You absolutely right, Peter! It was my misunderstanding of the switchport logic. After adding vlan 12 to the trunk everything work as well! I will made some traffic capture and lab to dig deeper. Best regards,Dmitriy.

Hi, Albrt !Try to use SPAN session. This feature really helpful for allowing only receive traffic.http://www.cisco.com/c/en/us/tech/lan-switching/port-monitoring/index.html

Hi!There are some material and explanation of voice vlan and native vlan as a cisco's implementation of TAGGED, UNTAGGED traffic, PVID and trunk ports.To check this theory I made a little lab:Here is some illustration and result:SWITCH_1#ping 10.1.12...

Hi!There are some steps If you have some issues with booting in ROMMON:1. Plug a console cable to your switch.2. Power OFF your switch by unplugging power cord.3. Press "Mode" button on a face of your 3750 while reconnecting the power cord and releas...