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2x10GE Portchannel on a CAT4900M with 8x10GE (2:1) card does not exceed 10GE of througput


Hello team:

We have a 2x10GE (layer3) portchannel established between a ASR1006 and a CAT4900M.

The 2x10GE ports on the CAT4900M belong to a 8x10GE(2:1) card.

Traffic from servers connected to the ASR1006 router down to clients behind the CAT4900 on this portchannel does not exceed 10Gbps, although we know that traffic should reach at least 14Gbps.

We suspect that something in the architecture of the 8x10GE(2:1) card is limiting the effective 20Gbps throughput that should be achieved on this portchannel.

¿ Has anyone experienced a problem like this?

I browsed through the web looking for the architecture of this 8x10GE(2:1) card on the CAT4900M but found nothing.

Any help will be greatly appreciated.

Thanks in advance

Rogelio Alvez


2 Replies 2

Jon Marshall
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I can't find any specific information in terms of port groups etc for that module.

All I could find is that it has a 40Gbps switch fabric connection so I assume all ports simply share that connection.

So the only things I can think of are do you have any other ports in use on that module and what is the load balancing method in use on the ASR ?

I think the default load balancing method is source and destination IP which for a L3 etherchannel would make sense.

I am also assuming that the amount of traffic you know is being sent is not between just one client and server ?


Hi Jon:

The remaining 10GE ports on both sides are idle. And there are many high-end servers connected to the ASR1006 and at least 50,000 clients downstream of the CAT4900M.

The portchannel balancing algorithm is the default one.

Next week we will test another approach: we will untie the portchannel and build two /30 subnets (each one for each 10GE link). We will see whether this strategy works better.

I will keep you posted. 

Thanks! Rogelio

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