Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: Distance Motion

HSSG Distance Friends:

Such a interesting discussion, I just could not resist to jump in to join
the crowd.  

I believe our objective is to determine the distance specification for 10GbE
which basically is LAN.  As in many LAN standard generations (Ethernet,
FDDI, ATM, Token Ring,..), and even Fibre Channel, the distance issue has
been determined based on the Cost-Performance, the Market Needs, but not
types of "Components".  I just wonder why type-of-component became the main
focus for our distance selections.  Furthermore, why we should be
responsible for LAN, MAN and WAN definitions, considering our task is to
provide 10GbE users the capability of operating distances using any
technology of the most cost-effectiveness.  

Just to make sure I have the correct understanding of technical terms, I
reviewed several Telecom, Datacom, Communication...etc. Standard Reference
publications in library about the definition of LAN, MAN, and WAN.  None of
them define LAN, MAN, and WAN based on the component types.  The only clear
statement common to different reference books is "WAN typically connects
many LAN clusters, and WAN is subject to public telecommunications
regulation", but not LAN.  MAN definition is so vague, which can have both
of them as long as it is in the middle. 

I am involved, and make technical decisions for Unisys world wide optical
communications, which are LANs basically.  We have inquiries from users all
over the world to extend distance beyond their present installations ranging
100 meter to over 50 km.  The only thing market cares is performance and
cost, but not technologies or types of components.  By the way, SONET uses
LED and MM fibers for interoffice connections for very low data rate. 

From LAN/WAN-Standards and Market-needs point of view, there are no
regulations that constraint us from making DISTANCE decisions.  I believe
the only rule we have is our obligation to users, to marketplace to provide
the most cost-effective distances for 10GbE. 

Ed Chang
Unisys Corporation


-----Original Message-----
From: Roy Bynum [mailto:RBYNUM/0004245935@xxxxxxxxxxx]
Sent: Thursday, June 24, 1999 6:09 PM
To: Thomas Dineen; HSSG Distance
Subject: Distance Motion

Thomas, et al,

I am in favor of having a LAN only distance definition, motion item

Because of optical networking issues, such as optical amplifiers, OEO
transducers, DWDM, etc., I can not seperate the MAN (10000BaseLX)
interface from a WAN (10000BaseLX) interface. In spite of an attempt
to create a language that appears to limit the distance to MAN
applications, exiting 1000BaseLX is being deployed as a WAN interface.
In optical transmission interfaces, there is not a distinction between
MAN and WAN. They use the same wavelength; they use the same output
power; they use the same framing and link protocol; they use the same
single mode fiber; they use the same physical interface. Look at what
Bill St. Arnaud is doing at CANARIE. I can not agree to the motion to
seperate the MAN from the WAN, items 2 and 3.

The issue of fiber type and distance are specifically linked. Any
interface that uses multi-mode fiber (MMF) is limited to LAN systems.
Any interface that uses single-mode fiber (SMF) can be used in MAN/WAN
systems in addition to LAN systems. In MAN/WAN systems, wavelengths
can be either in the S band, C band, or the L band. All three use SMF.
All three have been used for interfaces in both MAN and WAN systems.
The difference that I see between LAN and MAN/WAN interfaces is the
fiber type.

Roy Bynum
Optical and Data Network Technology Development,
MCI WorldCom
(972) 729-7249