router# config term
router(config)# ip multicast-routing
router(config)# int ethernet 1
router(config-if)# ip pim dense-mode
router(config-if)# int ethernet 3
router(config-if)# ip pim dense-mode
The above are the basic commands used to enable multicasting in a Router. In Cisco 6509 the multicasting has to be enabled.
The following link has the multicast configuration for Cisco 6509
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_5_3/cofigide/multi.htm#xtocid5220