LevelOne GTL-2691 User Manual

Page 731

HAPTER

| Multicast Routing

Configuring PIMv6 for IPv6

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command effectively prompts any downstream neighbors with hosts

receiving the flow to reply with a Join message. If no join messages are

received after the prune delay expires, this router will prune the flow.
The sum of the Override Interval and Propagation Delay are used to

calculate the LAN prune delay.

◆

Override Interval – The time required for a downstream router to

respond to a LAN Prune Delay message by sending back a Join

message if it wants to continue receiving the flow referenced in the

message. (Range: 500-6000 milliseconds; Default: 2500 milliseconds)
The override interval and the propagation delay are used to calculate

the LAN prune delay. If a downstream router has group members which
want to continue receiving the flow referenced in a LAN prune delay

message, then the override interval represents the time required for

the downstream router to process the message and then respond by

sending a Join message back to the upstream router to ensure that the

flow is not terminated.

◆

Propagation Delay – The time required for a LAN prune delay

message to reach downstream routers. (Range: 100-5000

milliseconds; Default: 500 milliseconds)
The override interval and pro po gat ion delay are used to calculate the

LAN prune delay. If a downstream router has group members which

want to continue receiving the flow referenced in a LAN prune delay

message, then the propagation delay represents the time required for

the LAN prune delay message to be propagated down from the

upstream router to all downstream routers attached to the same VLAN

interface.

◆

Trigger Hello Delay – The maximum time before transmitting a

triggered PIM Hello message after the router is rebooted or PIM is

enabled on an interface. (Range: 0-5 seconds; Default: 5 seconds)
When a router first starts or PIM is enabled on an interface, the hello

delay is set to random value between 0 and the trigger hello delay. This

prevents synchronization of Hello messages on multi-access links if

multiple routers are powered on simultaneously.
Also, if a Hello message is received from a new neighbor, the receiving

router will send its own Hello message after a random delay between 0

and the trigger hello delay.

Dense-Mode Attributes

◆

Graft Retry Interval – The time to wait for a Graft acknowledgement

before resending a Graft message. (Range: 1-10 seconds; Default: 3

seconds)
A graft message is sent by a router to cancel a prune state. When a

router receives a graft message, it must respond with an graft

acknowledgement message. If this acknowledgement message is lost,

the router that sent the graft message will resend it a number of times

(as defined by Max. Graft Retries).