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In essence, this is placing the burden on the subset of PHY implementers. I'm not advocating a PHY that works at two rates, I'm advocating a MAC/PLS that works at one rate - 10Gb/s. The PHY's would map the MAC/PLS data rate to their corresponding data rate, and in this architecture, only the WAN PHY would have to do something special to decrease the data rate to 9.58464 Gb/s. Maybe a new PHY sublayer is necessary to perform the data rate mapping.
I don't think we require two separate PARs because of the differences in a LAN PHY compared to a WAN PHY. What I believe is required is to isolate where the differences between these two types of networks are, and I believe that can be done by having a LAN PHY and a WAN PHY. To the system designer, the implementation becomes easier if they can pick a 10GbE MAC and plug it to a PHY of their choosing. The PLS service interfaces are the same and the operations inside the MACs are the same, only the PHYs are different: one is LAN capable, and the other is WAN capable. Keeping this all in one PAR can help to guarantee this interoperability of MAC, PLS and PHY.
Level One Communications, Austin Design Center
(512) 407-2135 office
(512) 589-4438 cellular
From: Jaime Kardontchik [SMTP:kardontchik.jaime@xxxxxxxxxxx]
Sent: Thursday, July 22, 1999 1:03 PM
Subject: PHYs with 10.000 and 9.584640
Hello Brad and other 10G'ers:
This looks to me like throwing the problem to the subset of PHY
since the HSSG (read subset of marketing, system and MAC engineers) does
not know how to solve the impasse and get the 75 % approval to either
10.000 or 9.584640 Gbps.
Are these PHYs going to be capable of sending/receiving both at
10.000 and 9.584640 Gbps ? This would appear to contradict the
accepted idea in the HSSG that the future standard should be
either 10 or 9.584640 (exclusive, but not both).
Are we going to define separate PHYs, one for 10.000 and another
for 9.584640 Gbps ? Then perhaps it would be better to define two
separate PARs and working groups, since behind these two different
clock rates are hidden many additional differences (it is not just
choosing between short-wave or long-wave laser PHYs).
Jaime E. Kardontchik
San Jose, CA 95131
> -----Original Message-----
>From: Booth, Brad [mailto:bbooth@xxxxxxxxxx]
>Sent: Wednesday, July 21, 1999 9:22 PM
>Subject: RE: 9.584640
>I really liked the proposal that Kevin Daines put on the overhead. One
>the reasons that I liked the proposal is that it matched what I
>my mind. :-) But there were other technical reasons why I liked it.
>proposal for those that missed it was to leave the MAC/PLS data rate at
>Gb/s, but to have the PHYs determine what data rate was required. In
>case of a LAN PHY, the data rate would be 10.0 Gb/s... a direct match
>MAC/PLS data rate. In the case of a WAN (or OC-192) PHY, the data rate
>would be 9.58464 Gb/s and the PHY would obtain that data rate by either
>form of flow control or buffering scheme.
>I like this because it allows the LAN architectures to remain cost
>while offering the ability to easily concentrate links (i.e. ten 1 GbE
>map nicely into one 10 GbE link). This architecture puts a bit of a
>burden on the WAN PHY, but I think that this still results in a cost
>effective solution for OC-192. The WAN solution may not be as low cost
>the LAN solution, but show me a Gb/s WAN solution today that is as cost
>effective as a Gb/s LAN solution.
>The other part that I like is that the only real difference between the
>and LAN solutions in Kevin's proposal is the PHY. Everything above the
>(including interface to PHY) remains relatively unchanged. Yes, it's
>going much faster, but that's an implementation issue, not a standards
>issue. At least that's my impression. :-)
>Just my 2 cents worth,
>Level One Communications, Austin Design Center
>(512) 407-2135 work
>(512) 589-4438 cell