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

[Rich Taborek <rtaborek@xxxxxxxxxxxxxxxx>]

Drew,

I agree with your point of view about the differences between MAN/WAN and the
other AN's. That's why I never took issue with it.

I'll gladly withdraw extended LAN since, hopefully, I've made the case for
1000BASE-LX being a LAN PHY. BTW, SAN stands for either Storage or System Area
Network, the latter referring to the clustering of processors. If I have to
digest all your WAN terms, I'm not above throwing some storage, channel, and
processor terms your way ;-)

I also agree that no flavor of Ethernet "has the tools that many service
providers want in order to provide an easily-managed, robust communications
service." To the best of my knowledge and relatively short relationship with
802.3, I don't know of any Calls for Interest to add such tools In addition, I
am not aware of any proposals within the HSSG to add such tools. However, I'm
sure that you would get strong interest from many members if such a call were
made and I believe that Ethernet's architecture is flexible enough to
incoprorate the functions required to implement these tools.

Best Regards,
Rich

--

"Perkins, Drew" wrote:

> I think that we need new terms. I don't know what they should be, but
> LAN/WAN/MAN/SAN/xAN are too overloaded. The critical difference between LAN
> and WAN has never been just the distance between two communicating
> endpoints. As I said previously, I believe the critical differentiator is
> whether or not the protocol has tools to allow a 3rd party service provider
> provide a managed L1 transmission service between two points.
>
> Even if Gigabit Ethernet is being used over private fiber end-to-end across
> Canada, that doesn't mean that it has the tools that many service providers
> want in order to provide an easily-managed, robust communications service.
>
> 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 Rich
> Taborek
> Sent: Tuesday, June 29, 1999 3:32 PM
> To: rabynum@xxxxxxxxxxx; HSSG
> Subject: Re: Why an optical PHY makes 10GbE a non-LAN protocol
>
> Roy,
>
> I know that you have made several arguments to the point that Gigabit
> Ethernet is
> not a LAN because of its 1000BASE-LX variant which supports extended
> distances. I'd
> like to respond with some relevant history which I am personally familiar
> with:
>
> Way back in 1988 or so (+ or - one year) I was working at IBM designing
> mainframe
> channels. One of the neatest products I've had the opportunity to work with
> at the
> time was a 3044 Channel Extender. This product consisted of two physical
> boxes, one
> connected to the Bus and Tag cables of a mainframe channel interface, the
> other
> connected to the Bus and Tag cables of the first in a series of peripheral
> devices,
> other devices being daisy chained to the first device. A fiber optic cable
> connected
> the two 2 3044 units. In this fashion the existing 120 meter Bus and Tag
> cable limit
> could be extended to 2 km over 62.5 um MMF and 3 km over 50 um MMF. The line
> rate
> was 200 Mbps, the encoding was 8B/10B, and the transmitter was an LED. The
> 3044 was
> an excellent technology evaluator for IBM's current fiber optic-based
> mainframe
> channels dubbed ESCON (TM). ESCON channels, first introduced in 1990 and the
> current
> workhorse, use the same basic PHY but different framing than the 3044
> channel
> extended. One other significant addition is that ESCON channels also
> supported a
> laser-based PHY variant, extending the supported ESCON distance to 20 km
> with a 1300
> nm laser source. Up to three links could be arranged in line through two
> switches,
> forming a 60 km link between mainframe channel to peripheral.
>
> Other LAN protocols like FDDI supported similar extended LAN distances.
> Fibre
> Channel broke the 1 Gbps barrier with a completed standard in 1994,
> supporting
> distances of up to 10 km in ANSI X3.230-1994 (FC-PH). The GbE 1000BASE-X PHY
> is
> based upon the FC-PH PHY.
>
> The point in all the prior rambling is the GbE was not the first to venture
> into the
> extended LAN (call it MAN or WAN, whatever) space. Other proprietary or
> standard
> solutions may have gotten there earlier than even the 3044. I'm sure that
> the IEEE
> 802.3 has no shortage of communications systems historians.
>
> Existing LAN and SAN data communications protocols including Ethernet, FC,
> HIPPI,
> FDDI have done more than extremely well at meeting the needs of the
> environments for
> which they were designed from a cost, functionality, reliability,
> manageability,
> operations, serviceability, configuration flexibility, salability (I could
> go on and
> on) point of view. The WAN marketplace, and perhaps the MAN marketplace as
> well, is
> new and unfamiliar territory to many from the LAN and SAN community.
>
> I don't find it altogether unreasonable, that given the proper requirements,
> guidelines, and historical perspective, that 10 Gigabit Ethernet can
> assemble a
> standard that addresses all LAN and extended LAN environments as did its
> predecessors as well as venturing into the MAN and WAN space while
> simultaneously
> providing compatibility with all of the existing MAN and WAN infrastructure.
>
> What's wrong with the above picture?
>
> --
>
> Roy Bynum wrote:
>
> > ... (text deleted)
>
> > 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@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
> > >
> > > >

-------------------------------------------------------------
Richard Taborek Sr.    Tel: 650 210 8800 x101 or 408 370 9233
Principal Architect         Fax: 650 940 1898 or 408 374 3645
Transcendata, Inc.           Email: rtaborek@xxxxxxxxxxxxxxxx
1029 Corporation Way              http://www.transcendata.com
Palo Alto, CA 94303-4305    Alt email: rtaborek@xxxxxxxxxxxxx