Analyzing the ping packet loss over the directly connected link

Ping packet loss

1. Verify the total number of ICMP Echo requests being sent by the local host.

2. Verify the show system statistics icmp , to know the generated ICMP ECHO requests in the Output Histogram.

3. Verify the same command in the neighboring device for ICMP ECHOs in the Input Histogram

4. Ideally these two counters should match.

5. Verify the echo reply in the Output Histogram.

6. Verify the echo reply in the Input Histogram.

7. If there are any mismatches in either direction, apply the firewall filter on the interface preferably at both ends matching to the source/destination IP address and matching to the ICMP.

8. The filter should have count option.

9. if there is no packet drop, Firewall Filter counter will report matching numbers on both sides.

10. If there is a drop, based on the firewall counter output, the troubleshooting direction can be focused.

11. If the local device filter count matches to the sent packets, then look at the firewall counters at the remote side.

12. if firewall counters at the remote side also the same, look at the show system statistics icmp output or monitor traffic interface <intf_name> matching icmp output to narrow down further.