User's Manual

48-51
router)
Configurations are listed as below:
switch#config
switch(config)#ip pim multicast-routing
switch(config)#interface vlan 100
switch(config-if-vlan100)#ip pim sparse-mode
IGMP snooping does not distribute entries when layer 3 multicast protocol is enabled. It only does the
following tasks.
 Remove the layer 2 multicast entries.
 Provide query functions to the layer 3 with vlan, S, and G as the parameters.
 When layer 3 IGMP is disabled, re-enable distributing layer 2 multicast entries.
By looking up the layer 3 IPMC entries, it can be found that ports can be indicated by the layer 3 multicast
entries. This ensures the IGMP snooping can work in cooperation with the layer 3 multicast protocols.
48.10.4 IGMP Snooping Troubleshooting
On IGMP Snooping function configuration and usage, IGMP Snooping might not run properly because of
physical connection or configuration mistakes. So the users should note that:
 Make sure correct physical connection
 Activate IGMP Snooping on whole configuration mode (use ip igmp snooping)
 Configure IGMP Snooping at VLAN on whole configuration mode (use ip igmp snooping vlan
<vlan-id>)
 Make sure one VLAN is configured as L2 common checker in same mask, or make sure configured
static mrouter
 Use show ip igmp snooping vlan <vid> command check IGMP Snooping information
48.11 IGMP Proxy Configuration
48.11.1 Introduction to IGMP Proxy
IGMP/MLD proxy which is introduced in rfc4605, is a simplified multicast protocol running at edge boxes. The
edge boxes which runs the IGMP/MLD proxy protocol, does not need to run complicated multicast routing
protocols such as PIM/DVMRP. However they work with multicast protocol enabled network through
IGMP/MLD proxy. They can simplify the implementation of multicasting on edge devices.
The IGMP/MLD proxy works between the multicast router and the client, it works as both the multicast host