
Cisco Hoot and Holler over IP Configuration Tasks
13
Cisco IOS Release 12.1(5)T
Configuring Multicast Routing (Required)To enable multicast routing on the platform, perform the following steps:
Configuring the Virtual Interface (Required)To configure the virtual interface for multicast fast switching, perform the following steps:
Configuring VoIP Dial Peers (Required)To configure the VoIP dial peers on the router, perform the following steps:
Command Purpose
Step1 Router(config)# ip multicast-routing Enables multicast routing.
Command Purpose
Step1 Router(config)# interface vif1 Defines a virtual interface for multicast fast 
switching. Routers joining the same session must 
have their virtual interfaces on different subnets. 
Otherwise, packets are not switched to the IP 
network.
Step2 Router(config-if)# ip address address subnet-mask Assigns the IP address and subnet mask for the 
virtual interface.
Step3 Router(config-if)# ip pim { sparse mode | dense-mode | 
sparse-dense-mode }Specifies Protocol Independent Multicast (PIM). 
Whatever mode you choose should match all the 
interfaces in all the routers of your network.
Command Purpose
Step1 Router(config)# dial-peer voice tag voip Assigns a variable number (tag) to the VoIP dial 
peer.
Step2 Router(config-dial-peer)# destination-pattern 
multicast-session-number
The destination pattern for the VoIP dial  peer must 
match the value of the multicast-session-number 
string for the corresponding voice port.
Step3 Router(config-dial-peer)# session protocol multicast This step is mandatory for voice multicasting and 
is the command introduced specifically for the 
Cisco Hoot and Holler over IP application.
Step4 Router(config-dial-peer)# session target 
ipv4:address:port
Assigns the session target for voice multicasting 
dial peers. This is a multicast address in the range 
224.0.1.0 to 239.255.255.255 and must be the 
same for all ports in a session.
The audio RTP port is an even number in the range 
16384 to 32767, and must also be the same for all 
ports in a session. An odd-numbered port 
(UDP port number + 1) is used for the RTCP 
traffic for that session.