KB.15.15

interval causes it to stop transmitting multicast traffic onto the VLAN sooner, resulting

in less unnecessary bandwidth usage.

Changing the maximum time in seconds before the routing switch actually transmits

the initial PIM hello message on the current VLAN

Syntax:

ip pim-dense [hello-delay 0-5]

vlan [vid]ip pim-dense [hello-delay 0-5]

Changes the maximum time in seconds before the routing switch actually transmits

the initial PIM hello message on the current VLAN. In cases where a new VLAN

activates with connections to multiple routers, if all of the connected routers sent

hello packets at the same time, the receiving router could become momentarily

overloaded. This value randomizes the transmission delay to a time between 0 and

the hello delay setting. Using 0 means no delay.

After the routing switch sends the initial hello packet to a newly detected VLAN

interface, it sends subsequent hello packets according to the current hello interval

setting.

NOTE: Not used with the [no] form of the ip pim-dense command.

Default: 5 seconds

Changing the interval the routing switch waits for the graft ack from another router

before resending the graft request

Syntax:

ip pim-dense [graft-retry-interval[1-10]]

vlan[vid]ip pim-dense [graft-retry-interval[1-10]]

Graft packets result when a downstream router transmits a request to join a flow.

The upstream router responds with a graft acknowledgment packet. If the graft ack

(acknowledgement) is not received within the time period of the graft-retry-interval,

it resends the graft packet. The command [graft-retry-interval[1-10]]

changes the interval (in seconds) the routing switch waits for the graft ack from

another router before resending the graft request.

NOTE: Not used with the [no] form of the ip pim-dense command.

Default: 3 seconds

Changing the number of times the routing switch retries sending the same graft packet

to join a flow

Syntax:

ip pim-dense [max-graft-retries[1-10]]

vlan[vid]ip pim-dense [max-graft-retries[1-10]]

Changes to the number of times the routing switch will retry sending the same graft

packet to join a flow. If a graft ack response is not received after the specified

number of retries, the routing switch ceases trying to join the flow. In this case the

flow is removed until either a state-refresh from upstream re-initiates the flow or an

upstream router floods the flow.

Increasing this value helps to improve multicast reliability.

PIM VLAN (interface) configuration context 41