Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Packet Loss Issue - Simple Fix?

We have a packet loss issue when pinging from a switch to another switch. We believe this packet loss issue may be the cause of a customer complaint.

In doing some testing, I see the packet loss issue, but as soon as I enable debugging, it goes away. What's going on here?


Sending 50, 2000-byte ICMP Echos to 68.115.X.Y, timeout is 2 seconds:

With debugging off:

Success rate is 38 percent (19/50), round-trip min/avg/max = 16/23/48 ms

With debugging on:

Success rate is 100 percent (50/50), round-trip min/avg/max = 16/25/60 ms

New Member

Re: Packet Loss Issue - Simple Fix?

Here's the debug we are running:

access-list 155 permit icmp any host 68.115.X.Y log

access-list 155 permit icmp host 68.115.X.Y any log

debug ip packet 155 detail


Re: Packet Loss Issue - Simple Fix?

Please post a SH INT for the affected interface(s); a SHOW BUFFERS might be useful as well.

Packet drop / loss is usually either congestion, as seen by the transmitter, {or | which causes} queuing timeouts.

The congestion can be the receiver's inability to catch the traffic being pushed to it. This happens a lot when you have asymmetrical bandwidth (one end is a T1, the other is a 56K DDS or Frac T1, for example).

Hall of Fame Super Gold

Re: Packet Loss Issue - Simple Fix?

Debug enabled and you have zero packet loss? I smell an IOS bug. What's the IOS you are using?

New Member

Re: Packet Loss Issue - Simple Fix?

IOS is Version 12.2(44)SG

CreatePlease to create content