3Com S7902E, Configuration Manual

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A router may receive multiple state-refresh messages within a short time, of which some may be
duplicated messages. To keep a router from receiving such duplicated messages, you can configure
the time the router must wait before receiving the next state-refresh message. If a new state-refresh
message is received within the waiting time, the router will discard it; if this timer times out, the router
will accept a new state-refresh message, refresh its own PIM-DM state, and reset 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 may cycle in the network. To effectively control the propagation scope of
state-refresh messages, you need to configure an appropriate TTL value based on the network size.
It is recommended to perform the following configurations on all routers in the PIM domain.
Follow these steps to configure state-refresh parameters:
To do... Use the command... Remarks
Enter system view
system-view
—
Enter public instance PIM view or
VPN instance PIM view pim [ vpn-instance
vpn-instance-name ]
—
Configure the interval between
state-refresh messages state-refresh-interval
interval
Optional
60 seconds by default
Configure the time to wait before
receiving a new state-refresh
message
state-refresh-rate-limit
interval
Optional
30 seconds by default
Configure the TTL value of
state-refresh messages
state-refresh-ttl ttl-value
Optional
255 by default
Configuring PIM-DM Graft Retry Period
In PIM-DM, graft is the only type of message that uses the acknowledgment mechanism. In a PIM-DM
domain, if a router does not receive a graft-ack message from the upstream router within the specified
time after it sends a graft message, the router keeps sending new graft messages at a configurable
interval, namely graft retry period, until it receives a graft-ack from the upstream router.
Follow these steps to configure graft retry period:
To do... Use the command... Remarks
Enter system view system-view —
Enter interface view
interface interface-type
interface-number
—
Configure graft retry period pim timer graft-retry interval
Optional
3 seconds by default
For the configuration of other timers in PIM-DM, refer to Configuring PIM Common Timers .