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Table Of Contents
Related Features and Technologies
Supported Standards, MIBs, and RFCs
Verifying PIM Dense Mode State Refresh Configuration
Monitoring and Maintaining PIM DM State Refresh
ip pim state-refresh origination-interval
PIM Dense Mode State Refresh
This feature module describes the Protocol Independent Multicast (PIM) Dense Mode (DM) State Refresh feature, which is an extension to the dense operational mode of the PIM Version 2 multicast routing architecture. This feature module includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
PIM dense mode builds source-based multicast distribution trees that operate on a flood and prune principle. Multicast packets from a source are flooded to all areas of a PIM dense mode network. PIM routers that receive multicast packets and have no directly connected multicast group members or PIM neighbors send a prune message back up the source-based distribution tree toward the source of the packets. As a result, subsequent multicast packets are not flooded to pruned branches of the distribution tree. However, the pruned state in PIM dense mode times out approximately every 3 minutes and the entire PIM dense mode network is reflooded with multicast packets and prune messages. This reflooding of unwanted traffic throughout the PIM dense mode network consumes network bandwidth.
The PIM Dense Mode State Refresh feature keeps the pruned state in PIM dense mode from timing out by periodically forwarding a control message down the source-based distribution tree. The control message refreshes the prune state on the outgoing interfaces of each router in the distribution tree.
Benefits
The PIM Dense Mode State Refresh feature keeps the pruned state in PIM dense mode from timing out, which saves network bandwidth by greatly reducing the reflooding of unwanted multicast traffic to pruned branches of the PIM dense mode network. This feature also enables PIM routers in a PIM dense mode multicast network to recognize topology changes (sources joining or leaving a multicast group) before the default 3-minute state refresh timeout period.
Restrictions
All routers in a PIM dense mode network must run a Cisco IOS software release, such as Cisco IOS Release 12.1(5)T, that supports the PIM Dense Mode State Refresh feature to process and forward state refresh control messages.
The origination interval for the state refresh control message must be the same for all PIM routers on the same LAN. Specifically, the same origination interval must be configured on each router interface that is directly connected to the LAN.
Related Features and Technologies
The PIM Dense Mode State Refresh feature is an extension of the PIM Version 2 multicast routing architecture, which is documented in the Release 12.1 Cisco IOS IP and IP Routing Configuration Guide and the Cisco IOS IP and IP Routing Command Reference.
Supported Platforms
The PIM Dense Mode State Refresh feature is supported on the following platforms:
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Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of MIBs supported by platform and Cisco IOS releases, and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
You must have PIM dense mode enabled on an interface before configuring the PIM Dense Mode State Refresh feature.
Configuration Tasks
There are no configuration tasks for enabling the PIM Dense Mode State Refresh feature. By default, all PIM routers that are running a Cisco IOS software release that supports the PIM Dense Mode State Refresh feature automatically process and forward state refresh control messages. To disable the processing and forwarding of state refresh control messages on a PIM router, use the ip pim state-refresh disable global configuration command.
The origination of state refresh control messages is disabled by default. To configure the origination of the control messages on a PIM router, use the following commands beginning in global configuration mode:
Verifying PIM Dense Mode State Refresh Configuration
Use the show ip pim interface [type number] detail and the show ip pim neighbor [interface] commands to verify that the PIM Dense Mode State Refresh feature is configured correctly. The following output of the show ip pim interface [type number] detail command indicates that processing, forwarding, and origination of state refresh control messages is enabled.
Router# show ip pim interface fastethernet 0/1 detailFastEthernet0/1 is up, line protocol is upInternet address is 172.16.8.1/24Multicast switching:processMulticast packets in/out:0/0Multicast boundary:not setMulticast TTL threshold:0PIM:enabledPIM version:2, mode:densePIM DR:172.16.8.1 (this system)PIM neighbor count:0PIM Hello/Query interval:30 secondsPIM State-Refresh processing:enabled
The S in the Mode field of the following show ip pim neighbor [interface] command output indicates that the neighbor has the PIM Dense Mode State Refresh feature configured.
Router# show ip pim neighborPIM Neighbor TableNeighbor Interface Uptime/Expires Ver DRAddress Priority/ModeMonitoring and Maintaining PIM DM State Refresh
Following are the PIM Dense Mode State Refresh control messages that are sent and received by a PIM router after the debug ip pim privileged EXEC command is configured for multicast group 239.0.0.1:
Router# debug ip pim 239.0.0.1*Mar 1 00:25:10.416:PIM:Originating refresh message for(172.16.8.3,239.0.0.1)*Mar 1 00:25:10.416:PIM:Send SR on Ethernet1/1 for (172.16.8.3,239.0.0.1)TTL=9The following output from the show ip mroute command displays are the resulting prune timer changes for interface Ethernet 1/0 and multicast group 239.0.0.1. (The following output assumes that the debug ip pim privileged EXEC command has already been configured on the router.) In the first output from the show ip mroute command, the prune timer reads 00:02:06. The debug messages indicate that a PIM Dense Mode State Refresh control message is received and sent on Ethernet interface 1/0, and that other PIM Dense Mode State Refresh routers were discovered. In the second output from the show ip mroute command, the prune timer has been reset to 00:02:55.
Router# show ip mroute 239.0.0.1(172.16.8.3, 239.0.0.1), 00:09:50/00:02:06, flags:PTIncoming interface:Ethernet1/1, RPF nbr 172.16.5.2Outgoing interface list:Configuration Examples
The following example is for a PIM router that is originating, processing, and forwarding PIM Dense Mode State Refresh control messages on Fast Ethernet interface 0/1 every 60 seconds:
ip multicast-routinginterface FastEthernet0/1ip address 172.16.8.1 255.255.255.0ip pim state-refresh origination-interval 60ip pim dense-modeThe following example is for a PIM router that is just processing and forwarding PIM Dense Mode State Refresh control messages on Fast Ethernet interface 1/1:
ip multicast-routinginterface FastEthernet1/1ip address 172.16.7.3 255.255.255.0ip pim dense-modeCommand Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.
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ip pim state-refresh disable
To disable the processing and forwarding of Protocol Independent Multicast (PIM) Dense Mode State Refresh feature control messages on a PIM router, use the ip pim state-refresh disable global configuration command. To reenable the processing and forwarding of PIM Dense Mode State Refresh control messages, use the no form of this command.
ip pim state-refresh disable
no ip pim state-refresh disable
Syntax Description
This command has no arguments or keywords.
Defaults
The processing and forwarding of PIM Dense Mode State Refresh control messages is enabled on PIM routers that are running a Cisco IOS software release that supports the PIM Dense Mode State Refresh feature.
Command Modes
Global configuration
Command History
Usage Guidelines
Configuring this command removes PIM Dense Mode State Refresh information from PIM hello messages.
Examples
The following example disables the periodic forwarding of the PIM Dense Mode State Refresh control message down a source-based IP multicast distribution tree:
ip pim state-refresh disableRelated Commands
ip pim state-refresh origination-interval
To configure the origination of and the interval for the Protocol Independent Multicast (PIM) Dense Mode State Refresh feature control messages on a PIM router, use the ip pim state-refresh origination-interval interface configuration command. To stop the origination of the PIM Dense Mode State Refresh control message, use the no form of this command.
ip pim state-refresh origination-interval [interval]
no ip pim state-refresh origination-interval
Syntax Description
interval
(Optional) The number of seconds between PIM Dense Mode State Refresh control messages. The default is 60 seconds. The available interval range is from 4 to 100 seconds.
Defaults
PIM Dense Mode State Refresh control message origination is disabled. By default, all PIM routers that are running a Cisco IOS software release that supports PIM Dense Mode State Refresh process and forward PIM Dense Mode State Refresh control messages.
Command Modes
Interface configuration
Command History
Usage Guidelines
Configure this command on the interfaces of the first hop, PIM dense mode routers that are directly connected to sources for PIM-DM multicast groups.
By default, the processing and forwarding of PIM Dense Mode State Refresh control messages is enabled on PIM routers that are running a Cisco IOS software release that supports the PIM Dense Mode State Refresh feature.
Examples
The following example configures the origination of the state refresh control message on Ethernet interface 0 of a PIM dense mode router with an interval of 80 seconds:
interface ethernet 0ip pim state-refresh origination-interval 80Related Commands
show ip pim interface
To display information about interfaces configured for Protocol Independent Multicast (PIM), use the show ip pim interface EXEC command.
show ip pim interface [type number] [count] [detail]
Syntax Description
type
(Optional) Interface type.
number
(Optional) Interface number.
count
(Optional) Number of packets received and sent out the interface.
detail
(Optional) PIM details of each interface.
Defaults
No default behavior or values.
Command Modes
EXEC
Command History
Usage Guidelines
This command works only on interfaces that are configured for PIM.
Examples
The following is sample output from the show ip pim interface command:
Router# show ip pim interfaceAddress Interface Mode Neighbor Query DRCount Interval198.92.37.6 Ethernet0 Dense 2 30 198.92.37.33198.92.36.129 Ethernet1 Dense 2 30 198.92.36.13110.1.37.2 Tunnel0 Dense 1 30 0.0.0.0The following is sample output from the show ip pim interface command with the count keyword:
Router# show ip pim interface countAddress Interface FS Mpackets In/Out171.69.121.35 Ethernet0 * 548305239/13744856171.69.121.35 Serial0.33 * 8256/67052912198.92.12.73 Serial0.1719 * 219444/862191Table 1 describes the significant fields shown in the displays.
The following is sample output from the show ip pim interface command with the detail keyword for Fast Ethernet interface 0/1:
Router# show ip pim interface fastethernet 0/1 detailFastEthernet0/1 is up, line protocol is upInternet address is 172.16.8.1/24Multicast switching:processMulticast packets in/out:0/0Multicast boundary:not setMulticast TTL threshold:0PIM:enabledPIM version:2, mode:densePIM DR:172.16.8.1 (this system)PIM neighbor count:0PIM Hello/Query interval:30 secondsTable 2 describes the significant fields shown in the display.
Related Commands