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This product reached the end of support date on March 31, 2021.

Looking to use second port on our capture card for AMD to correct NIC bandwidth issues


Does anyone have experience trying to use 2 ports from Gigamon to AMD to send traffic? We are dropping packets and having Overrun on our AMD, so to remedy the issue until we are going to try and use both ports on our NIC to get us 20GB of bandwidth through the NIC on each AMD in the Loadshare

My question is will the AMD be able to handle this configuration as we have a LOAD share setup already? Are there any specific config changes needed?





Hi Brian

So you have ~10 Gbps of incoming traffic on the AMD?

Since I don't think you can analyze that amount you have to be filtrering out quite a lot?

Or are you perhaps using a HS AMD?

There is a lot of traffic we are currently not analyzing and we also filter out via our Loadshare.

We have a bottleneck at the Gigamon device and the NIC so hoping this change will solve both.

What I'm getting is, is that you will just move your problem to the AMD.

Unless you have a HS AMD, you will just move your problem to the AMD instead of the Gigamon or the NIC. The first thing that happens in the AMD is that the driver needs to process the packet and put in the ring buffer and then remove the ones it doesn't need. This takes processing power and can potentially impact decodes further down the processing wich are less "important" for the whole chain.


I am not seeing any pressure on the AMD's currently, but we are dropping packets on the NIC. We are ultimately going to add another pair of AMD's in the next few months and We are looking at maybe going to HS speed, but for now I need to get the bottleneck of my Infrastructure out of the way.

So having said all this do you know the answer to my initial question?



Dynatrace Pro
Dynatrace Pro

Brian, If you're not monitoring all the traffic, use the gigamon to filter it. That will take the load off of the NIC and AMD.

But to answer your question as asked, yes you can run multiple capture NICs on an AMD.

Will it help your situation? That's harder to answer. Are the NICs running the customised driver? If not why?

A busy 10Gbps port will be too much for an AMD running native mode drivers - you'll find CPU0 on the AMD being heavily utilised by softirq (NIC interrupts). With the customised drivers, that initial filtering load is done on the NIC's processor, not the AMD CPUs.


Hi Brian

There is no Yes/No answer to your question, just as Chris is saying.

It will depend on the mix of the packets you process. Bigger packets are easier to process while smaller requires the IRQ to be pulled for each and every one. I also second Chris point that you should use the customized driver and filter as much as possible outside the AMD.