3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring IPv6 PIM-DM 683
Configuring State
Refresh Parameters
To avoid the resource-consuming reflooding of unwanted traffic caused by
timeout of pruned interfaces, the device directly connected with the IPv6 multicast
source periodically sends (S, G) state refresh messages, which are forwarded hop
by hop along the initial flooding path of the IPv6 PIM-DM domain, to refresh the
prune timer state of all the devices on the path.
A device may receive multiple state refresh messages within a short time, of which
some may be duplicated messages. To keep device from receiving such duplicated
messages, you can configure the time the device must wait before receiving the
next state refresh message. If a new state refresh message is received within the
waiting time, the device will discard it; if this timer times out, the device will accept
a new state refresh message, refresh its own IPv6 PIM state, and reset the waiting
timer.
The TTL value of a state refresh message decrements by 1 whenever it passes a
device 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.
Follow these steps to configure state refresh parameters:
Configuring IPv6
PIM-DM Graft Retry
Period
In IPv6 PIM-DM, graft is the only type of message that uses the acknowledgment
mechanism. In an IPv6 PIM-DM domain, if a device does not receive a graft-ack
message from the upstream device within the specified time after it sends a graft
message, the device keeps sending new graft messages at a configurable interval,
namely graft retry period, until it receives a graft-ack from the upstream device.
Follow these steps to configure IPv6 PIM-DM graft retry period:
Enable state refresh pim ipv6
state-refresh-capable
Optional
Enabled by default
To do... Use the command... Remarks
To do... Use the command... Remarks
Enter system view system-view -
Enter IPv6 PIM view pim ipv6 -
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
To do... Use the command... Remarks
Enter system view system-view -
Enter VLAN interface view interface interface-type
interface-number
-