Intermittent packet drop when ping from switch to IP phones

Unanswered Question
Mar 3rd, 2008

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

I have this problem too.
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Overall Rating: 5 (2 ratings)
Paolo Bevilacqua Tue, 03/04/2008 - 02:19

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 Tue, 03/04/2008 - 05:10

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?

Manish Gogna Fri, 10/04/2013 - 06:43

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.




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