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Re: [HSSG] 40G MAC Rate Discussion


There is silicon available today that can run 4 x 10GBASE-KR as an 
aggregated link (4 x 10). It has the advantage that it can support links 
to multiple edge devices or a 40G aggregated link between redundant 
switch fabrics. A single 40G link would be the same cost and would take 
the same real estate as the 4 x 10 links. If you invest to make a new 
generation that can support a single 40G MAC the added value will be 
minuscule, I don't see how you could recoup the investment. On the other 
hand, it would be a similar investment to develop the 100G MAC and such 
a device is more suitable as an uplink for a switch fabric that is 
serving 16 x 10G blades. The 100G MAC, along with the attached fabric 
will be used for the inter-switch links and will be more immediately 
useful, a 40G single MAC would be marginally more useful than the 4 x 10 
you already have. I know where I would bet my investment dollars...


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 
> Gig MAC
> 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.
> applications.
> Thanks,
> Ali