RE: Why an optical PHY makes 10GbE a non-LAN protocol

[Fred Weniger <weniger@xxxxxxxxxxx>]

Drew,

I am not familiar with the acronyms "UPSR" and "BLSR".  Could you please
define these?  Thank you?


At 09:02 PM 6/27/99 -0700, Drew Perkins wrote:
>
>Roy,
>	I believe that the difference between LAN and WAN (including MAN)
>protocols has been mentioned in another very recent note. The key difference
>is whether or not it is the same administration that owns and operates both
>ends of the communication as well as the media in between. This is typically
>the case with LANs. WANs, on the other hand, are typically owned, operated,
>and managed by a service provider. Because the service provider needs to
>have good tools to know when they are not providing good service, and to
>locate the problem causing bad service, and to restore service while there
>is a problem, WAN protocols tend to have facilities to provide superior
>OAM&P compared with LAN protocols. Flavors of Ethernet do not currently have
>the mechanisms for providing these tools.
>
>There may also be significant differences between MAN and WAN protocols. In
>both the SONET/SDH worlds and DWDM worlds, the protocols used over MANs and
>WANs may differ significantly. MAN protocols are often built to favor
>simplicity and performance over efficiency. Hence the use of UPSRs. WAN
>protocols are more often built to favor efficiency over simplicity and
>performance due to the significantly higher costs. Hence the use of 4 Fiber
>BLSR.
>
>Drew
>---------------------------------------------------------
>Ciena Corporation                 Email: ddp@xxxxxxxxxxxx
>Core Switching Division                 Tel: 408-865-6202
>10201 Bubb Road                         Fax: 408-865-6291
>Cupertino, CA 95014              Cell/Pager: 408-829-8298
>
>
>-----Original Message-----
>From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
>[mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of Roy Bynum
>Sent: Sunday, June 27, 1999 6:15 AM
>To: Peter_Wang@xxxxxxxx
>Cc: stds-802-3-hssg@xxxxxxxx
>Subject: Why an optical PHY makes 10GbE a non-LAN protocol
>
>
>
>Peter,
>
>I have been trying to figure out what the distinction between a LAN protocol
>and
>others.  There was the "assumption" made with the development of 1000BaseLX
>that the
>moderate power and 13xx wavelength specification would made it a MAN
>protocol. It
>did not, it only opened the door for it to no longer be a LAN only protocol.
>In
>optical networking with optical PHYs, there is no such thing as a distiction
>between
>a MAN and a WAN protocol, only between LAN and non-LAN protocols.
>
>In re-thinking the distiction between the protocols that are restricted to
>short
>distances, and those that are not, I may have found the answer.  Direct
>responce
>protocols, such as ESCON have a specific acknowledge responce time on each
>data
>block.  The transaction concurrency responce time of ESCON resticts it to a
>limited
>distance.  The IBM standard has some specific distance limitations to it.
>That
>specific distance limitation, based in data block acknowledge responce time,
>limits
>ESCON to being a LAN standard.  Changing the PHY by making it optical with
>high
>launch power will not make into a WAN protocol, because the limitation is
>not in the
>PHY, it is in the protocol itself.
>
>Because of the latencies involved with the slow responce time of end systems
>and
>mulitiple segments linked with repeaters, the original 802.3 did not have
>restrictive frame acknowledge responce times.  At the time, 802.3 was
>distance
>limited by the distances of coax cable. When full duplex 10BaseT came into
>being,
>802.3 became a point to point protocol, not much different from any other
>point to
>point protocol.  Some vendors even developed optical conversion and bridge
>interfaces that were optical.
>
>When 802.3 was increased to full duplex 100 mb speeds and given an optical
>PHY, the
>distance limitations were offically removed.  Full duplex 100BaseSX is a
>non-LAN,
>point to point protocol.  Some people even implemented 100BaseSX as in a MAN
>configuration using optical wavelength converters.  Only economics and
>access to
>long distance fiber prevented 100BaseSX from becoming a WAN protocol at the
>very
>first.  Full Duplex 1000BaseLX offically gave sanction to non-LAN 802.3.
>With
>optical wavelength converters, even 1000BaseSX does not have any LAN
>distance
>limitations.  Only the "assumption" that 802.3 was a LAN protocol did not
>allow the
>802.3 WG to reconize that they were creating a non-LAN standard.
>
>The lack of restrictive frame acknowledge responce timers will also make
>serial
>optical 10GbE a non-LAN protocol by default.  Optical amplifiers will allow
>implementations of 10GbE that will go at least 600km.  In the optical
>networking
>environment there is no difference between a MAN or WAN at the protocol
>level.
>Because of physical installation limitations, multi-fiber, parallel, MMF,
>10GbE may
>be a LAN only implementation.  In spite of the "assumption" that 802.3 is a
>LAN
>protocol, serial optical 10GbE will not be.  Serial optical 10GbE will be a
>MAN/WAN
>protcol.
>
>Thank you,
>Roy Bynum,
>Optical and Data Network Technology Development
>MCI WorldCom
>
>>
>


Fred Weniger
Product Marketing Manager, Gigabit Products
Vitesse Semiconductor Corporation
741 Calle Plano, Camarillo, CA 93012
Phone: 805-388-7571   Fax: 805-987-5896
E-mail: weniger@xxxxxxxxxxx