Configuring IP Multicast Routing
403
IGMP membership report; it then tells the switch, via CGMP, which port
needs to be activated. CGMP must be activated on both the router and the
switch.
CGMP Router Configuration
The router configuration syntax is very simple. It must be applied to the
interface connected to the Catalyst switch. The command is ip cgmp
[proxy]
. The proxy option is used for routers that are not CGMP capa-
ble. It allows them to use the proxy router for CGMP. Here is a sample
configuration:
RouterA#conf t
Enter configuration commands, one per line. End with
CNTL/Z.
RouterA(config)#interface FastEthernet4/0
RouterA(config-if)#ip cgmp
RouterA(config-if)#^Z
RouterA#
!
interface FastEthernet4/0
ip address 172.16.10.1 255.255.255.0
no ip directed-broadcast
ip pim sparse-dense-mode
no ip route-cache
ip igmp join-group 224.2.127.254
ip cgmp
!
Catalyst Switch Configuration
The Catalyst syntax is just as simple, if not more so, as the syntax for the
router configuration. By default, CGMP is turned off on the switch. If you
want multicast to work properly, you must enable CGMP on the switch.
This is done by using the syntax set cgmp enable. Here is a sample:
switch1> (enable) set cgmp enable
CGMP support for IP multicast enabled.
Copyright ©2000 SYBEX , Inc., Alameda, CA
www.sybex.com