Intermittent packet drop when ping from switch to IP phones

[dacigocesar]

I observed when i perform 100 ping from my switch to ip phone, i will observe intermittent packet drop but this does not happen when i ping from a workstation to the ip phone.

Is this normal or any misconfiguration in my switch?

Below is the config for my switch port

interface FastEthernet1/0/2

switchport access vlan 112

switchport trunk native vlan 112

switchport voice vlan 131

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

mls qos trust device cisco-phone

mls qos trust cos

auto qos voip cisco-phone

storm-control broadcast level 30.00 20.00

storm-control action trap

spanning-tree portfast

[paolo bevilacqua]

That is normal, by design the phone drops ping in excess above a certain rate.

The PC succeeds always because it waits for ping reply before sending next request.

Hope this helps, please rate post if it does!

[mattcalderon]

Thanks Paulo. 5 points for that! I was running into this exact problem. Does this only pertain to certain phone series or is this across the board on all phones both sccp and sip?

[paolo bevilacqua]

For sure the 7940-60. Sorry, I don't remember about all the other types.

[Manish Gogna]

Hi Matt,

It's a built in anti-DoS method in the phone that drops ICMP packets when they're sent really fast to the phone. It's implemented across the whole third generation phone base, including 7911, 7931, 7941/61 7965/45 , 7970, 7975 and others.

HTH

Manish