Nexus 3K 100% cpu usage when enable PIM sparse mode on interface vlan


I’ve got an N3k with VLAN that move around 500Mbit of Multicast TV data. When I enable “pim sparse-mode” on this interface vlan, CPU of Nexus goes to 100% and ssh/telnet stop working but I’m still able to access switch through console port.

Why PIM eat resources like this ?
Any idea of what occurs here?


Hello Sebastien

In order to further help you in your troubleshooting process, it would be helpful for you to do some diagnostic commands. Since you still have console access during the high CPU usage, I suggest you run the following commands from there, after activating PIM sparse mode:

  1. issue the show process cpu sorted command to view the processes that are taking up CPU resources. Take a look at this link for more detailed commands.
  2. issue the show ip mroute count command to take a look at the number of packets forwarded for each route.

These commands will give you a better picture of what is going on during high CPU usage.

I hope this has been helpful!