WS-6724-SFP with and without DFC3B in the same chassis

Unanswered Question
Mar 15th, 2007

Hi,

I have WS-6724-SFP cards with and without DCF3B daugther card in the same chassis.

How will the fact that some cards have DFC3B and others do not affect the forwarding performance?

For exemple, when I have Etherchannels configured that use ports in both card types how does this affect the potential benefit of having DFC3B daugther cards?

Thanks in advance,

Ricardo

I have this problem too.
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Amit Singh Thu, 03/15/2007 - 10:23

Ricardo,

This will not help you in great deal.To get the optimized performance you should have DFC on both the line cards. Having DFC on one line card and not the other one, will not give a good peformance.You should have DFC's installed on all the line cards in the chassis. Either all the cards should have DFC or none of them.

HTH,Please rate if it does.

-amit singh

rlourenco Thu, 03/15/2007 - 10:30

Amit,

Thanks for your answer.

I suspected that.

Can you be a little more specific on the consequences (probably they will depend on traffic flows, i.e incoming and outgoing line card, and configured features such as etherchannel) or provide me url links to additional documentation?

Thanks once again.

Ricardo

Amit Singh Thu, 03/15/2007 - 10:53

Ricardo,

DFC is eventually a PFC daughter card which is there on the sup engine. Once you have DFC enabled on the card, it will have all the layer2 and layer 3 tables downloaded locally on it and does the local re-writing of the packet without going to the PFC on the sup engine.The traffic between the ports on the same DFC enabled module will see a little improvement. The traffic between the DFC module and the other non dfc module will use the 32 gbps shared backplane for forwrading the traffic. When all the line cards are DFC enabled, they use Switch fabric (Integrated on Sup 720) to switch all the traffic and the 32 GBps shared bus doesnot come into the picture.That's why you see a very good optimization when you have DFC's on all the line cards.

http://www.cisco.com/en/US/products/hw/switches/ps708/products_qanda_item09186a0080159963.shtml

HTH,

-amit singh

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