3Com SuperStack II 3300, User Manual

Page: 135 / 172

Identifying the Problem 135
You have configured a multicast
tunnel, but multicast traffic is not
being routed through it. Check the IP addresses of the
routers at both ends of the
multicast tunnel. The
ip
multicast tunnel display
command should indicate that they
have the remote router as the peer.
If the multicast tunnel display shows
the correct IP address in the peer
field, but no multicast traffic is
being routed through the tunnel,
the tunnel endpoints may not be on
the interfaces that are closest to the
destination. User the
ip multicast tunnel
remove
and
define
commands
to create a multicast tunnel. The
multicast tunnel endpoints must be
on two interfaces that are as close
to each other on the network as
possible.
Multicasts are being routed to other
routers, but not to your hosts. Layer 3 Module is not the IGMP
querier on the VLAN. Ensure that IGMP is enabled using
the
ip multicast igmp
command. See “Enabling and
Disabling IGMP” on page 78. Verify
that the Layer 3 Module is the IGMP
querier for the VLAN by checking
the
ip multicast interface
display
command.
OSPF network is unstable. Layer 3 Module fails to converge
because it is out of memory. This is
indicated by soft restarts, or
memoryFailure errors by the
ip
ospf statistics
command.
Increase the system resources
available to OSPF using the
ip
ospf partition modify
command. See “Modifying Memory
Partitions” on page 106.
On networks with a large amount
of multicast traffic, the intra-router
OSPF multicasts may become lost.
This causes HELLO and LSA
messages to be missed and the
network to destabilize. If appropriate for your network, try
enabling IGMP snooping on the
Switch stack. This reduces multicast
traffic across the network as a
whole, and prioritizes the router
protocol multicasts over other
multicast traffic.
(continued)
Table 36 Identifying Problems with the Layer 3 Module (continued)
Problem Cause Solution