Configuring Multicast Support for a Stub Network
Troubleshooting Multicast Stub Routing and IGMP
View
Command Syntax
group memberships
show ip igmp groups
stored on the router
multicast routing table show ip mroute
IGMP interfaces
show ip igmp
interface
real-time IGMP
debug ip igmp
messages
real-time IGMP
debug ip igmp
messages for a
<A.B.C.D>
specific group
10-20
Table 10-2. Multicast and IGMP Troubleshooting Commands
Displays
• multicast address
• connecting (downstream)
interface
• uptime and expiration time
• host that last reported on the
group
for each route:
• uptime and expiration time
• incoming interface
• list of outgoing interfaces
for each downstream interface:
• IP address
• whether IGMP is enabled
• IGMP version number
• IGMP intervals
• helper address
• IGMP reports from hosts
• IGMP queries
• IGMP reports from hosts
• IGMP queries
Procedure for Troubleshooting Multicast Stub Routing
1.
Identify the multicast address and network in question.
2.
Verify that the router believes a host group exists for that address on that
network. You do so by viewing IGMP group memberships:
ProCurve# show ip igmp groups
The resulting display lists groups by their multicast address. Check that
an entry exists for the multicast address. The entry should also include
the interface that connects to the network in question.
Function
verify that the router knows that a
group exists on a network
verify that:
• the router can forward
multicasts
• the router will forward
multicasts out the correct
downstream interfaces
• verify that the interface can run
IGMP in the version used on the
network
• check for problems with IGMP
intervals
• view the helper address
verify that the router is receiving
IGMP messages
verify that the router is receiving
IGMP messages for a specific
group