Modifying PIM Global Options
Many PIM options can be modified from
their default values in global configuration mode.
PIM global parameters come with preset values. The defaults work well in most networks, but you can modify the following parameters if necessary:
- Neighbor timeout: Neighbor timeout is the interval after which a PIM device will consider a neighbor to be absent. Absence of PIM hello messages from a neighboring device indicates that a neighbor is not present.
- Hello timer: The hello timer defines the interval at which periodic hellos are sent out PIM interfaces. Devices use hello messages to inform neighboring devices of their presence.
- Prune timer: The prune timer defines how long a PIM device will maintain a prune state for a forwarding entry. The first received multicast packet is forwarded to all other PIM interfaces on the device. If there is no presence of groups on that interface, the leaf node sends a prune message upstream and stores a prune state. This prune state travels up the tree and installs a prune state. A prune state is maintained until the prune timer expires or a graft message is received for the forwarding entry.
- Prune wait timer: The prune wait timer allows you to configure the amount of time a PIM device will wait before stopping traffic to neighbor devices that do not want the traffic. A prune wait value of zero causes the PIM device to stop traffic immediately upon receiving a prune message. If there are two or more neighbors on the physical port, then the prune wait timer must not be used because one neighbor may send a prune message while the other sends a join message at the same time, or within less than three seconds.
- Graft retransmit timer: The graft retransmit timer defines the interval between the transmission of graft messages. A graft message is sent by a device to cancel a prune state. When a device receives a graft message, the device responds with a Graft Ack (acknowledge) message. If this Graft Ack message is lost, the device that sent the graft message will resend it.
- Inactivity timer: The device deletes a forwarding entry if the entry is not used to send multicast packets. The PIM inactivity timer defines how long a forwarding entry can remain unused before the device deletes it.
- Enter global configuration mode.
- Enable PIM globally.
- Apply a PIM neighbor timeout value of 360 seconds to all ports on the device operating
with PIM.
The timeout interval can be set from 3 through 65535 seconds, and it must not be less than 3.5 times the hello timer value. The default value is 105.
- Apply a PIM hello timer of 120 seconds to all ports on the device operating with PIM.
The hello timer interval can be set from 10 through 3600 seconds, and the default is 30.
- Set the PIM prune timer to 90.
The prune timer range is from 60 through 3600 seconds. The default is 180.
- Set the prune wait time to zero.
- Set the graft retransmit timer to 90 seconds.
The graft retransmit timer range is from 60 through 3600 second. The default is 180.
- Apply a PIM inactivity timer of 90 seconds to all PIM interfaces.
The value of the inactivity timer can be set from 60 through 3600 seconds. The default is 180.
The following example shows how to configure the various PIM global options.
device# configure terminal device(config)# router pim device(config-pim-router)# nbr-timeout 360 device(config-pim-router)# hello-timer 120 device(config-pim-router)# prune-timer 90 device(config-pim-router)# prune-wait 0 device(config-pim-router)# graft retransmit-timer 90 device(config-pim-router)# inactivity-timer 90