With regard to your point 5a below, I was pointing out that to do framing,
either flow control (because of coding overhead) OR new packet formating
would be required at that point, even at the slower OC-192 payload rate.
I meant that this issue should be considered ALONG with the clocking issue.
From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxxxxx]
Sent: Thursday, July 15, 1999 3:17 PM
To: Hon Wah Chin; HSSG; Dan Dove
Subject: Re: 9.584640
Thanks for kicking this issue off again!
Hon Wah Chin wrote:
In my conversations with several folks on both sides of the issue during
Montreal meetings, I've come to the conclusion that the root reasons to
either a 10 or 9.584640 Gbps are purely ease-of implementation based and
5) Consider a Ethernet to OC-192 line card (feeding a fiber or wavelength)
operation. Assume that receive and transmit paths are separate on the
and related (i.e. full duplex) on the Ethernet side:
a) Ethernet -> SONET @ 9.584640 Gbps: The Ethernet side can continuously
the SONET link with no flow control required.
b) Ethernet -> SONET @ 10 Gbps: The Ethernet side must be flow
prevent over-feeding the SONET link
c) SONET -> Ethernet @ 9.584640 or 10 Gbps: The Ethernet side can
source SONET data but will flow control or drop packets downstream
network is congested.
> Given a raw continuous bit stream at the PMD, some scheme for
> framing packets would be needed. 10M used a carrier, 100M used
> 1000M used coding. Using coding where the PMD speed is fixed at
> would mean a further speed reduction (probably 10-20%) at the
> interface. The discussion at the meeting has already started to
> reducing the useful throughput at the MAC/PLS below the data
> alternative framing scheme presented to HSSG, which has a smaller
> reduction, requires a packet length header -- a departure from
Richard Taborek Sr. Tel: 650 210 8800 x101 or 408 370 9233
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