Assumptions

[pbottorf@xxxxxxxxxxxxxxxxxx (Paul Bottorff)]

Walter:

Certainly traditional Ethernet has used 10X speed increases on a base 10.0
clock speed. In the early days of Ethernet there was no compelling reason
to use any other speed since the network was clearly limited in extent by
CSMA/CD.

The issue of speed in MAN and WAN applications is an issue of
interoperation with SONET networks and with pure DWDM Optical networks. The
issue of interoperation with SONET is not a telco issue. The IETF's PoS
systems is based on using a SONET rate. The OIF is working on a data link
for the MAN based on SONET rates. These groups are certainly not telco
groups. In the wide area SONET is a major part of the installed base.
Matching the SONET data rate allows leveraging the existing installed base.
Photonic networks of today are built using SONET optical components and
system engineering. Though future Photonic DWDM networks could adapt to a
different data rate, they also must support SONET, therefore the most
desirable system is one where the data rate of 10 GigE and matches OC-192
allowing both to be carried over a data independent DWDM Optical Network.

If the data rates are not matched it will be impossible to carry 10 GigE
over a single OC-192 wavelength. Without the ability to migrate the
installed base the MAN and WAN will be compelled to use other technologies
then 10 GigE as a general data transport.

I guess we can get by with two speeds for 10 GigE one for LAN applications
and one for MAN applications. 

Paul

> Ok, let's see if we can get the discussion started.
> 
> My take from the interim is that the major discussion point is whether
> the speed should be ~10 Gb/s or exactly 10 Gb/s. Ethernet has
> traditionally moved in orders of magnitude, 10 Mb/s, 100 Mb/s, 1000
> Mb/s. This speed is measured at the MAC. The physical layer was free
> to to whatever necessary. For example, 1000Base-X provided 1000 Mb/s
> at the MAC, but was 1250 Mb/s on the physical medium due to 8B/10B
> encoding.
> 
> My impression is the long haul telco camp wants the speed to match the
> speeds currently being used for Sonet, etc. The assumption is that it
> will be easier to interconnect ethernet networks with the WAN if the
> speeds are the same.
> 
> Is this the correct starting point?
> 
> Walter Thirion
> Vice President, Strategic Technology Development
> Level One Communications
> 512-407-2110
> 
> 
Paul A. Bottorff, Director Switching Architecture
Bay Architecture Laboratory
Nortel Networks, Inc.
4401 Great America Parkway
Santa Clara, CA 95052-8185
Tel: 408 495 3365 Fax: 408 495 1299 ESN: 265 3365
email: pbottorf@xxxxxxxxxxxxxxxxxx