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Re: Issues concerning 10GbE speed standards


I don't know if you realize it or not, but you just gave a very good reason for
not implementing 8B/10B coding for a serial MAN/WAN PHY.  With fewer wavelengths
available over WDM systems, it makes MAN/WAN implementation costs higher per user
for given high bandwidths.  That economic issue makes the minor difference
between 8B10B  and scramble code electronics insignificant.

Roy Bynum,

Drew Perkins wrote:

> Peter and Roy,
>         The cost of higher speed in the WAN is not so much that of the
> electronic parts, but rather the fact that you need more of them for long
> distances. This is because most optical effects such as dispersion increase
> with the square of the distance. Thus increasing the speed by 25% increases
> the optical effects by 56%, and that tends to decrease the distance you can
> go by  about a third. Then you need 33% more spans to go the same distance.
> Also, in order to send 25% more bits, you wind up increasing the power by
> 25%, and you use more optical bandwidth. And since you are sending more
> bits, you are using more optical bandwidth. These facts result in fewer
> optical channels being supportable on a fiber, resulting in more fibers
> being used, resulting in more line systems, etc.  The result again is more
> equipment and higher costs.
> Actually, the electronic parts might become less expensive with the 25%
> extra speed. The balanced nature of the 8B10B code decreases the cost and
> attention that must be paid to jitter.
> Drew
> ---------------------------------------------------------
> Ciena Corporation                 Email: ddp@xxxxxxxxxxxx
> Core Switching Division                 Tel: 408-865-6202
> 10201 Bubb Road                         Fax: 408-865-6291
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> -----Original Message-----
> From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of
> Peter_Wang@xxxxxxxx
> Sent: Friday, June 25, 1999 8:35 PM
> To: rabynum@xxxxxxxxxxx
> Cc: stds-802-3-hssg@xxxxxxxx
> Subject: Re: Issues concerning 10GbE speed standards
> Roy,
> >From a number of the component vendors' presentations at CFI, I don't recall
> anyone claiming that the cost of the electronic parts (SiGe or GaAs) will be
> much different between 10 & 12.5 Gbps.  The primary cost issue seemed that
> of
> the relative laser performance (e.g. temperature stablization).  Also, if
> you
> are talking about "converting" an existing Sonet chip to silicon (meaning
> that
> the existing desing is in GaAs) and throwing away a bunch of circuits, I
> wouldn't be so sure that the development cost would be much less.  In any
> case,
> assuming the volume is large (which I'm sure everyone's hoping), the
> development
> cost will be amortized, and hence not a significant factor.  But this is a
> discussion for LAN (or enterprise) applications.  I was trying to understand
> the
> economics of applying Ethernet to WAN but forcing it within the existing WAN
> practice, and hoping you could provide some insight.
> Peter
> Roy Bynum <rabynum@xxxxxxxxxxx> on 06/25/99 04:50:23 PM
> Please respond to rabynum@xxxxxxxxxxx
> Sent by:  Roy Bynum <rabynum@xxxxxxxxxxx>
> To:   Peter Wang/HQ/3Com
> cc:   stds-802-3-hssg@xxxxxxxx
> Subject:  Re: Issues concerning 10GbE speed standards
> Peter,
> Just because a SONET OC192C framing is used, does not mean that the OAMP
> functionality is active in the LAN interface.  If OAMP processing is not
> needed, only the existing SONET chip set, converted to silicon, with
> most active functionality, other than path BER can be disabled.  This
> will leverage the existing technology without the higher cost of the
> APS, line and section overhead, etc.
> Having worked on devices before, I know that the higher the bit signal
> rate the more expensive the devices.  With a PHY that is 1/4 higher in
> bit rate, compared the 8B/10B signal rate, the OC192 rate may be less
> expensive.
> Roy
> Peter_Wang@xxxxxxxx wrote:
> >
> > It will help a great deal if you could point out specific aspects and
> approaches
> > where an Ethernet extended to support all of the existing common carrier
> O&M
> > requirements, encapsulated within the existing Sonet/SDH structure,
> running
> over
> > existing OC192/STM64 facilities, will actually come out costing
> significantly
> > less that the current solution?
> > - Peter
> >
> > Roy Bynum <rabynum@xxxxxxxxxxx> on 06/20/99 07:34:08 AM
> >
> > Please respond to rabynum@xxxxxxxxxxx
> >
> > Sent by:  Roy Bynum <rabynum@xxxxxxxxxxx>
> >
> > To:   wthirion@xxxxxxxxxx
> > cc:   stds-802-3-hssg@xxxxxxxx, stds-802-3-hssg-speed@xxxxxxxx (Peter
> >       Wang/HQ/3Com)
> > Subject:  Issues concerning 10GbE speed standards
> >
> > Walt, et al,
> >
> > The issue of speed is one of economics.  The existing GbE standard does
> > not allow for any operations support for the optical fiber facility.
> > This makes GbE very expensive to maintain and support over a MAN/WAN
> > environment.  The cost of ownership of GbE will prevent it from having a
> > masive impact directly on the cost of MAN and WAN data communications.
> >
> > Common carrier protocols, such as DS1/DS3/SONET/SDH have operations and
> > maintencance functionality incorporated in the overhead of the
> > protocol.  DS1 and DS3 have a subcarrier that provides remote and
> > reverse signalling outside of the transport "payload".  This allows
> > carriers to troubleshoot and maintain remote systems without haveing to
> > dispatch someone for every little issue.  In some respects, GbE fails to
> > meet the 802.3 functional requirements for interoperation with common
> > carrier systems.
> >
> > 1000BaseSX and 1000BaseLX are optical networking standards.  Whether
> > this was the intention or even the perception of the 802.3 working
> > group.  The working group did not include any support for operations or
> > maintenance in the optical domain for this protocol.  The functional
> > operations of copper LAN facilities are well understood by the 802.3
> > working group, but when you get beyond multi-mode, 850nm, optical
> > transport, it is no longer a LAN, it is a WAN.  Some will say that 30km
> > is a MAN, not a WAN.  If you apply the same function processes
> > distictions to optical systems that are applied to copper systems, you
> > will discover that a MAN is actually a WAN within a single central
> > office domain. When I was actively working on Ethernet, when it left the
> > building, it was no longer a LAN, it was a WAN.
> >
> > In order for 10000BaseX to support MAN/WAN systems within common carrier
> > facilities, common carrier operations and maintance support must be
> > within the protocol.  SONET/SDH are the current, and most widely
> > deployed transport protocols within the common carrier domain.
> > SONET/SDH use the transport overhead to provide that functionality.
> > That functionality allows the common carriers to reduce the operations
> > and support costs for the fiber optic transport systems, and thus lower
> > the overall costs passed on to the end users.  This will be the economic
> > breaking point for 10GbE.  Can it directly support the fiber optic
> > transmission system?  Is there any reason why it should not be able to
> > directly provide operations support for the optical fiber systems?
> >
> > A second economic issue of speed for 10GbE is one of utilizing existing
> > technology and standards at the ~10Gigabit speed range.  A masive
> > install base of facilities and support already exist for OC192/STM64 on
> > a global scale.  Optical amplifers, signal and clock recovery
> > regenerators, and other systems are already in place to carry
> > OC192/STM64 signals in metropolitan as well as wide are networks.  I
> > would not want to contemplate the economic impact of having to install
> > totally seperate technology to support 10GbE.  If it can not use the
> > existing ~10Gb technology and facilities, Other than "dark fiber", 10GbE
> > will have to be installed over a totaly new, and totaly seperate
> > facilities.  Is there any reason why 10GbE should not support and make
> > use of the existing ~10Gb transport facilities?
> >
> > I hope that this message has not been too long.  As an employee of a
> > common carrier company, I have a recognizable vested interest in looking
> > toward 10GbE as a major economical alternative to existing data tranport
> > technolgy, such as TDM or ATM.  I have almost 20 years of designing,
> > installing, and supporting LAN, MAN, and WAN systems.  I have seen the
> > economics change as more self-supporting protocols and technologies have
> > become available.  The key is to provide a protocol that allows remote
> > operations support, which reduces the number of "warm bodies" that are
> > required to support the systems.  This is what I am asking for.  Is
> > there any reason why this can not be done?
> >
> >                          Thank you,
> >                          Roy Bynum
> >                          MCI WorldCom