H3C Technologies H3C S12500-X Series Switches - Manual (Page 83)

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Step Command Remarks
1. Enter system view. system-view N/A
2. Enable IP multicast routing
and enter MRIB view.
multicast routing [ vpn-instance
vpn-instance-name ] By default, IP multicast routing is
disabled.
3. Return to system view. quit N/A
4. Enter interface view.
interface interface-type
interface-number
N/A
5. Enable PIM-DM. pim dm By default, PIM-DM is disabled.
Enabling the state refresh feature
Pruned interfaces resume multicast forwarding when the pruned state times out. To prevent this, the router
with the multicast source attached periodically sends an (S, G) state refresh message, which is forwarded
hop by hop along the initial multicast flooding path of the PIM-DM domain, to refresh the prune timer
state of all the routers on the path. A shared-media subnet can have the state refresh feature only if the
state refresh feature is enabled on all PIM routers on the subnet.
To enable the state refresh feature on all routers in PIM-DM domain:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Enable the state refresh
feature.
pim state-refresh-capable
By default, the state refresh
feature is enabled.
Configuring state refresh parameters
The router directly connected with the multicast source periodically sends state refresh messages. You can
configure the interval for sending such messages on that router.
A router might receive duplicate state refresh messages within a short time. To prevent this situation, you
can configure the amount of time that the router must wait before it receives next state refresh message.
If the router receives a new state refresh message within the specified waiting time, it discards the
message. If this timer times out, the router accepts a new state refresh message, refreshes its own PIM-DM
state, and resets the waiting timer.
The TTL value of a state refresh message decrements by 1 whenever it passes a router before it is
forwarded to the downstream node until the TTL value comes down to 0. In a small network, a state
refresh message might cycle in the network. To effectively control the propagation scope of state refresh
messages, configure an appropriate TTL value based on the network size on the router directly connected
with the multicast source.
To configure state refresh parameters:
Step Command Remarks
1. Enter system view. system-view N/A