IE实验中的多播资料(转)[@more@]

　　Helper-map for Broadcast to multicast conversion and vice versa.

　　The following is an example which illustrates the use of the helper-map command at the first-hop and the last-hop, to convert a broadcast stream directed to port 2000 to a multicast stream and back.

　　

　　On the first hop router

　　-----------------------

　　The following example converts broadcast streams to port 2000 to a multicast stream(G = 224.5.5.5)

　　

　　int < ... > /* incoming interface of broadcast stream */

　　ip multicast helper-map broadcast 224.5.5.5 101

　　ip pim dense

　　.....

　　

　　ip forward-protocol udp 2000

　　access-list 101 permit udp any any eq 2000

　　access-list 101 deny udp any any

　　

　　On the last hop router

　　---------------------

　　

　　int <...> /* incoming interface of multicast stream */

　　ip multicast helper-map 224.5.5.5 178.21.34.255 101

　　ip pim dense

　　.....

　　

　　

　　ip forward-protocol udp 2000

　　access-list 101 permit udp any any eq 2000

　　access-list 101 deny udp any any

　　

　　Note:

　　o Configuring the multicast helper map command (to convert multicast to

　　broadcast) will also automatically configure "ip igmp join-group "

　　on the interface. The router must be joined to the multicast group to be translated to a broadcast address.

　　o In Cisco IOS 12.0, it is necessary to configure the interface command "ip directed-broadcast" along with helper-map command. By default, it is turned off.