WS-X6416 vs WS-X6516 GBIC card question

Unanswered Question
May 18th, 2007

I'm reading a cisco doc and it says

Performance/Forwarding Rate for the two module:

WS-X6416-GBIC is Mpps 32 Gbps 15 Mpps per system

WSX6516-GBIC is 256 Gbps using CEF: Up to 30 Mpps per system

My questions is: Using 6416 with SUP720, will overall chassis performance be 32Gbps or the performance of the slot where the card is in. I plan on using 6516 in slot 1 and 6416 in slot2.

Thank you all in advance.

I have this problem too.
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Jon Marshall Fri, 05/18/2007 - 12:39

Hi

If you use the 6416 it will not reduce the overall chassis performance to 32Gbps. What will happen is that the 6416 will share the 32Gbps with any other module that is only "classic" line speed.

The 6516 will still utilise it's fabric enabled connection ie. it will have a 8Gbps dedicated (not shared) connection to the switch fabric.

What does happen if you mix fabric enabled with non-fabric enabled is that the switching mode changes from compact to truncated mode. From a Cisco 6500 doc

=============================================

Switching Modes

When you install a Switch Fabric Module, the traffic is forwarded to and from modules in one of the following modes:

?Compact mode?The switch uses this mode for all traffic when only fabric-enabled modules are installed. In this mode, a compact version of the DBus header is forwarded over the switch fabric channel, which provides the best possible performance.

?Truncated mode?The switch uses this mode for traffic between fabric-enabled modules when there are both fabric-enabled and nonfabric-enabled modules installed. In this mode, the switch sends a truncated version of the traffic (the first 64 bytes of the frame) over the switch fabric channel.

?Bus mode?The switch uses this mode for traffic between nonfabric-enabled modules and for traffic between a nonfabric-enabled module and a fabric-enabled module. In this mode, all traffic passes between the local bus and the supervisor engine bus.

=============================================

The Cisco engineers i have spoken with cannot be specific on how much degradation you get when you go from compact to truncated as it depends on size of packets.

HTH

Jon

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