LevelOne GTL-2691 User Manual

Page 732

HAPTER

| Multicast Routing

Configuring PIMv6 for IPv6

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Max. Graft Retries – The maximum number of times to resend a Graft

message if it has not been acknowledged. (Range: 1-10; Default: 3)

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State Refresh Origination Interval – The interval between sending

PIM-DM state refresh control messages. (Range: 1-100 seconds;

Default: 60 seconds)
The pruned state times out approximately every three minutes and the

entire PIM-DM network is re-flooded with multicast packets and prune

messages. The state refresh feature keeps the pruned state from

timing out by periodically forwarding a control message down the

distribution tree, refreshing the prune state on the outgoing interfaces

of each router in the tree. This also enables PIM routers to recognize

topology changes (sources joining or leaving a multicast group) before
the default three-minute state timeout expires.
This command is only effectively for interfaces of first hop, PIM-DM

routers that are directly connected to the sources of multicast groups.

Sparse-Mode Attributes

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DR Priority – Sets the priority advertised by a router when bidding to

become the Designated Router (DR). (Range: 0-4294967294;

Default: 1)
More than one PIM-SM router may be connected to an Ethernet or

other shared-media LAN. If multicast hosts are directly connected to

the LAN, then only one of these routers is elected as the DR, and acts

on behalf of these hosts, sending periodic Join/Prune messages toward

a group-specific RP for each group. A single DR is elected per interface

(LAN or otherwise) using a simple election process.
The router with the highest priority configured on an interface is elected

as the DR. If more than one router attached to this interface uses the

same priority, then the router with the highest IP address is elected to

serve as the DR.
If a router does not advertise a priority in its hello messages, it is

assumed to have the highest priority and is elected as the DR. If more

than one router is not advertising its priority, then the router with the

highest IP address is elected to serve as the DR.

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Join/Prune Interval – Sets the interval at which join/prune messages

are sent. (Range: 1-65535 seconds; Default: 60 seconds)
By default, the switch sends join/prune messages every 60 seconds to

inform other PIM-SM routers about clients who want to join or leave a

multicast group.
Use the same join/prune message interval on all PIM-SM routers in the

same PIM-SM domain, otherwise the routing protocol’s performance

will be adversely affected.
The multicast interface that first receives a multicast stream from a

particular source forwards this traffic only to those interfaces on the

router that have requests to join this group. When there are no longer

any requesting groups on that interface, the leaf node sends a prune

message upstream and enters a prune state for this multicast stream.

The protocol maintains both the current join state and the pending RPT