[c-nsp] Cat 6500 spec

[Tim Stevenson]

Sorry, that's wrong. The A card has the exact same 8:1 
oversubscription & follows the same architectural model as the non-A 
at a high level (8 ports per "stub" ASIC connecting to aggregation ASIC(s)).

But the ASICs in the A version are more capable and have some 
advantages (per port vs shared buffers and jumbo frame support for 
example). But there is still **one Gig bandwidth between each group 
of 8 ports & the bus** and you'll never get more than 6G out of this card.

HTH,
Tim

At 12:33 PM 7/8/2006 +1000, David J. Hughes muttered:


>On 07/07/2006, at 7:09 AM, Asbjorn Hojmark - Lists wrote:
>
> >> But if you want something that isn't over-subscribed within
> >> an inch of it's life you'd go with a WS-X6148A-GE-TX rather
> >> than a WS-X6148-GE-TX.
> >
> > You're right, you should use the A version, but not because of
> > the over-subscribtion, which is the same on both modules (8:1).
>
>Actually, no, thats not the case as I understand it.  From what I have
>been told (and I'd appreciate someone from Cisco either confirming or
>denying this) the 6148 is 8:1 oversubscribed because it is equipped
>with only 6 GigE ASICs so each ASIC is shared by a block of 8 ports.
>This gives the linecard a max throughput of 6 gbps over the 48 GigE
>ports and hence the 8:1 oversubscription.
>
>I have been told that the 6148-A is equipped with 48 GigE ASICs so that
>each port has it's own ASIC.  The oversubscription of this linecard is
>48:32 (i.e.  1.5:1) because it is attached to the classic bus and as
>such limited to 32 gbps throughput.
>
>
>David
>...
>
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Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Catalyst 6500
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759
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