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

[Roy Bynum <rabynum@airmail.net>]

Drew,

Now we are getting to the crux of the problem.  802.3 has its own L1
definitions.  Most other L2 extended distance protocols do not.  By adding
extended distances private systems and commercial service providers can now
utilize Native data over long haul networks.

This year, full duplex GbE is being deployed from one side of Canada to the
other using private fiber.  Because it is using private fiber, does that make
this implementation a MAN?  Early next year, if plans continue, there will be a
metro deployment of full duplex GbE mapped into SONET.  Does that make this
deployment a MAN?

Which is a MAN and which is a WAN?  What is the difference at L2?  What kind of
difference does one distance factor make over the other?  Does stripping the L1
PHY from 802.3 and mapping it into another PHY change it from a LAN to a WAN
protocol?  If so, what about going from half duplex to full duplex?  Does
multi-plexing 802.3 with other data channels over a common PHY make it into a
WAN implementation?  Would defining a single channel, non-multiplexed long haul
PHY for 802.3 make it a WAN or a MAN or a LAN protocol?  Would it make any
difference L2?

I am not trying to be difficult here.  I am trying to break down the prejudged
view point that 802.3 is, has always been, and will continue to be nothing but a
LAN protocol.  The operational simplicity, auto configuration functionality,
high market penetration, and other factors makes 802.3 the default Native data
protocol all over the world.  There is no way that it could be constrained to
specific implementations.

802.3 does not have to automatically implement the operational complexity of
common carrier optical systems in order to support a PHY that can be used by
optical common carrier systems.  The complexity of the operational support is an
implementation issue.  Sometimes trying to provide the same level of operational
support for an L1 protocol that does not have the capability can become even
more complex and expensive.  This would tend to limit the market penetration of
10GbE.  The lessons learned by the common carrier industry with long haul
systems can be a resource to improving the extended distance capabilities of
10GbE.  What would benefit from allowing a prejudged view point to prevent
leveraging existing technology?


Thank you,
Roy Bynum,
MCI WorldCom



"Perkins, Drew" wrote:

> No, what I'm talking about are market requirements differences, particularly
> for L1 protocols. Making 802.3 full-duplex did not turn it into a WAN
> protocol, it was only an enabling factor that allows it to work over long
> distances. Many other things are required to meet the requirements of WAN
> service providers.
>
> Drew
> ---------------------------------------------------------
> Ciena Corporation                 Email: ddp@lightera.com
> 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@majordomo.ieee.org
> [mailto:owner-stds-802-3-hssg@majordomo.ieee.org]On Behalf Of Roy Bynum
> Sent: Monday, June 28, 1999 8:09 PM
> To: Perkins, Drew
> Cc: 'stds-802-3-hssg@ieee.org'
> Subject: Re: Why an optical PHY makes 10GbE a non-LAN protocol
>
> Drew,
>
> What you are talking about are implementation differences, not L2 protocol
> differences.  L2 protocols such as SDLC, PPP, etc., all have fairly long
> acknowledge responce timers.  Closed loop protocols such as FDDI are less
> forgiving, just as half duplex 802.3 was less forgiving.  Full duplex 802.3
> acts
> more like PPP in the regard of supportable link distance.
>
> I have seen SDLC implemented over LAN facilities such as Token Ring.  It
> worked
> just fine.  Does that make SDLC into a LAN protocol?  SDLC was often used as
> the
> WAN protocol for Token Ring source route bridging.  Does that make SDLC a
> WAN
> protocol?  These are implemenation issues.  What is it that makes SDLC a LAN
> or
> a WAN protocol?  A WAN protocol has the ablity to work over extended
> distances;
> a LAN protocol does not.  Does full duplex 802.3 have the ability to work
> over
> extended distances?
>
> This is a door that has already been opened.  802.3 was altered into an
> extended
> distance, WAN, protocol by making it full duplex.  It may not have been the
> intention of the 802.3 WG to do so, but that is what was accomplished.
> Adding
> an extended distance PHY sanctioned 802.3 for use over extended distances,
> either over privately owned facilities, or over commercial services
> facilities.
>
> I simply want to point out that what was accomplished by the 802.3 WG was
> greater than what they intended.  They opened the extended distance, WAN,
> market
> place to Native data, 802.3.  This is going to have more of a major impact
> on
> long haul data communications that it will have on the LAN environment,
> which
> already has Native data, 802.3.  The over all long term result will be lower
> cost data communications over extended distances, WANs as well as LANs.
>
> Thank you 802.3 WG,
> Roy Bynum,
> MCI WorldCom
>
> 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@lightera.com
> > 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@majordomo.ieee.org
> > [mailto:owner-stds-802-3-hssg@majordomo.ieee.org]On Behalf Of Roy Bynum
> > Sent: Sunday, June 27, 1999 6:15 AM
> > To: Peter_Wang@3com.com
> > Cc: stds-802-3-hssg@ieee.org
> > 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
> >
> > >