logic.pdf On the other hand, from the logic implementation point of view, page 9 of the following link provides some compasions about logic resource cost and implementation
for different solutions, to support 4x100GE and 1x400GE. Breakout like feature is mainly an implementation issue and should be considered in TF proposals and may not be constrained in 400GE standard work. Breakout
objective in logic layer will introduce more complexity in architecture and bring difficulty to TF. http://www.ieee802.org/3/400GSG/public/13_09/wang_400_01_0913.pdf Also I think in parallel fiber PMDs, breakout feature is almost easy to have and useful to expand corresponding market scope. Best Regards Xinyuan Wang From: Brad Booth [mailto:bbooth@xxxxxxxx]
John, While I understand the intent of this objective (and agree implementation of this functionality would be good to have), I'm not sure how the task force satisfies this objective.
To provide breakout functionality such as 40G operating as 4x10G, the device operating in 40G mode complies with the 40G standard and when the device operates in 4x10G mode, does each 10G portion comply with the 10G standard? As
an example, 40GBASE-SR4 has a different reach requirement than a 4x10GBASE-SR. Which reach requirement is required for compliance? This is strictly an implementation decision. There is nothing within the 40G specification or the 10G specification that implies
any requirement for 40G to breakout to 4x10G, which permits some flexibility in implementations. Considering there are already 40G MAC/PHY and 100G MAC/PHY drafts or specifications in 802.3, how does a 400G MAC/PHY standard create compliance with those specifications? Does the "provide appropriate support" give the
task force the ability to create new 40G MAC/PHY or 100G MAC/PHY specifications that are derivatives of the 400G MAC/PHY specifications? For example, if the 400G SG has a 2 km SMF objective, does that mean that to provide appropriate support for breakout that
there would be the ability to create a 100G 2km SMF PMD? Implementation of breakout functionality is a great way to provide a migration path and I believe the TF should take that into consideration when selecting PHY proposals; I'm just not sure how the study group defines
it as objective the TF can show has been met. Your thoughts/feedback on this would be greatly appreciated. Thanks, Brad On Wed, Oct 16, 2013 at 6:15 AM, John D'Ambrosia <John_DAmbrosia@xxxxxxxx> wrote: All, Per our call last week, what are the thoughts on the wording of this as a proposed objective –
Provide appropriate support for breakout functionality to 40G and / or 100G There was some concern about potential impact or unintended consequences that people wanted to see this wording to discuss further. Regards, John |