Cisco Catalyst 2960-XR Configuration Guides

Delaying the Use of PIM Shortest-Path Tree
The change from shared to source tree happens when the first data packet arrives at the last-hop router. This
change occurs because the ip pim spt-threshold global configuration command controls that timing.
The shortest-path tree requires more memory than the shared tree but reduces delay. You might want to
postpone its use. Instead of allowing the leaf router to immediately move to the shortest-path tree, you can
specify that the traffic must first reach a threshold.
You can configure when a PIM leaf router should join the shortest-path tree for a specified group. If a source
sends at a rate greater than or equal to the specified kbps rate, the multilayer switch triggers a PIM join message
toward the source to construct a source tree (shortest-path tree). If the traffic rate from the source drops below
the threshold value, the leaf router switches back to the shared tree and sends a prune message toward the
source.
You can specify to which groups the shortest-path tree threshold applies by using a group list (a standard
access list). If a value of 0 is specified or if the group list is not used, the threshold applies to all groups.
This procedure is optional.
SUMMARY STEPS
1.
configure terminal
2.
access-list access-list-number {deny | permit} source [source-wildcard]
3.
ip pim spt-threshold {kbps | infinity} [group-list access-list-number]
4.
end
5.
show running-config
6.
copy running-config startup-config
DETAILED STEPS
PurposeCommand or Action
Enters global configuration mode.configure terminal
Example:
Switch# configure terminal
Step 1
Creates a standard access list.
access-list access-list-number {deny |
permit} source [source-wildcard]
Step 2
•
For access-list-number, the range is 1 to 99.
Example:
Switch(config)# access-list 16 permit
•
The deny keyword denies access if the conditions are matched.
•
The permit keyword permits access if the conditions are matched.
225.0.0.0 0.255.255.255
•
For source, specify the multicast group to which the threshold will
apply.
Catalyst 2960-XR Switch IP Multicast Routing Configuration Guide, Cisco IOS Release 15.0(2)EX1
66 OL-29426-01
Configuring PIM
Delaying the Use of PIM Shortest-Path Tree

Cisco Catalyst 2960-XR Specifications

General

Stacking Bandwidth	80 Gbps
Layer Support	Layer 2 and Layer 3
Jumbo Frame Support	9198 bytes
RAM	512 MB
Input Voltage	100-240V AC
Model	Catalyst 2960-XR
Uplink Interfaces	4 x 1G SFP or 2 x 10G SFP+
Downlink Interfaces	24 or 48 x Gigabit Ethernet ports
Power Supply	Internal
MAC Address Table Size	16, 000 entries
PoE	Available on PoE models
Weight	4.5 kg
Features	energy efficiency
Stacking	Up to 8 switches
Operating Temperature	0 to 45°C