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Re: [HSSG] 40G MAC Rate Discussion

Joel, maybe the 100Gbs target should be 120Gbs. Ribbon fiber cables and the connectors are x12. Assuming a 10Gbs per channel implementation, this works our very nicely. Many copper cables and connectors are also already established at x12. Then the 120Gbs interface could be broken out into 3 40Gbs interfaces or 12 10Gbs interfaces without loosing bandwidth.

Jim McGrath
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From: Joel Goergen []
Sent: Thursday, April 05, 2007 2:07 PM
Subject: Re: [HSSG] 40G MAC Rate Discussion


If the front end is defined as 100Gbps, expecting the back end to be 40Gbps makes no sense from system implementation.  Maybe if it were 50Gbps, the TM might be easier to implement.  But either way, you would throw away a lot of bandwidth for a 100 going into 40.

Also, if the front end moves towards 4by25+FEC, which it appears to be based on the work so far, from a system perspective, you would use the same data rate on the back end side with perhaps different signaling.  Further, spending another three years on a 40Gbps back plane standard for such a small gain doesn't seem right.  It was pretty painful the last time around.  You would end up defining 1by40Gbps, 4by10Gbps, 16by3.125Gbps.  I just don't see the ROI.

No one has yet to prove that 4by10Gbps LAG doesn't fit the server market described by Shimon.  And actually, I still don't see the market he is talking about.  Regardless of using LAG on the front end or in an ATCA chassis with multiple LAG connections ... a solution exists today that works well.

Last is someone still has to design an aggregation box to connect all the 40Gs together and pipe them out 100Gs.  I "know the art", and it is very costly to do this.  But that isn't the problem for me ... we can all burn the money to supply a market we've seen no data for or a description of ... the real problem for the systems vendor is we finish the box in 2010 and we have the exact same data performance problem we have today jamming 1G and 10G links into a 10G core.

I propose that rather then do 40G, we put that effort into working with 802.1 to resolve the perceived problems with LAG.  Thus when 100Gbps is complete, we will have a N-LAG ... or New LAG ... that allows the end user to create ANY size pipe required for 1G, 10G, and 100G core or ag implementations.


Ali Ghiasi wrote:

Marcus and Others

I like to present another point of view in support of 40 Gig MAC.
We currently have the following option on the backplane side
    - KX-4 (XAUI) 10Gig
    - KR (1 lane ) 10Gig
The natural next step for backplane Ethernet will be to operate KX-4
lanes at 10.3125 Gbaud.
Regardless of what decision we make in the HSSG 40Gig MAC will exist for
the backplane.

Assuming we will define the 40Gig MAC sooner or later then allowing 40
for front panel becomes even more compelling, specially when 100Gig is
overkill for these
applications in near term.  If we define 40Gig MAC in the HSSG then
defining 40Gig
backplane becomes travail.



Marcus Duelk wrote:
> Hi,
> I think it was common sense at the last meeting that the
> rate that service providers and IXPs are looking for is 100 GbE.
> The discussion about 40 GbE is for the *server market*, the
> classical LAN application of Ethernet. In the network space you
> have already OTU3 and OC-768c PoS, so there is not much
> need for another 40G Ethernet interface.
> Also, my personal opinion is regarding "broad market potential"
> that there will be more networks or network types that require
> 100 GbE, however in terms of volumes I could imagine that a 40GbE
> interface for servers will actually produce more volumes, even though
> it is only one type of network.
> Marcus
> Toshinori Ishii wrote:
>> Hello,
>> I'm another IXP network engineer.
>> 2007/4/5, Henk Steenman <>:
>>> Back to 40GE: scaling link aggregation using 10GE for another 3 years
>>> will be very hard. The use of 40GE might be of help here if it would
>>> allow for standardized products to become available say second half
>>> of 2008.
>>> QUESTION: Is there a way to expedite the standardization process (and
>>> subsequent product development) of a 40GE standard? Within or outside
>>> of the IEEE?
>>> If the answer to the above is "no" then I would say lets not spend any
>>> time on anything other than 100GE so no delay is introduced in the
>>> development of this standard and get it finished as soon as possible.
>> Agree.
>> I need 100GE ASAP.

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