A L3 or L2 tunnel, including tunnel bridge ports, can be configured as the TWCB outbound interface by entering the appropriate TWCB redirect out command within the tunnel interface configuration mode.
Use the {ip | ipv6} twcb webcache-name redirect out, in tunnel interface command mode, to enable the interface as a TWCB outbound interface.
See Transparent Web Cache Balancing (TWCB) Configuration for TWCB configuration details.