3Com Router User Manual

Configuring IGMP507
Configuring the Version 
Number of IGMP at the 
Router InterfaceIGMP Version 2 is able to configure query message timeout and the maximum 
query response time. All the systems in the same subnet must run the same IGMP 
version because the routers are not able to check the version number of IGMP 
currently running on the interface. 
Make the following configuration in the interface view.
Ta b l e 578   Configure the IGMP Version Number Run at Router Interface
By default, IGMP Version 2...

508CHAPTER 34: CONFIGURING IGMP
The default maximum query response time is 10 seconds but ranges from 1 to 25 
seconds.
This configuration can only be carried out if the current router interface is 
operating IGMP Version 2. 
Configuring Subnet 
Querier Survival TimeWhen there are several routers operating IGMP in a subnet, one router is chosen 
to serve as a querier to take charge of sending query messages to other routers in 
the network segment. In the network initialization, all the routers in the...

IGMP Configuration Example509
Figure 162   IGMP network diagram
1Configure the IP addresses of the interfaces of Router A, Router B and the PC.
[RouterA]interface e0
[RouterA-Ethernet0]ip address 10.16.1.3 24
[RouterB]interface e0
[RouterB-Ethernet0]ip address 10.16.1.2 24
2Execute the multicast routing-enable command on 3Com A and 3Com B to 
enable multicast routing.
[RouterA] multicast routing-enable
[RouterB] multicast routing-enable
Quidway A
PCQuidway B
HUB 10.16.1.3
10.16.1.2
10.16.1.0/24...

510CHAPTER 34: CONFIGURING IGMP 

35
CONFIGURING PIM-DM
This chapter covers the following topics:
■PIM-DM Overview
■PIM-DM Configuration
■Displaying and Debugging PIM-DM
■PIM-DM Configuration Example
PIM-DM OverviewProtocol Independent Multicast--Dense Mode (PIM-DM) is applicable to the 
following conditions: 
■The transmitter and the receiver are close to each other, and there are a large 
number of multicast group receiving members in the network.
■Multicast packet traffic is large. 
■Multicast packet traffic is continuous.
PIM-DM...

512CHAPTER 35: CONFIGURING PIM-DM
operating IGMPv1 (each PIM router periodically broadcasts a hello message, 
and the router with higher IP address is chosen to be the DR).
■Graft Message: The host informs the router which multicast groups it wants to 
join by a IGMP membership report message. At this time, the port sends a graft 
message to the upstream router. After the upstream router receives a graft 
message, it adds this port to the forwarding list of the multicast group. 
■Graft ACK Message: After...

Displaying and Debugging PIM-DM513
Starting the PIM-DM 
ProtocolYou must start the PIM-DM protocol at each interface. By default, the system 
disables the PIM-DM protocol.
Make the following configuration in the interface view. 
Ta b l e 584   Start/Disable PIM-DM Protocol
Configuring the Time 
Interval for Hello 
Messages After the interface starts PIM-DM protocol, it will periodically send to all the PIM 
routers (group address is 224.0.0.13) hello messages to find neighbors. PIM 
query-interval timer...

514CHAPTER 35: CONFIGURING PIM-DM
After making the previous configuration, execute the display command in all 
views to display the running of the PIM-DM configuration, and to verify the effect 
of the configuration. Execute the 
debugging command in system view to debug 
PIM-DM.
PIM-DM Configuration 
ExampleIn this example, the multicast source server is the multicast source, while RECEIVER 
1 and RECEIVER 2 are the two receivers of this multicast group. 
Figure 163   PIM-DM configuration and...

36
CONFIGURING PIM-SM
This chapter covers the following topics:
■PIM-SM Overview
■PIM-SM Configuration
■Displaying and Debugging PIM-SM
■PIM-SM Configuration Example
■Troubleshooting PIM-SM
PIM-SM OverviewProtocol Independent Multicast--Sparse Mode (PIM-SM) is used in the following 
conditions: 
■The distribution of the group members is relatively separate and the range is 
comparatively wide.
■The network bandwidth resource is limited. 
PIM-SM is independent of any specific unicast routing protocol. PIM...

516CHAPTER 36: CONFIGURING PIM-SM
neighbors. The hello message also takes charge of choosing a DR for the router 
operating IGMPv1.
■Register Message: When the DR receives the multicast message sent by the 
host in the local network, it encapsulates it in the register message and unicasts 
it to the RP to distribute the message along the RP tree. The source address in 
the IP header of the register message is DR address, and the destination 
address is RP address. 
■Register-Stop Message: It is unicast...