Dell PowerConnect B-RX Configuration Manual page 1318

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IPv6 PIM sparse
Changing the Shortest Path Tree (SPT) threshold
In a typical IPv6 PIM Sparse domain, there may be two or more paths from a DR (designated router)
for a multicast source to an IPv6 PIM group receiver.
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By default, the device switches from the RP to the SPT after receiving the first packet for a given
IPv6 PIM Sparse group. The BigIron RX maintains a separate counter for each IPv6 PIM Sparse
source-group pair.
You can change the number of packets that the BigIron RX receives using the RP before switching
to using the SPT.
To change the number of packets the BigIron RX receives using the RP before switching to the SPT,
enter commands such as the following.
BigIron RX(config)# ipv6 router pim
BigIron RX(config-ipv6-pim-router)# spt-threshold 1000
Syntax: [no] spt-threshold infinity | <num>
The infinity | <num> parameter specifies the number of packets. If you specify infinity, the BigIron
RX sends packets using the RP indefinitely and does not switch over to the SPT. If you enter a
specific number of packets, the BigIron RX does not switch over to using the SPT until it has sent
the number of packets you specify using the RP.
Setting the RP advertisement interval
To specify how frequently the candidate RP configured on the BigIron RX sends candidate RP
advertisement messages to the BSR, enter commands such as the following.
BigIron RX(config)# ipv6 router pim
BigIron RX(config-ipv6-pim-router)# rp-adv-interval 180
Changed RP ADV interval to 180 seconds.
Syntax: rp-adv-interval <seconds>
The <seconds > parameter specifies the number of seconds. The default is 60 seconds.
Changing the PIM join and prune message interval
By default, the BigIron RX sends PIM Sparse Join/Prune messages every 60 seconds. These
messages inform other PIM Sparse routers about clients who want to become receivers (Join) or
stop being receivers (Prune) for PIM Sparse groups.
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Path through the RP – This is the path the BigIron RX uses the first time it receives traffic for an
IPv6 PIM group. However, the path through the RP may not be the shortest path from the
BigIron RX to the receiver.
Shortest Path – Each IPv6 PIM Sparse router ithat is a DR for an IPv6 receiver calculates a
short path tree (SPT) towards the source of the IPv6 multicast traffic. The first time a BigIron
RX that is configured as an IPv6 PIM router receives a packet for an IPv6 group, it sends the
packet to the RP for hat group, which in turn will forward it to all the intended DRs that have
registered with the RP. The first time a BigIron RX that is a recipient receives a packet for an
IPv6 group, it evaluates the shortest path to the source and initiates a switch over to the SPT.
Once the BigIron RX starts receiving data on the SPT, the BigIron RX will proceed to prune itself
from the RPT.
BigIron RX Series Configuration Guide
53-1001810-01