Multicast Subsecond Convergence
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Table Of Contents
Multicast Subsecond Convergence
Supported Standards, MIBs, and RFCs
Modifying the Periodic RPF Check Interval
Configuring PIM RPF Failover Intervals
Modifying the PIM Router Query Message Interval
Verifying Multicast Subsecond Convergence Configurations
Monitoring and Maintaining Multicast Subsecond Convergence
Modifying the Periodic RPF Check Interval Example
Configuring PIM RPF Failover Intervals Example
Modifying the PIM Router Query Message Interval Example
Multicast Subsecond Convergence
Feature History
This document describes the Multicast Subsecond Convergence feature in Cisco IOS Release 12.0(22)S and includes the following sections:
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Supported Standards, MIBs, and RFCs
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Feature Overview
The Multicast Subsecond Convergence feature in Cisco IOS Release 12.0(22)S comprises a comprehensive set of features and protocol enhancements that provide for improved scalability and convergence in multicast-based services. This feature set provides for the ability to scale to larger services levels and to recover multicast forwarding after service failure in subsecond time frames.
Multicast subsecond convergence allows you to send Protocol Independent Multicast (PIM) router-query messages (PIM hellos) every few milliseconds. In previous releases, you could send the PIM hellos every few seconds. By enabling a router to send PIM hello messages more often, this feature allows the router to discover unresponsive neighbors more quickly. As a result, the router can implement failover or recovery procedures more efficiently.
The Multicast Subsecond Convergence feature set enhances both enterprise and service provider network backbones by providing almost instantaneous recovery of multicast paths after unicast routing recovery. Forwarding performance is unaffected by this new feature and is comparable to previous releases of Cisco 12.0 S software.
Because PIM relies on the unicast routing table to calculate its Reverse Path Forwarding (RPF) when a change in the network topology occurs, unicast protocols first need to calculate options for the best paths for traffic, and then multicast can determine the best path.
Multicast subsecond convergence allows multicast protocol calculations to finish almost immediately after the unicast calculations are completed. As a result, multicast traffic forwarding is restored substantially faster after a topology change.
The scalability enhancements improve on the efficiency of handling increases (or decreases) in service users (receivers) and service load (sources or content). Scalability enhancements in this release include the following:
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The scalability enhancements provide the following benefits:
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Multicast subsecond convergence provides the ability to trigger a check of RPF changes for mroute states. This check is triggered by unicast routing changes. By performing a triggered RPF check, users can set the periodic RPF check to a relatively high value (for example, 10 seconds) and still fail over quickly.
The triggered RPF check enhancement reduces the time needed for service to be restored after disruption, such as for single service events (for example, in a situation with one source and one receiver) or as the service scales along any parameter (for example, many sources, many receivers, and many interfaces). This enhancement decreases in time-to-converge PIM (mroute), IGMP, and MSDP (SA cache) states.
Benefits
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Restrictions
Routers that use the subsecond DR failover enhancement need to be able to process hello interval information arriving in milliseconds. Routers that are congested or do not have enough CPU cycles to process the hello interval may assume that the PIM neighbor has gone, although this may not be the case.
Related Documents
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Supported Platforms
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Determining Platform Support Through Cisco Feature Navigator
Cisco IOS software is packaged in feature sets that are supported on specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.
Cisco Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.
To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, refer to the online release notes or, if supported, Cisco Feature Navigator.
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 locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
http://tools.cisco.com/ITDIT/MIBS/servlet/index
If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
Service providers must have a multicast-enabled core in order to use the Cisco Multicast Subsecond Convergence feature.
Configuration Tasks
See the following sections for configuration tasks for this feature. Each task in the list is identified as either required or optional.
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Modifying the Periodic RPF Check Interval
Note
To modify the intervals at which periodic RPF checks occur, use the following command in global configuration mode:
Step 1
Router(config)# ip multicast rpf interval seconds
Configures the periodic RPF check intervals to occur at a specified interval, in seconds.
Configuring PIM RPF Failover Intervals
Note
To configure the intervals at which PIM RPF failover will be triggered by changes in the routing tables, use the following command in global configuration mode:
Step 1
Router(config)# ip multicast rpf backoff minimum maximum
Configures the minimum and the maximum backoff intervals.
Modifying the PIM Router Query Message Interval
Router query messages are used to elect a PIM designated router. The designated router is responsible for sending IGMP host query messages. By default, multicast routers send PIM router query messages every 30 seconds. To modify this interval, use the following command in interface configuration mode:
Step 1
Router(config-if)# ip pim query-interval period [msec]
Configures the frequency at which multicast routers send PIM router hello messages.
Verifying Multicast Subsecond Convergence Configurations
To display detailed information about and to verify information regarding the Multicast Subsecond Convergence feature, perform the following steps:
Step 1
Router# show ip pim interface Ethernet1/0Address Interface Ver/ Nbr Query DR DRMode Count Intvl Prior172.16.1.4 Ethernet1/0 v2/S 1 100 ms 1 172.16.1.4Step 2
router# show ip pim neighborPIM Neighbor TableNeighbor Interface Uptime/Expires Ver DRAddress Prio/Mode172.16.1.3 Ethernet1/0 00:03:41/250 msec v2 1 / SStep 3
router# show ip rpf eventsLast 15 triggered multicast RPF check eventsRPF backoff delay: 500 msecRPF maximum delay: 5 secDATE/TIME BACKOFF PROTOCOL EVENT RPF CHANGESMar 7 00:17:07.244 500 msec Static Route UP 0Mar 7 00:16:55.082 500 msec BGP Route UP 0Mar 7 00:16:43.880 500 msec ISIS Route UP 0Mar 7 00:16:32.692 500 msec ISIS Route UP 0Mar 7 00:16:19.712 1000 sec Static Route UP 0Mar 7 00:16:18.212 500 msec Connected Route UP 0Mar 7 00:16:13.140 500 msec Static Route UP 0Mar 7 00:16:08.160 500 msec Connected Route UP 0
Monitoring and Maintaining Multicast Subsecond Convergence
To monitor and maintain the multicast subsecond convergence feature, use the following EXEC commands, as needed:
Configuration Examples
This section provides the following configuration examples:
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Modifying the Periodic RPF Check Interval Example
In the following example, the ip multicast rpf interval has been set to 10 seconds. This command does not show up in show running-config output unless the interval value has been configured to be the nondefault value.
Router# show running-configip subnet-zero!ip multicast-routingip multicast rpf interval 10 -- Periodic RPF check interval...interface Ethernet0/0ip address 172.16.2.1 255.255.255.0...ip pim sparse-mode!Configuring PIM RPF Failover Intervals Example
In the following example, the ip multicast rpf backoff command has been configured with a minimum backoff interval value of 100 and a maximum backoff interval value of 2500. This command does not show up in show running-config output unless the interval value has been configured to be the nondefault value.
Router# show running-configip subnet-zero!ip multicast-routing...ip multicast rpf backoff 100 2500 -- Triggered RPF backoff values.!!interface Ethernet0/0ip address 172.16.2.1 255.255.255.0...ip pim sparse-mode!Modifying the PIM Router Query Message Interval Example
In the following example, the ip pim query-interval command has been set to 100 milliseconds. This command does not show up in show running-config output unless the interval value has been configured to be the nondefault value.
Router# show running-configip subnet-zero!...interface Ethernet0/0ip address 172.16.2.1 255.255.255.0ip pim query-interval 100 msec -- PIM Hello query intervalip pim sparse-mode!Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.
New Commands
Modified Commands
debug ip mrouting
To display changes to the multicast route (mroute) table, use the debug ip mrouting command in privileged EXEC mode. To disable debugging output, use the no form of this command.
debug ip mrouting [vrf vrf-name] [rpf-events] [group]
no debug ip mrouting [vrf vrf-name] [rpf-events] [group]
Syntax Description
Defaults
No default behavior or values.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
This command indicates when the router has made changes to the mroute table. Use the debug ip pim and debug ip mrouting commands consecutively to obtain additional multicast routing information. In addition, use the debug ip igmp command to learn why an mroute message is being displayed.
This command generates a substantial amount of output. Use the optional group argument to limit the output to a single multicast group.
Examples
The following is sample output from the debug ip mrouting command:
Router# debug ip mrouting 224.2.0.1MRT: Delete (10.0.0.0/8, 224.2.0.1)MRT: Delete (10.4.0.0/16, 224.2.0.1)MRT: Delete (10.6.0.0/16, 224.2.0.1)MRT: Delete (10.9.0.0/16, 224.2.0.1)MRT: Delete (10.16.0.0/16, 224.2.0.1)MRT: Create (*, 224.2.0.1), if_input NULLMRT: Create (224.69.15.0/24, 225.2.2.4), if_input Ethernet0, RPF nbr 224.69.61.15MRT: Create (224.69.39.0/24, 225.2.2.4), if_input Ethernet1, RPF nbr 0.0.0.0MRT: Create (10.0.0.0/8, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0MRT: Create (10.4.0.0/16, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0MRT: Create (10.6.0.0/16, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0MRT: Create (10.9.0.0/16, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0MRT: Create (10.16.0.0/16, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0The following lines show that multicast IP routes were deleted from the routing table:
MRT: Delete (10.0.0.0/8, 224.2.0.1)MRT: Delete (10.4.0.0/16, 224.2.0.1)MRT: Delete (10.6.0.0/16, 224.2.0.1)The (*, G) entries are generally created by receipt of an Internet Group Management Protocol (IGMP) host report from a group member on the directly connected LAN or by a Protocol Independent Multicast (PIM) join message (in sparse mode) that this router receives from a router that is sending joins toward the RP. This router will in turn send a join toward the Route Processor (RP) that creates the shared tree (or RP tree).
MRT: Create (*, 224.2.0.1), if_input NULLThe following lines are an example of creating an (S, G) entry that shows that an IP multicast packet (mpacket) was received on Ethernet interface 0. The second line shows a route being created for a source that is on a directly connected LAN. The RPF means "reverse path forwarding," whereby the router looks up the source address of the multicast packet in the unicast routing table and determines which interface will be used to send a packet to that source.
MRT: Create (224.69.15.0/24, 225.2.2.4), if_input Ethernet0, RPF nbr 224.69.61.15MRT: Create (224.69.39.0/24, 225.2.2.4), if_input Ethernet1, RPF nbr 224.0.0.0The following lines show that multicast IP routes were added to the routing table. Note the 224.0.0.0 as the RPF, which means the route was created by a source that is directly connected to this router.
MRT: Create (10.9.0.0/16, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0MRT: Create (10.16.0.0/16, 224.2.0.1), if_input Ethernet1, RPF nbr 224.0.0.0If the source is not directly connected, the neighbor address shown in these lines will be the address of the router that forwarded the packet to this router.
The shortest path tree state maintained in routers consists of source (S), multicast address (G), outgoing interface (OIF), and incoming interface (IIF). The forwarding information is referred to as the multicast forwarding entry for (S, G).
An entry for a shared tree can match packets from any source for its associated group if the packets come through the proper incoming interface as determined by the RPF lookup. Such an entry is denoted as
(*, G). A (*, G) entry keeps the same information a (S, G) entry keeps, except that it saves the rendezvous point address in place of the source address in sparse mode or as 24.0.0.0 in dense mode.Table 2 describes the significant fields shown in the display.
Table 1 debug ip mrouting Field Descriptions
MRT
Multicast route table.
RPF
Reverse path forwarding.
nbr
Neighbor.
Related Commands
debug ip pim
To display Protocol Independent Multicast (PIM) packets received and sent, and to display PIM-related events, use the debug ip pim command in privileged EXEC mode. To disable debugging output, use the no form of this command.
debug ip pim [vrf vrf-name] [group | df [rp-address]] [hello]
no debug ip pim [vrf vrf-name] [group | df [rp-address]] [hello]
Syntax Description
Defaults
All PIM packets are displayed.
Command Modes
Privileged EXEC
Command History
10.2
This command was introduced.
12.1(2)T
The df keyword was added.
12.0(22)S
The vrf keyword, vrf-name argument, and hello keyword were added.
Usage Guidelines
PIM uses Internet Group Management Protocol (IGMP) packets to communicate with routers and advertise reachability information.
Use this command with the debug ip igmp and debug ip mrouting commands to display additional multicast routing information.
Examples
The following is sample output from the debug ip pim command:
Router# debug ip pim 224.2.0.1PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Received Join/Prune on Tunnel0 from 10.3.84.1PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Received RP-Reachable on Ethernet1 from 172.16.20.31PIM: Update RP expiration timer for 224.2.0.1PIM: Forward RP-reachability packet for 224.2.0.1 on Tunnel0PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Prune-list (10.221.196.51/32, 224.2.0.1)PIM: Set join delay timer to 2 seconds for (10.221.0.0/16, 224.2.0.1) on Ethernet1PIM: Received Join/Prune on Ethernet1 from 172.16.37.6PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Received Join/Prune on Tunnel0 from 10.3.84.1PIM: Join-list: (*, 224.2.0.1) RP 172.16.20.31PIM: Add Tunnel0 to (*, 224.2.0.1), Forward statePIM: Join-list: (10.0.0.0/8, 224.2.0.1)PIM: Add Tunnel0 to (10.0.0.0/8, 224.2.0.1), Forward statePIM: Join-list: (10.4.0.0/16, 224.2.0.1)PIM: Prune-list (172.16.84.16/28, 224.2.0.1) RP-bit set RP 172.16.84.16PIM: Send Prune on Ethernet1 to 172.16.37.6 for (172.16.84.16/28, 224.2.0.1), RPPIM: For RP, Prune-list: 10.9.0.0/16PIM: For RP, Prune-list: 10.16.0.0/16PIM: For RP, Prune-list: 10.49.0.0/16PIM: For RP, Prune-list: 10.84.0.0/16PIM: For RP, Prune-list: 10.146.0.0/16PIM: For 10.3.84.1, Join-list: 172.16.84.16/28PIM: Send periodic Join/Prune to RP via 172.16.37.6 (Ethernet1)The following lines appear periodically when PIM is running in sparse mode and indicate to this router the multicast groups and multicast sources in which other routers are interested:
PIM: Received Join/Prune on Ethernet1 from 172.16.37.33PIM: Received Join/Prune on Ethernet1 from 172.16.37.33The following lines appear when an RP message is received and the RP timer is reset. The expiration timer sets a checkpoint to make sure the RP still exists. Otherwise, a new RP must be discovered.
PIM: Received RP-Reachable on Ethernet1 from 172.16.20.31PIM: Update RP expiration timer for 224.2.0.1PIM: Forward RP-reachability packet for 224.2.0.1 on Tunnel0The prune message in the following line states that this router is not interested in the Source-Active (SA) information. This message tells an upstream router to stop forwarding multicast packets from this source.
PIM: Prune-list (10.221.196.51/32, 224.2.0.1)In the following line, a second router on the network wants to override the prune message that the upstream router just received. The timer is set at a random value so that if additional routers on the network still want to receive multicast packets for the group, only one will actually send the message. The other routers will receive the join message and then suppress sending their own message.
PIM: Set join delay timer to 2 seconds for (10.221.0.0/16, 224.2.0.1) on Ethernet1In the following line, a join message is sent toward the RP for all sources:
PIM: Join-list: (*, 224.2.0.1) RP 172.16.20.31In the following lines, the interface is being added to the outgoing interface (OIF) of the (*, G) and
(S, G) multicast route (mroute) table entry so that packets from the source will be forwarded out that particular interface:PIM: Add Tunnel0 to (*, 224.2.0.1), Forward statePIM: Add Tunnel0 to (10.0.0.0/8, 224.2.0.1), Forward stateThe following line appears in sparse mode only. There are two trees on which data may be received: the RP tree and the source tree. In dense mode there is no RP. After the source and the receiver have discovered one another at the RP, the first-hop router for the receiver will usually join to the source tree rather than the RP tree.
PIM: Prune-list (172.16.84.16/28, 224.2.0.1) RP-bit set RP 172.16.84.16The send prune message in the next line shows that a router is sending a message to a second router saying that the first router should no longer receive multicast packets for the (S, G). The RP at the end of the message indicates that the router is pruning the RP tree and is most likely joining the source tree, although the router may not have downstream members for the group or downstream routers with members of the group. The output shows the specific sources from which this router no longer wants to receive multicast messages.
PIM: Send Prune on Ethernet1 to 172.16.37.6 for (172.16.84.16/28, 224.2.0.1), RPThe following lines indicate that a prune message is sent toward the RP so that the router can join the source tree rather than the RP tree:
PIM: For RP, Prune-list: 10.9.0.0/16PIM: For RP, Prune-list: 10.16.0.0/16PIM: For RP, Prune-list: 10.49.0.0/16In the following line, a periodic message is sent toward the RP. The default period is once per minute. Prune and join messages are sent toward the RP or sourcerather than directly to the RP or source. It is the responsibility of the next hop router to take proper action with this message, such as continuing to forward it to thenext router in the tree.PIM: Send periodic Join/Prune to RP via 172.16.37.6 (Ethernet1)Table 2 describes the significant fields shown in the display.
Table 2 debug ip mcache Field Descriptions
PIM
Protocol Independent Multicast (PIM)
10.221.196.51/32
Host route with 32 bits of mask.
Related Commands
ip multicast rpf backoff
To configure the intervals at which Protocol Independent Multicast (PIM) Reverse Path Forwarding (RPF) failover will be triggered by changes in the routing tables, use the ip multicast rpf backoff command in global configuration mode. To set the triggered RPF check to the default values, use the no form of this command.
ip multicast rpf backoff minimum maximum [disable]
no ip multicast rpf backoff minimum maximum [disable]
Syntax Description
Defaults
This command is enabled by default.
Minimum backoff default is 500 ms.
Maximum backoff default is 5000 ms.
Command Modes
Global configuration
Command History
Usage Guidelines
In an unstable unicast routing environment that uses triggered RPF checks, the environment could be constantly triggering RPF checks, which places a burden on the resources of the router. To avoid this problem, the ip multicast rpf backoff command prevents a second triggered RPF check from occurring for the length of time configured. That is, the PIM "backs off" from another triggered RPF check for a minimum amount of milliseconds as configured by the user.
If the backoff period expires without further routing table changes, PIM then scans for routing changes and accordingly establishes multicast RPF changes. However, if more routing changes occur during the backoff period, PIM doubles the backoff period to avoid overloading the router with PIM RPF changes while the routing table is still converging.
Note
The maximum argument is used to configure the maximum backoff interval. The backoff time is reset to time configured by the minimum argument if an entire backoff interval has expired without routing changes.
The maximum argument default allows the RPF change behavior to be backward-compatible, allowing a 5-second RPF check interval in case of frequent route changes and a 500-ms RPF check interval in stable networks with only unplanned routing changes. In previous software releases, PIM polled the routing tables for changes every 5 seconds.
You likely do not need to change the defaults of the ip multicast rpf backoff command unless you have frequent route changes in your router (for example, on a dial-in router). Changing the defaults can allow you to reduce the maximum RPF check interval for faster availability of IP multicast on newly established routes or to increase the maximum RPF check interval to reduce the CPU load caused by the RPF check.
Examples
The following example configures the minimum backoff interval at 100 ms and the maximum backoff interval at 2500 ms:
Router(config)# ip multicast rpf backoff 100 2500
ip multicast rpf interval
To modify the intervals at which periodic Reverse Path Forwarding (RPF) checks occur, use the ip multicast rpf interval command in global configuration mode. To return to the default interval, use the no form of this command.
ip multicast rpf interval seconds [list {access-list} | route-map {route-map}]
no ip multicast rpf interval seconds [list {access-list} | route-map {route-map}]
Syntax Description
Defaults
This command is enabled by default.
The default interval value is 10 seconds.
Command Modes
Global configuration
Command History
Usage Guidelines
You can configure multiple instances of this command by using an access list or a route map.
Note
Examples
The following example sets the periodic RPF check interval to 10 seconds:
ip multicast rpf interval 10The following example sets a periodic RPF check interval of 3 seconds for groups that are defined by access list 10:
ip multicast rpf interval 3 list 10The following example sets a periodic RPF check interval of 2 seconds for groups that are defined by the route map named map:
ip multicast rpf interval 2 route-map mapRelated Commands
ip igmp query-interval
Configures the frequency at which the Cisco IOS software sends IGMP host hello messages.
ip pim query-interval
To configure the frequency of Protocol Independent Multicast (PIM) hellos, use the ip pim query-interval command in interface configuration mode. To return to the default interval, use the no form of this command.
ip pim query-interval period [msec]
no ip pim query-interval
Syntax Description
Defaults
This command is enabled by default.
The PIM hello messages are sent every 30 seconds.
Command Modes
Interface configuration
Command History
10.0
This command was introduced.
12.0(22)S
This command was updated with the msec keyword, which allows you to specify the interval between PIM hello messages in milliseconds.
Usage Guidelines
Routers configured for IP multicast send PIM hello messages to determine which router will be the designated router for each LAN segment (subnet). The designated router sends IGMP host-query messages to all hosts on the directly connected LAN. When operating in sparse mode, the designated router sends source registration messages to the Route Processor (RP). The designated router is the router with the largest IP address.
Examples
The following example changes the PIM hello interval to 45 seconds:
interface tunnel 0ip pim query-interval 45The following example changes the PIM hello interval to 100 milliseconds:
interface Ethernet1/0ip address 172.16.1.3 255.255.255.0ip pim query-interval 100 msecRelated Commands
ip igmp query-interval
Configures the frequency at which the Cisco IOS software sends IGMP host query messages.
show ip pim interface
To display information about interfaces configured for Protocol Independent Multicast (PIM), use the show ip pim interface command in EXEC mode.
show ip pim interface [type number] [df | count] [rp-address] [detail]
Syntax Description
Defaults
If no interface is specified, all interfaces are displayed.
Command Modes
EXEC
Command History
Usage Guidelines
This command works only on interfaces that are configured for PIM. Use the show ip pim interface count command to display switching counts for Multicast Distributed Switching (MDS) and other fast-switching statistics. For more information on MDS, refer to the "Configuring Multicast Distributed Switching" chapter in the Cisco IOS Release 12.0 Switching Services Configuration Guide.
Examples
The following is sample output from the show ip pim interface command:
Router# show ip pim interface Ethernet1/0Address Interface Ver/ Nbr Query DR DRMode Count Intvl Prior172.16.1.4 Ethernet1/0 v2/S 1 100 ms 1 172.16.1.4The following is sample output from the show ip pim interface command when the count keyword is specified:
Router# show ip pim interface countAddress Interface FS Mpackets In/Out172.30.121.35 Ethernet0 * 548305239/13744856172.30.121.35 Serial0.33 * 8256/67052912198.92.12.73 Serial0.1719 * 219444/862191The following are sample outputs from the show ip pim interface command when the df keyword is specified:
Router# show ip pim interface dfInterface RP DF Winner Metric UptimeEthernet3/3 10.10.0.2 10.4.0.2 0 00:03:4910.10.0.3 10.4.0.3 0 00:01:4910.10.0.5 10.4.0.4 409600 00:01:49Ethernet3/4 10.10.0.2 10.5.0.2 0 00:03:4910.10.0.3 10.5.0.2 409600 00:02:3210.10.0.5 10.5.0.2 435200 00:02:16Loopback0 10.10.0.2 10.10.0.2 0 00:03:4910.10.0.3 10.10.0.2 409600 00:02:3210.10.0.5 10.10.0.2 435200 00:02:16Router# show ip pim interface Ethernet3/3 df 10.10.0.3Designated Forwarder election for Ethernet3/3, 10.4.0.2, RP 10.10.0.3State Non-DFOffer count is 0Current DF ip address 10.4.0.3DF winner up time 00:02:33Last winner metric preference 0Last winner metric 0Table 3 describes the significant fields shown in the displays.
Related Commands
ip pim
Enables PIM on an interface.
Lists the PIM neighbors discovered by the Cisco IOS software.
show ip pim neighbor
To list the Protocol Independent Multicast (PIM) neighbors discovered by the Cisco IOS software, use the show ip pim neighbor command in EXEC mode.
show ip pim neighbor [type number]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
Use this command to determine which routers on the LAN are configured for PIM.
Examples
The following is sample output from the show ip pim neighbor command:
Router# show ip pim neighborPIM Neighbor TableNeighbor Interface Uptime/Expires Ver DRAddress Prio/Mode172.16.1.3 Ethernet1/0 00:03:41/250 msec v2 1 / STable 4 describes the significant fields shown in the display.
Related Commands
show ip rpf events
To display the last 15 triggered multicast Reverse Path Forwarding (RPF) check events, use the show ip rpf events command in EXEC mode.
show ip rpf events
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
Usage Guidelines
Use this command to determine the most recent triggered multicast RPF check events.
Examples
The following is sample output from the show ip rpf events command:
router# show ip rpf eventsLast 15 triggered multicast RPF check eventsRPF backoff delay: 500 msecRPF maximum delay: 5 secDATE/TIME BACKOFF PROTOCOL EVENT RPF CHANGESMar 7 00:17:07.244 500 msec Static Route UP 0Mar 7 00:16:55.082 500 msec BGP Route UP 0Mar 7 00:16:43.880 500 msec ISIS Route UP 0Mar 7 00:16:32.692 500 msec ISIS Route UP 0Mar 7 00:16:19.712 1000 sec Static Route UP 0Mar 7 00:16:18.212 500 msec Connected Route UP 0Mar 7 00:16:13.140 500 msec Static Route UP 0Mar 7 00:16:08.160 500 msec Connected Route UP 0The following is sample output from the show ip rpf events command when the ip multicast rpf backoff command is used with the disable keyword, disabling the triggered RPF check function:
Router# show ip rpf eventsLast 15 triggered multicast RPF check eventsNote:Triggered RPF disabled!RPF backoff delay:50 msecRPF maximum delay:2 secDATE/TIME BACKOFF PROTOCOL EVENT RPF CHANGESSep 4 06:25:31.707 500 msec Connected Route UP 0Sep 4 06:25:30.099 500 msec Connected Route UP 0Table 5 describes the significant fields shown in the display.
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