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Arthur, Clarification: - I support using Clause 73 AN for P802.3bj. - Sequence ordered sets could provide fast FEC on/off switching that having to restart AN. - Sequence ordered sets could provide a means to exchange FEC abilities, etc. in optical media. - Speed negotiation in optics could use parallel detect specified by 802.3ap. Hopefully that clarifies things a bit better.
From: Arthur Marris [mailto:arthurm@xxxxxxxxxxx] Brad, Let me make a few comments. For 802.3bj it is necessary to use Clause 73 for auto-negotiation because Clause 73 already supports port types for four-lane twinax and back-plane. If new 100G port types are being added for these media, they need to be included in Clause 73. Clause 73 also gives you FEC negotiation for free. Clause 73 clearly does not work over optical media. You can use ordered sets for exchanging ability and requests, but this only works if both sides of the link are running at the same speed and the error ratio is not too bad. For next generation optics you are going to need to decide whether you need to negotiate speed in addition to determining FEC operation (for example you might want to negotiate between 40GBASE-SR4 and 100GBASE-SR4). If you do decide to negotiate speed you could consider re-using Clause 37 for auto-negotiation (which operates at a 1.25G data-rate). If you are not negotiating speed but are just concerned about bit errors, then the task being performed is really link training rather than ability resolution. Arthur. From: Brad Booth [mailto:Brad_Booth@xxxxxxxx] Stephen, It depends on the FEC protocol adopted, implementation requirement, and the associated latency. The discussion got started around the idea of using Clause 73 AN for FEC ability exchange in the optical domain. Considering we’re still in the study group phase, some of those questions cannot be answered as we have not adopted an FEC proposal. If an exchange protocol is required, then IMHO the use of sequence ordered sets would be preferred over creating of a new autoneg protocol. Cheers, |