N7K - hardware rate limiter

e-chuah · ‎02-25-2012

Hi, "sh hardware rate-limiter" is showing Layer-3 glean dropped counter increasing. This is referring to packets failing RPF check. Under what scenario will we see this problem ? Is this normal ? Rgds Eng Wee

kitanaka · ‎02-27-2012

Hello Rgds Eng Wee,

L3 gleans are seen when the hardware (forwarding engine) sends the packet to software for assistance,

e.g. resolving an adjacency (ARP).

If the box receives a packet of which destination ip subnet is 192.168.0.1/24 and the box has an interface in the subnet and it does not have arp entry for the ip address, it tries sends the packet to software to solve an adjacency.

This is what you see as L3 gleans. If you see excess L3 glean, it might be packets going to hosts for which the box can not solve arp. If there is no such a device which has 192.168.0.1 in the subment but someone is sending toward the ip address, the box keeps trying to solve arp, sending them to software...

Regards,

Kim.