Tp-Link T3700G-28TQ V2 [274/411] Pim sm

 Configure Switch B and C:

Ste

Operation Description

1 Configure interface Configure IP addresses and subnet masks of VLAN interfaces 2,

3, 4 and 5 on Routing→Interface→Interface Config page.

2 Configure routing

protocol

Configure the routing entries via static route or dynamic routing

protocol like OSPF, and make sure all network can communicate

with each other.

3 Enable multicast

routing and PIM DM

Enable multicast routing on Multicast Routing→Global Config

page. Enable PIM DM on VLAN interfaces 2, 3, 4 and 5 on

Multicast Routing→PIM DM→PIM DM Interface page.

4 Enable IGMP Enable IGMP on the VLAN interfaces 4 and 5 which connect to the

receivers on Multicast Routing→IGMP→Interface Config page.

11.4 PIM SM

PIM DM uses the “flood-and-prune” mode to create the SPT for transferring multicast data.

Although SPT has the short path, its building-up process is of low efficiency and does not apply

to the large and medium-sized network.

PIM SM is a multicast routing protocol in sparse mode. It uses the “Pull Mode” to transfer

multicast data and usually applies to large and medium-sized network with relatively sparse

multicast group members.

The working mechanism of PIM SM is illustrated as below:

 PIM SM assumes that no hosts need to receive the multicast data, the multicast data will not

be forwarded to the host unless there is an explicitly request for the traffic. The core task of

PIM SM to realize multicast forwarding is to build and maintain the RPT (Rendezvous Point

Tree). RPT selects a certain router in the PIM domain as the public RP (rendezvous point),

through which the multicast data is transferred along the RPT to the receivers.

 The router connected to the receiver sends the join message to the RP of a certain multicast

group. The path along which the join message is sent to the RP hop-by-hop forms a branch

of RPT.

 When the multicast source is sending multicast data to a multicast group, the router directly

connected to the multicast source firstly registers to the RP by sending the Register

Message to the RP in unicast mode. The arrival of the register message at the RP triggers

the establishment of the SPT. Then the multicast source sends the multicast data along the

SPT to the RP. The multicast data will be duplicated and distributed to the receivers after

they arrive at the RP.

262