3Com Switch 4800G 24-Port Configuration Manual page 656

656 C 47: PIM C
HAPTER ONFIGURATION
Configuring PIM
Common Timers
Configuring hello options on an interface
Follow these steps to configure hello options on an interface:
To do...
Enter system view
Enter interface view
Configure the priority for DR
election
Configure PIM neighbor
timeout time
Configure the prune delay
time (LAN-delay)
Configure the prune override
interval
Disable join suppression
Configure the interface to
reject hello messages without
a generation ID
PIM routers discover PIM neighbors and maintain PIM neighboring relationships
with other routers by periodically sending out hello messages.
Upon receiving a hello message, a PIM router waits a random period, which is
equal to or smaller than the maximum delay between hello messages, before
sending out a hello message. This avoids collisions that occur when multiple PIM
routers send hello messages simultaneously.
Any router that has lost assert election will prune its downstream interface and
maintain the assert state for a period of time. When the assert state times out, the
assert losers will resume multicast forwarding.
A PIM router periodically sends join/prune messages to its upstream for state
update. A join/prune message contains the join/prune timeout time. The upstream
router sets a join/prune timeout timer for each pruned downstream interface, and
resumes the forwarding state of the pruned interface when this timer times out.
When a router fails to receive subsequent multicast data from the multicast source
S, the router will not immediately delete the corresponding (S, G) entries; instead,
it maintains (S, G) entries for a period of time, namely the multicast source
lifetime, before deleting the (S, G) entries.
Configuring PIM common timers globally
Follow these steps to configure PIM common timers globally:
To do...
Enter system view
Use the command...
system-view
interface interface-type
interface-number
pim hello-option dr-priority
priority
pim hello-option holdtime
interval
pim hello-option lan-delay
interval
pim hello-option
override-interval interval
pim hello-option
neighbor-tracking
pim require-genid
Use the command...
system-view
Remarks
-
-
Optional
1 by default
Optional
105 seconds by default
Optional
500 milliseconds by default
Optional
2,500 milliseconds by default
Optional
Enabled by default
Optional
By default, hello messages
without Generation_ID are
accepted
Remarks
-