R3166-R3206-HP High-End Firewalls Network Management Configuration Guide-6PW101

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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 in the public instance:
To do... Use the command...
Remarks
Enter system view system-view —
Configure the maximum number of
entries in the multicast forwarding
table
multicast forwarding-table
route-limit limit
Optional
The default is the maximum number
allowed by the system.
Configure the maximum number of
downstream nodes for a single
multicast forwarding entry
multicast forwarding-table
downstream-limit limit
Optional
The default is the maximum number
allowed by the system.
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… Use the command…
Remarks
Trace a multicast path
mtracert source-address
[ [ last-hop-router-address ]
group-address ]
Required
Available in any view
Displaying and maintaining multicast routing and forwarding
To do... Use the command... Remarks
Display multicast
boundary information
display multicast boundary [ group-address [ mask | mask-length ] ]
[ interface interface-type interface-number ]
Available in
any view
Display multicast
forwarding table
information
display multicast forwarding-table [ source-address [ mask { mask
| mask-length } ] | group-address [ mask { mask | mask-length } ] |
incoming-interface { interface-type interface-number | register } |
outgoing-interface { { exclude | include | match } { interface-type
interface-number | register } } | statistics ] * [ port-info ]
Available in
any view