Re: [HSSG] Reach Objectives
Just a brief comment or two on the latency subject touched on in this
email. First, when you are talking about ULH distances, you are talking
about propagation delays in the milliseconds. Packetization delays in
the low microseconds or below lose most of their significance.
Furthermore, these systems all run over high gain FEC. High gain FEC has
it's own decoding, and sometimes encoding, latencies that are typically
measured at least in microseconds and often in tens to hundreds of
microseconds depending on the code used. Again, worrying about
cut-through processing rather than store-and-forward delays does not
have a particularly high ROI.
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: Geoff Thompson [mailto:gthompso@xxxxxxxxxx]
Sent: Tuesday, August 22, 2006 11:31 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] Reach Objectives
Aaron-
My personal opinion (which may or may not correlate to the opinion of my
employer) is that ultra long haul (ULH) will come into the conversation
in
due course. I don't think it is necessary up front.
Some of the requirements are likely to be taken up by existing optical
amplifiers and maybe even existing 3R repeaters (less likely).
If a new regenrative repeater is considered to be necessary to extend
the
reach of what we have for shorter haul, then it is a nice small project
that we can do separately (and perhaps a little later). Such a repeater
was
implicitly inferred by Joel and Steve and explicitly by me during the
earlier discussion of regenerative link terminations with lower latency
than you might be able to get with full decoding.
(See my message: Tue, 15 Aug 2006 13:12:54 -0700, Re: [HSSG] HSSG MAC &
PHY
Options )
Since I think that is a reasonable straightforward extension of what (I
expect) we are going to do anyway, I don't think we have to make life
more
complicated by including it now.
In the meantime, we can concentrate our discussions on reach objectives
for
a single link (although my opinion is that we shouldn't do anything
radical
in the long haul area).
Geoff Thompson
At 09:49 AM 8/22/2006 , Aaron Dudek wrote:
>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]
>> 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
>>
>>
>>
>> _____________________________
>>
>>
>>______________________________________________________________________
____
>>__________________________________________________________
>> From: John DAmbrosia [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
>>
>>