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I look forward to hearing the presentations on this today’s SMF Ad Hoc call.
However, having previewed the presentations, I continue to be disappointed that we are still discussing reach as if that was the only important application parameter. For example, shen_01_0113_smf only discusses 2km as if that was sufficient to describe the application. There is no mention of loss budget. Further, by only focusing on reach, the presentation perpetuates the myth that somehow the 10km reach is a niche application, and that we have just discovered 2km as an overlooked sweet spot.
It is well understood that there are few datacenter reaches that are 10km. What is important about widely used 10km interfaces like 10GE-LR, 40GE-LR4, and 100GE-LR4 is their greater than 6dB loss budget. In most applications, the reach is much less than 10km, but the >6dB loss budget is fully utilized.
2km reach has been an important and wide spread application, with both ITU-T and IEEE standardizing on a minimum 4dB loss budget. This means that over the last decade, end users have become accustomed to interfaces labeled 2km supporting a 4dB loss budget, and designed their central offices and datacenters around this. It is not clear why we continue to reinvent the wheel and propose reducing the established 4dB loss budget by fractions of a dB, for example as in vlasov_01_0113_smf to 3.5dB. If we were to deploy such an interface, it will cause problems in existing applications which try to use the new interface and find the supported loss budget less than expected. The new interface will require datacenter link engineering, as opposed to the plug-and-play paradigm that has made Ethernet so successful.
When discussing datacenter interfaces, it will be very helpful to always state both the reach and loss budget, for example 500m/2dB, 2km/4dB, or 10km/6dB, or something else. This way, there will be a clear understanding of what application is being addressed.
From: Anslow, Peter [mailto:panslow@xxxxxxxxx]
As previously announced, there is an SMF Ad Hoc meeting starting at 8:00 am Pacific today Tuesday 8 January.
I have currently received two requests for presentations, so the draft agenda is:
<![if !supportLists]>· <![endif]>IEEE patent policy reminder
<![if !supportLists]>o <![endif]>http://www.ieee802.org/3/patent.html
<![if !supportLists]>· <![endif]>Approval of the draft minutes from 18 December call
<![if !supportLists]>· <![endif]>Presentation
<![if !supportLists]>o <![endif]>100G-BASE-WDM4 optical budget constraints Yurii Vlasov, IBM
<![if !supportLists]>o <![endif]>System vendor perspective to NG100GE SMF interface Tek Ming Shen, Huawei
<![if !supportLists]>· <![endif]>Discussion
Both presentations are now available on the SMF Ad Hoc web page.
Peter Anslow from Ciena has invited you to join a meeting on the Web, using WebEx. Please join the meeting 5-10 minutes early so we may begin on time.
+44-203-4333547 (United Kingdom)
4438636577 (United States)
Pete Anslow | Senior Standards Advisor