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Re: [HSSG] 40G MAC Rate Discussion


    I'd like to notice that for NRZ modulation CD limited reach over SSMF
(G.652) at 25G speed is about 16km. But at 30G it will be 11km only even
with FEC less.

Best regards,


Josef Vojtech
CESNET a.l.e.
Zikova 4
160 00 Prague 6
Czech Republic

tel: +420224352912

----- Original Message ----- 
From: Joel Goergen
Sent: Thursday, April 05, 2007 10:37 PM
Subject: Re: [HSSG] 40G MAC Rate Discussion


Please look at past data regarding optic feasibility for 10km solution 
space.  The optics vendors are suggesting 4by25+FEC as a good fit.  I'm 
pretty uncomfortable pushing that to 4by30+FEC.


McGrath, Jim wrote:

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
2222 Wellington Ct
Lisle, IL 60532
Phone: 630-527-4037
Mobile: 630-244-3872
Fax: 630-969-1352

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 

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 


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.

fn:Ali Ghiasi
adr;dom:;;3151 Zanker Road;San Jose;CA;95014
title:Chief Architect