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Re: [HSSG] Reach Objectives



Drew,
I think you are touching on some important points here where we need to be VERY careful.
 
I think that many will agree that a key mistake of 10G was to develop a LAN PHY and a WAN PHY that operated at a different payload bitrate. The WAN PHY was important because, as has been discussed, 10G was where we really got into having Ethernet as an Infrastructure interface, so it needed to work seamlessly into transport networks. But we should have selected a bitrate that works into all transport hierarchies.
 
As far as compatibility with transport technologies, a few thoughts:
- If we are considering multiple lane approaches and have the idea to carry the lanes individually across a transport network, it is essential to consider the technologies used in those transport networks. For example, if we are considering lanes on the order of 10G in size, we should surely select an exact rate that fits into an STM-64/OC-192 or G.709 OPU2 payload. If we also want to carry such a lane over a 10G LAN PHY, we should limit the data rate used over that iterface so that it still fits into the transport network.
- Regarding differential delay or skew, it depends on the underlying transport technology and the network span before reaggregating. With SONET/SDH, you are dealing with a basic frame rate of 125 microseconds, so virtual concatenation in this environment needs to consider several frames worth of differential delay. With G.709, however, the framing is essentially to give you OAM, a multiplex structure, and FEC rather than being tied to the payload rate. At 10G, the G.709 frame is just over 12 microseconds, and at 40G it is just over 3 microseconds. So the differential delay required to be compensated for virtual concatenation in G.709 is only 125 microseconds.
 
You mention the over-clocking of G.709 to carry LAN PHY. While this appears in some networks for point to point, it is not according to the standard, does not work with all equipment or components, and is not networkable (for example, you can't multiplex these over-clocked signals into a standard G.709 OTU3 (40G) signal). There has been a lot of angst in standards discussions about how to limit the proliferation of these kinds of solutions and get back to a coherent network architecture Since we are starting out in HSSG with a "clean slate" to define a new interface and have the freedom to select:
- Rates that match for the networks we want to interwork with
- Payloads that fit into the containers we want to carry them
I think we should NOT look to some of these special case implementations for how to build a new interface, but to the standards for the technologies where interworking or transport is important.
 
Finally, when (not if) we get to looking at 100G serial, I think we should remember the pain of 10G LAN PHY/WAN PHY and avoid repeating that experience. The ideal situation is if we could agree on a data rate, frame format, etc. that meets everybody's needs (not to mention generating extra volume with common technology to bring costs down). I think that it would be a good idea to work with the ITU-T to see if we could define a common, sensible evolution that works for data and transport environments (of course the lines between these are becoming increasingly blurred). It certainly wouldn't hurt to be working with the G.709 guys in ITU-T Q.11/15, and the optical physical interface guys in ITU-T Q.6/15.
 
You may recall that Glenn Parsons had described the fact that IEEE is now a sector member of ITU-T, and that plans were underway to hold a joint workshop in Late May in Geneva, probably between an ITU-T hosted IEEE 802.1 and or 802.3 interim meeting and the ITU-T Study Group 15 meeting. This could be a good opportunity for some face-to-face work on these topics. We can certainly correspond via liaison statements earlier.
Regards,
Steve


From: Drew Perkins [mailto:dperkins@xxxxxxxxxxxx]
Sent: Wednesday, August 23, 2006 1:02 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Reach Objectives

Menachem,

 

I think we need to differentiate between what PMDs we specify and what other PMDs we enable. For instance, I don't think it is the IEEE's place to specify an ULH PMD in terms of the optical specifications. However, this could be one of the more important applications of a HS Ethernet. So I think it would be worthwhile for us to enable vendors to develop it in a straightforward fashion. Thus I think we should get into some of the details that you mention including:

1.    PHY layer – what degree of compatibility with LAN-PHY, WAN-PHY (SONET/SDH), and/or G.709 is desired?

2.    What amount of differential delay (skew) will be allowed? What will be mandated for all conformant implementation?

 

It is clearly desirable to maintain compatibility with today’s DWDM transponders. This is a specific goal of some carriers that are participating in this process. Carriers would love to have a PMD option that leverages the 10G LAN-PHY or WAN-PHY. Of course this will depend on the answers to these questions and other decisions we make.

 

Many (I believe most) DWDM systems on the market now support the LAN-PHY natively by simply speeding up the G.709 OUT to run at ~11Gb/s instead of 10.7Gb/s rather than by doing some sort of overhead compression into SONET/SDH or the G.709 digital wrapper.

 

Drew

_____________________________

 

Drew Perkins

Chief Technology Officer

Infinera Corporation

1322 Bordeaux Drive

Sunnyvale, CA  94089

 

Phone:  408-572-5308

Cell:       408-666-1686

Fax:        408-904-4644

Email:    dperkins@xxxxxxxxxxxx

WWW :  http://www.infinera.com

 

 

_____________________________

 

 

-----Original Message-----
From: Menachem Abraham [mailto:mabraham@xxxxxxxxxxxxxxxxxxxx]
Sent: Tuesday, August 22, 2006 5:00 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Reach Objectives

 

Geoff,

 

Thanks for your comments.

 

I also believe that our efforts should focus on distances no higher than 10's of Km (up to and including metro).

 

If we decide as a group that it is an objective to make it easy to hook into LH and ULH transport systems in the installed base, we will have to study a number of issues such as:

 

(A) should we pick a data rate that is matching SONET rates?

(B) should we design our 802.3 std so that it tolerates a much larger inter-lane differential delay than what would be expected in a metro application of the standard?

(C) should we assume we never go through existing LH transponders and just have to COEXIST on the same fiber, optical amplifiers, dispersion compensators located in the huts, optical mux demux at both ends etc.

Etc. In this case we would assume a new type of LH tranponder purpose built for HSSG applications.

If this is the case, SONET rate compatibility would not be important.

 

 

Today's 10G LH and ULH system run mostly at OC-192 rates plus FEC overhead. Chip vendors were creative and managed to find ways to build devices that pack into these solutions the full 10G LAN data rate even though OC-192 is less than 10G.

I think (but I may be wrong) that they use available bandwidth in the management bits available in Digital Wrapper or something like that.

Not clean but seems to work...

 

Cheers,

Menachem

Menachem Abraham

Columbus Advisors

 

 

 

-----Original Message-----

From: "Geoff Thompson" <gthompso@xxxxxxxxxx>

Date: Tue, 22 Aug 2006 16:09:11

To:mabraham@xxxxxxxxxxxxxxxxxxxx

Cc:STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx

Subject: Re: [HSSG] Reach Objectives

 

Menachem-

 

 Thanks for your much more specific answer to the question. I'm afraid that my earlier answer was handicapped by my ignorance of the specifics of that market.

 

 Based on what you said, I believe the questions for us to consider or not are:

 

a) Will we consider long haul solutions.

OR

b) Will we limit ourselves to metro solutions and "transport end" (i.e. stuff that hooks into the transport infrastructure) solutions.

Back in the old days of 10Gig we spent an awful lot of time discussing the need for the WAN PHY to address case "b)". I think most of us didn't get it then. I would hope that with a different cast of characters involved in the discussions that we (or at least I, for one) could come out with a clear rationale for what we choose.

 

 (Just FYI, I believe the crux of the issue came down to whether or not one could have a 2 port bridge, as opposed to an Optical-Electrical-Optical repeater in a Transport Chassis.)

 

 None the less, I believe that my proposed answer stands. We don't need to tackle this issue in the first set of objectives and projects.

 

 I do remain interested (old repeater hack that I am) in looking into an O-E-O repeater that does not necessarily come all the way back up to the level of reassembling the full packet.

 

 Geoff

 

 At 01:30 PM 8/22/2006 , Menachem Abraham wrote:

 All,

 

 If we decide to include in our reach objectives Long Haul (e.g. 1000 km with

 optical amps placed at 80 Km spacing) and Ultra Long Haul (e.g. 3000 Km with

 optical amps at 80 Km spacing, without Optical-Electrical-Optical

 regeneration), we need to keep in mind that modulation/encoding/FEC choices

 play an important role in how far we can go on an optical amplifier based

 line system. Such PMD designs may be too costly for our < 80Km

 applications/objectives so we may end up with more PMDs.

 

 While there are some examples of Routers / Switches which have LH or ULH

 optical interfaces built in, most systems use Routers / Switches with

 shorter reach interfaces connected to separate Transport Chassis that house

 proprietary LH or ULH solutions. As far as I know the LH and ULH world does

 not have interoperable standard solutions today in terms of the signaling on

 the fiber.

 

 My input for our activities in HSSG is to optimize for cost and not require

 that one of our PMDs be directly useable as part of a LH or ULH line system

 (unless that is doable without incremental cost).

 

 Having said that, I believe we should debate the need to address "ease of

 HSSG data transport" on top of existing and emerging LH and ULH transport

 systems. If this debate already happened as part of the 10G 802.3 standard

 development and the conclusions apply here, perhaps somebody can educate

 those of us who were not involved at that time.

 

 Thanks,

 Menachem

 

 

 -----Original Message-----

 From: Aaron Dudek [mailto:adudek@xxxxxxxxxx: <mailto:adudek@xxxxxxxxxx> ]

 Sent: Tuesday, August 22, 2006 12:50 PM

 To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx

 Subject: Re: [HSSG] Reach Objectives

 

 Geoff,

 Shouldn't the migration to ULH systems have any impact on the spacing

 and hence be taken into consideration? Or is that beyond the scope for

 now?

 

 Aaron Dudek

 (703) 689-6879

 Sprintlink Engineering

 adudek@xxxxxxxxxx

 

 

 On Tue, 22 Aug 2006, Geoff Thompson wrote:

 

 > Roger-

 >

 > At 03:47 AM 8/22/2006 , Roger Merel wrote:

 >

 >       Agree with Drew.  Have a few additional comments on other reachs:

 >

 >       For reach objectives, we should start with customer based needs (for

 broad market potential) and only amend if an

 >       obvious technical limitation with compelling economics can t readily

 meet the broad customer need.

 >

 >       Specifically:

 >

 >       - Long Reach probably should be set at 80km rather than 100km (as

 this is the common hut-to-hut amplifier spacing

 >       in telecom)

 >

 >       - While 50m does serve a useful portion of the market (smaller

 datacenters and/or the size of a large computer

 >       cluster), it is somewhat constraining as I ve been lead to

 understand that the reach needed in larger datacenters

 >       is continuing to out-grow the 100m meter definition but the 100m

 definition at least serves the customer well.

 >       Certainly 10G-BaseT worked awfully hard to get to 100m (for

 Datacenter interconnect).

 >

 >

 > I wouldn't attach a lot of creedence to the 10GBASE-T goal for 100 meters.

 It was, I believe, mainly driven by the

 > traditional distance in horizontal (i.e. wiring closet to desktop)

 distances rather than any thorough examination of data

 > center requirements.

 >

 > Geoff

 >

 >

 >       - For both in-building reaches (50m & 300m; or 100m & 300m), the

 bigger issue which affects the PMD is the loss

 >       budget arising from the number of patch panels.  The shorter /

 datacenter reach should include a budget for 1

 >       patch panel.  The longer / enterprise reach should include a budget

 for 2 patch panels (one in the datacenter and

 >       1 in the remote switch closet).

 >

 >

 >

 >

 >       From: Drew Perkins [mailto:dperkins@xxxxxxxxxxxx: <mailto:dperkins@xxxxxxxxxxxx> ]

 >       Sent: Tuesday, August 22, 2006 1:24 AM

 >       To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx

 >       Subject: Re: [HSSG] Reach Objectives

 >

 >

 >

 >       John,

 >

 >

 >

 >       I suggest dividing Metro into Metro Short Reach at 10 km (equivalent

 application to 10GBASE-LR) and Metro

 >       Intermediate Reach at 40 km (equivalent application to 10GBASE-ER).

 >

 >

 >

 >       Drew

 >

 >       _____________________________

 >

 >

 >

 >       Drew Perkins

 >

 >       Chief Technology Officer

 >

 >       Infinera Corporation

 >

 >       1322 Bordeaux Drive

 >

 >       Sunnyvale, CA  94089

 >

 >

 >

 >       Phone:  408-572-5308

 >

 >       Cell:       408-666-1686

 >

 >       Fax:        408-904-4644

 >

 >       Email:    dperkins@xxxxxxxxxxxx

 >

 >       WWW :  http://www.infinera.com: <http://www.infinera.com/>

 >

 >

 >

 >

 >

 >       _____________________________

 >

 >

 >

 >

 ____________________________________________________________________________

 ________________________________________________________

 >       From: John DAmbrosia [mailto:jdambrosia@xxxxxxxxxxxxxxxxxxx: <mailto:jdambrosia@xxxxxxxxxxxxxxxxxxx> ]

 >       Sent: Monday, August 21, 2006 9:38 PM

 >       To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx

 >       Subject: [HSSG] Reach Objectives

 >

 >

 >

 >       All,

 >

 >       We have had some conversation on the reflector regarding reach

 objectives.  Summarizing what has been discussed

 >       on the reflector I see the following

 >

 >

 >

 >       Reach Objectives

 >

 >       Long-Haul   --> 100+ km

 >

 >       Metro       --> 10+ km

 >

 >       Data Center --> 50m & 300m

 >

 >

 >

 >       Data Center Reach Segregation

 >

 >       Intra-rack

 >

 >       Inter-rack

 >

 >       Horizontal runs

 >

 >       Vertical risers

 >

 >

 >

 >       Use this data to identify a single low-cost solution that would

 address a couple of the reach objectives

 >

 >

 >

 >       Other Areas

 >

 >       During the course of the CFI there were individuals who wanted

 Backplane Applications kept in for consideration,

 >       but I have not heard any further input in this area.  Are there

 still individuals who wish to propose Backplane

 >       as an objective?

 >

 >

 >

 >       John

 >

 >

 >

 >

 >