I have a 3560 running 12.1(19)EA1d on which I configured a 2nd vlan with 2 ports in order to force traffic through a compression device. That is, WAN to router, router to switch port vlan 3, crossover cable from 2nd switch port vlan 3 to switch port vlan 4. All other switch port are in vlan 4 also. CDP expectedly reports vlan mismatch between ports on each end of the crossover cable. Transit traffic flows OK through the switch, but there is an issue with traffic sourced from the switch. If I put the IP address on vlan 3 the switch can ping, Telnet, etc to devices localy on vlan 3 but not the gateway router or anything beyond. If I put the IP address on vlan 2 the switch can ping etc with the gateway and everything beyond but not with anything localy. With the IP on vlan 3 I can get to the switch by telneting to another device on vlan 3 and then telneting back to the switch. What is stopping traffic sourced from the switch from crossing the ports on different vlans connected by the crossover cable?