Configuring The Multicast Forwarding Table Size; Tracing A Multicast Path - HP 4800G Series Configuration Manual

To do...
Configure a multicast
forwarding boundary

Configuring the Multicast Forwarding Table Size

The router maintains the corresponding forwarding entry for each multicast packet it receives.
Excessive multicast routing entries, however, can exhaust the router's memory and thus result in lower
router performance. You can set a limit on the number of entries in the multicast forwarding table based
on the actual networking situation and the performance requirements. If the configured maximum
number of multicast forwarding table entries is smaller than the current value, the forwarding entries in
excess will not be immediately deleted; instead they will be deleted by the multicast routing protocol
running on the router. The router will no longer add new multicast forwarding entries until the number of
existing multicast forwarding entries comes down below the configured value.
When forwarding multicast traffic, the router replicates a copy of the multicast traffic for each
downstream node and forwards the traffic, and thus each of these downstream nodes forms a branch of
the multicast distribution tree. You can configure the maximum number of downstream nodes (namely,
the maximum number of outgoing interfaces) for a single entry in the multicast forwarding table to
lessen burden on the router for replicating multicast traffic. If the configured maximum number of
downstream nodes for a single multicast forwarding entry is smaller than the current number, the
downstream nodes in excess will not be deleted immediately; instead they must be deleted by the
multicast routing protocol. The router will no longer add new multicast forwarding entries for newly
added downstream nodes until the number of existing downstream nodes comes down below the
configured value.
Follow these steps to configure the multicast forwarding table size:
Enter system view
Configure the maximum number of
entries in the multicast forwarding table
Configure the maximum number of
downstream nodes for a single
multicast forwarding entry

Tracing a Multicast Path

You can run the mtracert command to trace the path down which the multicast traffic flows from a given
first-hop router to the last-hop router.
To do...
Trace a multicast path
multicast boundary
group-address { mask |
mask-length }
To do...
mtracert source-address
[ [ last-hop-router-address ] group-address ]
Use the command...
Use the command...
system-view
multicast forwarding-table
route-limit limit
multicast forwarding-table
downstream-limit limit
Use the command...
1-9
Remarks
Required
No forwarding boundary by
default
Remarks
—
Optional
1024 by default.
Optional
128 by default.
Remarks
Required
Available in any view