10Gig - 8port Line Cards

Unanswered Question
Oct 2nd, 2007

I need to install these cards into a Dist switch that will aggregate Access uplinks. How much bandwidth is avail per port on the 4-port and 8-port line card?? Using Sup 720 - how does the 10G factor in? Help - I need to scale a new network and need the calcs. Thanks.

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Jon Marshall Tue, 10/02/2007 - 23:23


I's sure you have seen this doc but attached is a link covering these modules.


Both switches have a 40Gbps connection to the switch fabric so with a 4 port 10Gbps module there should be no oversubscription. With an 8 port 10Gbps module you are oversubscribed 2:1.

However you should look at the comparison doc above as the modules do have different port buffers/QOS capabilities so this may affect your decision.

Also attached is a doc specifically for the 8 Port module. You can avoid oversubscription if you only use ports 1,2,5,6 and there is even a config command to make this happen - see doc for details.




Joseph W. Doherty Wed, 10/03/2007 - 04:10

Within Jon's information, note the 8 port 10 gig cards come standard with DFC, the 4 port 10 gig cards do not. Without DFCs, the sup720 is good for about 20 Gbps (64 byte packets @30 Mpps) for the whole chassis using fabric line cards. With DFCs, cef720 line cards, themselves, are good for about 32 Gbps (64 byte packets @48 Mpps). (NB: The only 6500 10 gig line card that was rated true wirespeed was the 2 port 10 gig.)

Keeping the above in mind, you can obtain required performance on the higher port cards by using less ports. And as Jon also noted, the 8 port 10 gig card even has a config command that disables half the ports.

In practice, from distribution to user access, the 8 port 10 gig card will likely be fine using all its ports. For 10 gig to server access or from distribution to core, you might need to use less 10 gig ports per card.

Lastly, I believe you can channel up to 8 10 gig ports. If you need that level of inter-device bandwidth, again, keep in mind the bandwidth and Mpps limitations per chassis and slot.


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