3Com 8807 Configuration Manual page 461

PIM-DM Configuration Example 461
[SW8800] interface vlan-interface 10
[3Com-vlan-interface10] ip address 1.1.1.1 255.255.0.0
[3Com-vlan-interface10] pim dm
[3Com-vlan-interface10] quit
[SW8800] interface vlan-interface 11
[3Com-vlan-interface11] ip address 2.2.2.2 255.255.0.0
[3Com-vlan-interface11] pim dm
[3Com-vlan-interface11] quit
[SW8800] interface vlan-interface 12
[3Com-vlan-interface12] ip address 3.3.3.3 255.255.0.0
[3Com-vlan-interface12] pim dm
2 Configuration on Lanswitch2, (configuration on Lanswitch3 is similar)
# Enable the multicast routing
<SW8800>system-view
System View: return to User View with Ctrl+Z.
[SW8800] multicast routing-enable
# Enable IGMP and PIM-DM on the interface
[SW8800] vlan 11
[3Com-vlan11] port ethernet 2/1/2
[3Com-vlan11] quit
[SW8800] vlan 12
[3Com-vlan12] port ethernet 2/1/4
[3Com-vlan12] quit
[SW8800] vlan 20
[3Com-vlan20] port ethernet 2/1/6
[3Com-vlan20] quit
[SW8800] interface vlan-interface 11
[3Com-vlan-interface11] ip address 1.1.1.2 255.255.0.0
[3Com-vlan-interface11] pim dm
[3Com-vlan-interface11] quit
[SW8800] interface vlan-interface 12
[3Com-vlan-interface12] ip address 2.2.2.2 255.255.0.0
[3Com-vlan-interface12] pim dm
[3Com-vlan-interface12] quit
[SW8800] interface vlan-interface 20
[3Com-vlan-interface20] ip address 3.3.3.2 255.255.0.0
[3Com-vlan-interface20] igmp enable
[3Com-vlan-interface20] pim dm
n
You should enable PIM-DM on all equal-cost routes if there are any.