Intermittent ping to Cisco IP Phone

[Sgj]

Hello,

When I test ping rep 100 from Core to Cisco IP Phone 3905, it's fine

CORE-01#ping 10.83.242.136 rep 100
Type escape sequence to abort.
Sending 100, 100-byte ICMP Echos to 10.83.242.136, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (100/100), round-trip min/avg/max = 1/1/8 ms

But when I test ping rep 100 from Core to IP Phone 6921, there's an intermittent

CORE-01#ping 10.83.237.131 rep 100
Type escape sequence to abort.
Sending 100, 100-byte ICMP Echos to 10.83.237.131, timeout is 2 seconds:
!!!!!!.!!!!!.!!!!!.!!!!!!!.!!!!!.!!!!!.!!!!!!!!!.!!!!!.!!!!!.!!!!!!!!!
.!!!!!.!!!!!.!!!!!!!!.!!!!!.!!

Success rate is 86 percent (86/100), round-trip min/avg/max = 1/1/4 ms

Any knows what happens with this? Maybe the config or anything else?

Thanks in advanced

[balaji.bandi]

Can you post the port configuration along with any QoS  configured.

[Sgj]

Thanks for the reply,

This port was used for IP Phone 3905 :

interface GigabitEthernet1/0/18
 description CONNECT TO USER
 switchport access vlan 290
 switchport mode access
 switchport voice vlan 293
 mls qos trust device cisco-phone
 mls qos trust cos
 spanning-tree portfast

This port was used for IP Phone 6921 :

interface GigabitEthernet1/0/8
 description CONNECT TO USER
 switchport access vlan 290
 switchport mode access
 switchport voice vlan 293
 mls qos trust device cisco-phone
 mls qos trust cos
 spanning-tree portfast

[Jahangir Tahirov]

Can you tried ping from the PC?

cause may be phone itself not able to reply all of the icmp packets sent from the router.

[Sgj]

Is there any configuration for this type of IP Phone 6921?

[Nithin Eluvathingal]

 do you face any issues with  calls ?

[Sgj]

Yes, because the CDR shows cause code 41.

And now I'm still looking for the cause with valid data

[Nithin Eluvathingal]

This intermittent ping drop is expected.

you need to look in all components which involved in the voice communication.

Can you provide more information regarding your setup.

[Sgj]

Sorry,

What kind of "setup" do you mean?

The configuration or what ?

[Roger Kallberg]

This is expected. Some models of phones has a built in protection for ICMP, it will drop packages to offload the CPU.

[Sgj]

Do you mean like IP Phone 6921 type?

[Roger Kallberg · Accepted solution]

Was awhile ago since I had anything to do with that awful line of phones, but if memory serves me yes that model would have this protection.