78
NOTE:
•
The switch periodically sends a PIM hello message to PIM routers on the subnets represented by
its primary address to establish and maintain PIM neighbor relationships. The hello message
carries a list of secondary IP addresses, which is obtained and maintained by other PIM
neighbors as next hops of multicast routes. In this way, multicast packets can be forwarded to the
subnets represented by secondary IP addresses.
•
For more information about primary and secondary IP addresses, see
Layer 3—IP Services
Configuration Guide
.
Enabling IP multicast routing
Before you configure any Layer 3 multicast functionality, enable IP multicast routing first.
Enabling IP multicast routing for the public network
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable IP multicast routing.
multicast routing-enable
Disabled by default.
Enabling IP multicast routing in a VPN instance
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create a VPN instance and
enter VPN instance view.
ip vpn-instance
vpn-instance-name
N/A
3.
Configure a route
distinguisher (RD) for the
VPN instance.
route-distinguisher
route-distinguisher
No RD is configured by default.
4.
Enable IP multicast routing.
multicast routing-enable
Disabled by default.
For more information about the
ip vpn-instance
and
route-distinguisher
commands, see
MPLS
Command Reference.
Configuring multicast routing and forwarding
This section describes how to configure multicast routing and forwarding.
Configuration prerequisites
Before you configure multicast routing and forwarding, complete the following tasks:
•
Configure a unicast routing protocol so that all devices in the domain are interoperable at the
network layer.
•
Enable PIM (PIM-DM or PIM-SM).
•
Determine the maximum number of downstream nodes for a single multicast forwarding table
entry.
•
Determine the maximum number of entries in the multicast forwarding table.