Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Attention: The Community will be in read-only mode on 12/14/2017 from 12:00 am pacific to 11:30 am.

During this time you will only be able to see content. Other interactions such as posting, replying to questions, or marking content as helpful will be disabled for few hours.

We apologize for the inconvenience while we perform important updates to the Community.

New Member

Intermittent packet drop when ping from switch to IP phones

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

4 REPLIES
Hall of Fame Super Gold

Re: Intermittent packet drop when ping from switch to IP phones

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!

Re: Intermittent packet drop when ping from switch to IP phones

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?

Hall of Fame Super Gold

Re: Intermittent packet drop when ping from switch to IP phones

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

Cisco Employee

Re: Intermittent packet drop when ping from switch to IP phones

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

2243
Views
10
Helpful
4
Replies
CreatePlease to create content