Cisco Systems 78-11741-02 manual Storing IP Multicast Headers, IPC-439

Configuring IP Multicast Routing

Storing IP Multicast Headers

To configure an intermediate IP multicast helper, the first hop router and the last hop router must be configured. To configure the first hop router, use the following commands beginning in global configuration mode:

	Command		Purpose
Step 1
	Router(config)# interface type number		Specifies an interface.
Step 2
	Router(config-if)#	ip multicast helper-map	Configures a first hop router to convert broadcast
	broadcast multicast-address access-list		traffic to multicast traffic.
Step 3
	Router(config-if)#	ip directed-broadcast	Configures directed broadcasts.
Step 4
	Router(config)# ip	forward-protocol udp [port]	Configures IP to forward the protocol you are using.

After configuring the first hop router, use the following commands on the last hop router beginning in global configuration mode:

	Command		Purpose
Step 1
	Router(config)#	interface type number	Specifies an interface.
Step 2
	Router(config-if)#ip directed-broadcast		Configures directed broadcasts.
Step 3
	Router(config-if)#ip multicast helper-map		Configures a last hop router to convert multicast traffic
	group-address broadcast-address		to broadcast traffic.
	extended-access-list-number
Step 4
	Router(config)#	access-listaccess-list-number	Configures an access list.
	{deny permit}	udp source source-wildcard
	destination destination-wildcard port
Step 5
	Router(config)#	ip forward-protocol udp [port]	Configures IP to forward the protocol you are using.

Note On the last hop router, the ip multicast helper-mapinterface configuration command automatically introduces ip igmp join-groupgroup-addresson that interface. This command must stay on that interface for the intermediate IP multicast helper feature to work. If you remove the ip igmp join-groupcommand, the feature will fail.

Storing IP Multicast Headers

You can store IP multicast packet headers in a cache and then display them to determine any of the following information:

•Who is sending IP multicast packets to what groups

•Interpacket delay

•Duplicate IP multicast packets (if any)

•Multicast forwarding loops in your network (if any)

•Scope of the group

•UDP port numbers

•Packet length

Cisco IOS IP Configuration Guide

IPC-439