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I agree that there are a lot of other things that can impact the cost other than silicon gate count. If all other components of the two systems were equal, the WAN would still cost more (in silicon or in processing cycles) than the LAN due to the requirements to process the overhead.
From: Rich Taborek [SMTP:rtaborek@xxxxxxxxxxxxxxxx]
Sent: Monday, September 06, 1999 1:12 PM
Subject: Re: Long distance links
That's (cost) a dangerous pedestal to get on. The cost of a multi-gigabit PHY is primarily governed by its opto-electronics and associated high-speed and Tx/Rx electronics such as the Tx Laser Driver and Rx Photo Diode Pre-Amplifier, Trans-Impendence Amplifier, Post Amplifier, whichever are applicable times their quantities and in consideration of the level of integration.
At multi-gigabit rates, the connection between Tx/Rx opto-electronics and associated Tx/Rx electronics are critical and packaging gets expensive depending on the architecture of the PHY.
I believe that, in general, silicon gate count for any multi-gigabit PHY gets lost in the noise.
My argument is that the architecture of the SONET OC-192 WAN PHY is far from the cheapest possible for 10 GbE based on its requirements for the highest speed opto-electronics and associated high-speed and Tx/Rx electronics. I don't want to see all 10 GbE connections encumbered with this unnecessary cost.
"Booth, Brad" wrote:
I'd like to address the cost issue. In a silicon gate count, the MAC for a WAN or a LAN should be the same cost. As for the PHY, a WAN PHY is going to be more costly than a LAN PHY if you look at the silicon gate count. The reason for the WAN PHY being more expensive is that the PHY is not only an encoder, it is also a framer. Where a LAN PHY would perform encoding/decoding and translation from serial-parallel, the WAN PHY must perform all that plus add overhead and perform framing, which adds complexity and cost.
I feel that a WAN PHY and a LAN PHY are required so that LAN implementations are not burdened with the added cost and complexity of overhead and framing that are required to utilize the installed WAN OC-192 base.
Austin Design Center
Intel Network Interface Division
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I have seen and heard a lot of issue about the WAN compatible MAC/PHY being more
expensive than a LAN only MAC/PHY. Has anyone done any actual cost analysis?
Having done development work before, even if it was some time ago, the ability to
use existing technology and chips was always less expensive for initial
deployment. A lower frequency signal encode and decode was always less expensive
over the long term. Semi-static information processing was always less expensive
was less expensive than active information processing. Unless it is legacy WAN
vendors trying to protect their control and high profit margins for WAN
interfaces, I can not see why a WAN compatible PHY should be more expensive than a
LAN only PHY at the same laser powers. I have seen nothing to support it that
assumption. As a customer, I would like to see the WAN comparable costs to the
LAN interfaces. As a customer, I would like to be able to take the same type of
interface and use it where ever my implementation architecture requires. As a
customer I would like to be able to have unmodified 802.3 frames delivered from
any one place to any other place with the least expense, in both equipment and