Cisco Nexus 5600 Series - Page 348

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Cisco Nexus 5600 Series NX-OS Multicast Routing Command Reference
OL-31626-01
Chapter I Commands
ip pim pre-build-spt
ip pim pre-build-spt
To prebuild the shortest path tree (SPT) for all known (S,G) in the routing table by triggering Protocol
Independent Multicast (PIM) joins upstream, use the ip pim pre-build-spt command. To reset to the
default, use the no form of this command.
ip pim pre-build-spt
no ip pim pre-build-spt
Syntax Description This command has no arguments or keywords.
Command Default Joins are triggered only if the OIF list is not empty.
Command Modes VRF configuration mode
Supported User Roles network-admin
vdc-admin
Command History
Usage Guidelines To prebuild the SPT for all known (S,G)s in the routing table by triggering PIM joins upstream, even in
the absence of any receivers, use the ip pim pre-build-spt command.
By default, PIM (S,G) joins are triggered upstream only if the OIF-list for the (S,G) is not empty. It is
useful in certain scenarios—for example, on the virtual port-channel (vPC) nonforwarding router—to
prebuild the SPTs and maintain the (S,G) states even when the system is not forwarding on these routes.
Prebuilding the SPT ensures faster convergence when a vPC failover occurs.
When you are running virtual port channels (vPCs), enabling this feature causes both vPC peer switches
to join the SPT, even though only one vPC peer switch actually routes the multicast traffic into the vPC
domain. This behavior results in the multicast traffic passing over two parallel paths from the source to
the vPC switch pair, consuming bandwidth on both paths. Additionally, when both vPC peer switches
join the SPT, one or more upstream devices in the network may be required to perform additional
multicast replications to deliver the traffic on both parallel paths toward the receivers in the vPC domain.
This command requires the LAN Base Services license.
Examples This example shows how to prebuild the SPT in the absence of receivers:
switch(config)# vrf context Enterprise
switch(config-vrf)# ip pim pre-build-spt
switch(config-vrf)#
Release Modification
6.0(2)N1(1) This command was introduced.