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.
  1. Enter global configuration mode. 
    device# configure terminal
  2. Enable PIM globally. 
    device(config)# router pim
  3. Apply a PIM neighbor timeout value of 360 seconds to all ports on the device operating with PIM. 
    device(config-pim-router)# nbr-timeout 360
    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.
  4. Apply a PIM hello timer of 120 seconds to all ports on the device operating with PIM. 
    device(config-pim-router)# hello-timer 120
    The hello timer interval can be set from 10 through 3600 seconds, and the default is 30.
  5. Set the PIM prune timer to 90. 
    device(config-pim-router)# prune-timer 90
    The prune timer range is from 60 through 3600 seconds. The default is 180.
  6. Set the prune wait time to zero. 
    device(config-pim-router)# prune-wait 0
    The prune wait value can be set from 0 through 30 seconds. A smaller prune wait value reduces flooding of unwanted traffic. The default is 3. To view the currently configured prune wait time, enter the show ip pim dense command.
  7. Set the graft retransmit timer to 90 seconds. 
    device(config-pim-router)# graft retransmit-timer 90
    The graft retransmit timer range is from 60 through 3600 second. The default is 180.
  8. Apply a PIM inactivity timer of 90 seconds to all PIM interfaces. 
    device(config-pim-router)# inactivity-timer 90
    The value of the inactivity timer can be set from 60 through 3600 seconds. The default is 180.
  9. Configure the register probe time.
    device(config-pim-router)# register-probe-time 15
  10. Configure the register suppression time.
    device(config-pim-router)# register-suppress-time 90
  11. Configure the message interval.
    device(config-pim-router)# message-interval 120
  12. Configure the SPT threshold.
    device(config-pim-router)# spt-threshold 10

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
device(config-pim-router)# register-probe-time 15
device(config-pim-router)# register-suppress-time 90
device(config-pim-router)# message-interval 120
device(config-pim-router)# spt-threshold 10
Parent topic: PIM Dense