H3C Technologies H3C S12500 Series Switches - Manual (Page 84)

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When forwarding multicast traffic, the router replicates a copy of the multicast traffic for each
downstream node and forwards the traffic. Thus, each of these downstream nodes forms a branch of the
multicast distribution tree.
You can configure the maximum number of downstream nodes (the maximum number of outgoing
interfaces) for a single entry in the multicast forwarding table to lessen the 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, the multicast routing protocols that are running on the router will delete
them. The router will no longer add new multicast forwarding entries for newly added downstream nodes
until the number of existing downstream nodes comes down under the configured value.
Configuring the multicast forwarding table size for the public network
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the maximum
number of entries in the
multicast forwarding table.
multicast forwarding-table
route-limit limit
Optional.
The default upper limit depends on
the system operating mode.
For more information, see
Fundamentals Configuration Guide.
3. Configure the maximum
number of downstream nodes
for a single multicast
forwarding entry.
multicast forwarding-table
downstream-limit limit Optional.
256 by default.
Configuring the multicast forwarding table size in a VPN instance
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter VPN instance view. ip vpn-instance vpn-instance-name N/A
3. Configure the maximum
number of entries in the
multicast forwarding table.
multicast forwarding-table
route-limit limit Optional.
1024 by default.
4. Configure the maximum
number of downstream nodes
for a single route in the
multicast forwarding table.
multicast forwarding-table
downstream-limit limit Optional.
256 by default.
Configuring static multicast MAC address entries
In Layer-2 multicast, a Layer 2 multicast protocol (such as IGMP snooping) can dynamically add multicast
MAC address entries. Or, you can manually configure multicast MAC address entries.
Configuration guidelines
• Any legal multicast MAC address except 0100-5Exx-xxxx (where x represents a hexadecimal
number from 0 to F) can be manually added to the multicast MAC address table. Multicast MAC
addresses are the MAC addresses in which the least significant bit of the most significant octet is 1.