Configuring Pim-Sm - 3Com Switch 7700 Configuration Manual

216 C 6: M
HAPTER ULTICAST

Configuring PIM-SM

P
ROTOCOL
Configuration procedure
This section only provides the configuration for Switch A because the
configuration procedures for Switch B and Switch C are similar.
1 Enable the multicast routing protocol.
[SW7700] multicast routing-enable
2 Enable PIM-DM.
[SW7700] vlan 10
[SW7700-vlan10] port Ethernet 1/0/2 to Ethernet 1/0/3
[SW7700-vlan10] quit
[SW7700] vlan 11
[SW7700-vlan11] port Ethernet 1/0/4 to Ethernet 1/0/5
[SW7700-vlan11] quit
[SW7700] vlan 12
[SW7700-vlan12] port Ethernet 1/0/6 to Ethernet 1/0/7
[SW7700-vlan12] quit
[SW7700] interface vlan-interface 10
[SW7700-vlan-interface10] ip address 1.1.1.1 255.255.0.0
[SW7700-vlan-interface10] igmp enable
[SW7700-vlan-interface10] pim dm
[SW7700-vlan-interface10] quit
[SW7700] interface vlan-interface 11
[SW7700-vlan-interface11] ip address 2.2.2.2 255.255.0.0
[SW7700-vlan-interface11] igmp enable
[SW7700-vlan-interface11] pim dm
[SW7700-vlan-interface11] quit
[SW7700] interface vlan-interface 12
[SW7700-vlan-interface12] ip address 3.3.3.3 255.255.0.0
[SW7700-vlan-interface12] igmp enable
[SW7700-vlan-interface12] pim dm
PIM-SM (Protocol Independent Multicast, Sparse Mode) belongs to sparse mode
multicast routing protocols. PIM-SM is mainly applicable to large-scale networks
with broad scope and few group members.
Different from the flood & prune principle of the dense mode, PIM-SM assumes
that all hosts do not need to receive multicast packets, unless clear request is put
forward.
PIM-SM uses the RP (Rendezvous Point) and the BSR (Bootstrap Router) to
advertise multicast information to all PIM-SM routers and uses the join/prune
information of the router to build the RP-rooted shared tree (RPT). This helps to
reduce the bandwidth occupied by data packets and control packets, and reduces
the process overhead of the router. Multicast data flows along the shared tree to
the network segments. When data traffic is sufficient, the multicast data flow
switches over to the SPT (Shortest Path Tree) rooted on the source. This reduces
network delay. To perform the RPF check, PIM-SM does not depend on the
specified unicast routing protocol but uses the present unicast routing table.
Running PIM-SM, you would need to configure candidate RPs and BSRs. The BSR
is responsible for collecting the information from the candidate RP and advertising
the information.