Cisco SX-20 consistently dropping off TMS & Touch 8 sometime lost connection to codec

[Zhang Eric]

Hi Experts,

I'm new to the Cisco forum,  I was wondering if anyone is experiencing the same issue and/or if there is a fix.

we currently have TMS 14.2.2 & a mix of EX-90 & SX-20 all running TC7.1.1.  the SX-20 endpoint however will sometime loss ping and shown in TMS as lost network response or system has been booted.  this is happening even when the endpoint is idle.  sometime when this issue occurs, the touch panel would also drop connection with the endpoint (reboot of touch panel will address the issue).

I have check the switch port status which shows not errors or packet loss, perform a channel test on the data cable with fluke, and the result is passed.

our current network environment is only running IPv4, and I have made the following changes to the endpoint, but can not seems to resolve the problem:

• IP stack: IPv4 instead of dual
• IPv6 DHCPOptions: Off
• assigned static IP to both Codec & touch panel
• force both switch port and codec to 100mb full

I have also attached a log of the endpoint, the last time stamp when event happened was at 10:19am EST.

please advise & thank you in advance

[dana.tong]

Have you configured your NTP server on the CODEC?

[Zhang Eric]

I have found the Root cause of the issue, which the switch's Auto QoS policy is untrusting the endpoint for a short period of time and each time this happens we lose network connectivity  see below:

Jun 11 16:59:25.399: %SWITCH_QOS_TB-5-TRUST_DEVICE_LOST: cisco-phone no longer detected on port Gi6/14, operational port trust state is now untrusted.
Jun 11 16:59:41.719: %SWITCH_QOS_TB-5-TRUST_DEVICE_DETECTED: cisco-phone detected on port Gi6/14, port's configured trust state is now operational.

Is this a known issue or does any one know how this can be resolved?