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Packet capture with Nexus 1000V

January 20th, 2015

Today I thought I’d take a look at creating a SPAN session on the 1000v to monitor traffic. I found it really easy to do! SPAN is one of those things that takes you longer to read and understand than to actually configure. I find that true with a lot of Cisco products: Fabric Path, OTV, LISP, etc.

SPAN is “Switched Port Analyzer”. Its basically port monitoring. You capture the traffic going from one port and then mirror it on another. This is one of the benefits you get out of the box for the 1000v that enables the network administrator not to have this big black box of VMs.

First I need to see which vethernet is assigned to which VM. This command can help you do that


Then create a monitor session with the following commands

And confirm the monitor session with the command


In this case, we have an error. The state is “Down”. That is because VMTEST1 and VMTEST2 are in 2 difference VM Hosts. After moving them to the same host, the state will change to up