[c-nsp] x6148 vs. x6548

[Tim Stevenson]

Mike, please see inline below:

At 10:45 AM 7/16/2009, M Callahan opined:
>We have several 3560G switches deployed as access switches in a 
>small data center environment.  With the increased use of Gig at the 
>access layer, the notion of using EtherChannel to get increased 
>uplink bandwidth back to a WS-X6548-GE is something we've been 
>discussing recently too.  As has been discussed, this won't work the 
>way we'd like it to due to the over subscription design of the 
>X6548. That said, would an EtherChannel setup between the SFP ports 
>on the 3560G and a X6516-GBIC card in the 6509 have any similar type 
>of limitation, or would it work to acheive the increased uplink bandwidth?

6516 is basically 16 1G ports feeding into a single 8G fabric 
channel, so 2:1 oversubscribed if all ports are pumping. But it's not 
port level oversubscription, so you could definitely use this card & 
it is very typically used in this manner.

You just need to engineer it such that enough uplink b/w and agg 
layer capacity exists to support the access layer, based on the 
environment. Oversubscription ratios are very application/environment 
specific, anywhere from 1:1 all the way to 20:1 or more, so some 
baselining etc might be in order.

>
>
>Also, is the only difference between the WS-X6516-GBIC and the 
>WS-X6516A-GBIC the per port buffer size?

Of the top of my head, that, and the replacement of Titan/Medusa 
chips with the Hyperion ASIC for multicast replication & fabric 
interface. Hyperion permits the use of egress replication with the A 
version of the card.

HTH,
Tim




>Thanks,
>
>Mike




Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Cisco Nexus 7000
Cisco - http://www.cisco.com
IP Phone: 408-526-6759
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