Table Of Contents
OSPF Link-State Advertisement (LSA) Throttling
Prerequisites for OSPF LSA Throttling
Information About OSPF LSA Throttling
Benefits of OSPF LSA Throttling
How to Customize OSPF LSA Throttling
Customizing OSPF LSA Throttling
Configuration Examples for OSPF LSA Throttling
debug ip ospf database-timer rate-limit
show ip ospf timers rate-limit
OSPF Link-State Advertisement (LSA) Throttling
The OSPF Link-State Advertisement (LSA) Throttling feature provides a dynamic mechanism to slow down link-state advertisement (LSA) updates in OSPF during times of network instability. It also allows faster Open Shortest Path First (OSPF) convergence by providing LSA rate limiting in milliseconds.
History for the OSPF LSA Throttling Feature
Finding Support Information for Platforms and Cisco IOS Software Images
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Contents
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Prerequisites for OSPF LSA Throttling
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Information About OSPF LSA Throttling
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How to Customize OSPF LSA Throttling
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Configuration Examples for OSPF LSA Throttling
Prerequisites for OSPF LSA Throttling
It is presumed that you have OSPF configured in your network.
Information About OSPF LSA Throttling
Before you enable OSPF LSA Throttling, you should understand the following concepts:
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Benefits of OSPF LSA Throttling
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How OSPF LSA Throttling Works
Benefits of OSPF LSA Throttling
Prior to the OSPF LSA Throttling feature, LSA generation was rate-limited for 5 seconds. That meant that changes in an LSA could not be propagated in milliseconds, so the OSPF network could not achieve millisecond convergence.
The OSPF LSA Throttling feature is enabled by default and allows faster OSPF convergence (in milliseconds). This feature can be customized. One command controls the generation (sending) of LSAs and another command controls the receiving interval. This feature also provides a dynamic mechanism to slow down the frequency of LSA updates in OSPF during times of network instability.
How OSPF LSA Throttling Works
The timers throttle lsa all command controls the generation (sending) of LSAs. The first LSA is always generated immediately upon an OSPF topology change, and the next LSA generated is controlled by the minimum start interval. The subsequent LSAs generated for the same LSA are rate-limited until the maximum interval is reached. The "same LSA" is defined as an LSA instance that contains the same LSA ID number, LSA type, and advertising router ID.
The timers lsa arrival command controls the minimum interval for accepting the same LSA. If an instance of the same LSA arrives sooner than the interval that is set, the LSA is dropped. It is recommended that the arrival interval be less than or equal to the hold-time interval of the timers throttle lsa all command.
How to Customize OSPF LSA Throttling
This section contains the following optional procedure:
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Customizing OSPF LSA Throttling (optional)
Customizing OSPF LSA Throttling
This task describes how to customize OSPF LSA throttling if you prefer to set values other than the defaults.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
router ospf process-id
4.
timers throttle lsa all start-interval hold-interval max-interval
5.
timers lsa arrival milliseconds
6.
end
7.
show ip ospf timers rate-limit
8.
show ip ospf
DETAILED STEPS
Configuration Examples for OSPF LSA Throttling
This section contains an example of customizing OSPF LSA throttling:
OSPF LSA Throttling: Example
This example customizes OSPF LSA throttling so that the start interval is 200 milliseconds, the hold interval is 10,000 milliseconds, and the maximum interval is 45,000 milliseconds. The minimum interval between instances of receiving the same LSA is 2000 milliseconds.
router ospf 1log-adjacency-changestimers throttle lsa all 200 10000 45000timers lsa arrival 2000network 10.10.4.0 0.0.0.255 area 24network 10.10.24.0 0.0.0.255 area 24Additional References
The following sections provide references related to OSPF LSA throttling.
Related Documents
Standards
Standards TitleNo new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
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MIBs
MIBs MIBs LinkNone
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
RFCs
RFCs TitleNo new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
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Technical Assistance
Command Reference
This section documents modified commands only.
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debug ip ospf database-timer rate-limit
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show ip ospf timers rate-limit
debug ip ospf database-timer rate-limit
To display when link-state advertisement (LSA) rate-limiting timers will expire, use the debug ip ospf database-timer rate-limit command in privileged EXEC mode.
debug ip ospf database-timer rate-limit [access-list-number]
Syntax Description
Command Modes
Privileged EXEC
Command History
Release Modification12.0(25)S
This command was introduced.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Usage Guidelines
Use this command if you need to see when the timers will expire per LSA. Use an access list if you want to limit the output.
Examples
The following is sample output from the debug ip ospf database-timer rate-limit command for an example configuration that includes the timers throttle lsa all 100 10000 45000 command. Comments are inserted to explain the preceding output.
Router# debug ip ospf database-timer rate-limitOSPF rate limit timer events debugging is on*Mar 12 20:18:20.383:OSPF:Starting rate limit timer for 10.10.24.410.10.24.4 1 with 100ms delayThe interface is shut down, which causes OSPF to generate a new router LSA. The system starts a timer for 100 milliseconds.
*Mar 12 20:18:20.495:OSPF:Rate limit timer is expired for 10.10.24.410.10.24.4 1The rate limit timer is expired after 100 milliseconds (a small delta is added to the timer).
*Mar 12 20:18:20.495:OSPF:For next LSA generation - wait :10000ms next:20000ms*Mar 12 20:18:20.495:OSPF:Build router LSA for area 24, router ID10.10.24.4, seq 0x80000003The system will generate update a router LSA after the timer expires.
show ip ospf
To display general information about Open Shortest Path First (OSPF) routing processes, use the show ip ospf command in EXEC mode.
show ip ospf [process-id]
Syntax Description
process-id
(Optional) Process ID. If this argument is included, only information for the specified routing process is included.
Command Modes
EXEC
Command History
Examples
The following is sample output from the show ip ospf command when entered without a specific OSPF process ID:
Router# show ip ospf
Routing Process "ospf 201" with ID 10.0.0.1 and Domain ID 10.20.0.1Supports only single TOS(TOS0) routesSupports opaque LSASPF schedule delay 5 secs, Hold time between two SPFs 10 secsMinimum LSA interval 5 secs. Minimum LSA arrival 1 secsLSA group pacing timer 100 secsInterface flood pacing timer 55 msecsRetransmission pacing timer 100 msecsNumber of external LSA 0. Checksum Sum 0x0Number of opaque AS LSA 0. Checksum Sum 0x0Number of DCbitless external and opaque AS LSA 0Number of DoNotAge external and opaque AS LSA 0Number of areas in this router is 2. 2 normal 0 stub 0 nssaExternal flood list length 0Area BACKBONE(0)Number of interfaces in this area is 2Area has message digest authenticationSPF algorithm executed 4 timesArea ranges areNumber of LSA 4. Checksum Sum 0x29BEBNumber of opaque link LSA 0. Checksum Sum 0x0Number of DCbitless LSA 3Number of indication LSA 0Number of DoNotAge LSA 0Flood list length 0Area 172.16.26.0Number of interfaces in this area is 0Area has no authenticationSPF algorithm executed 1 timesArea ranges are192.168.0.0/16 Passive AdvertiseNumber of LSA 1. Checksum Sum 0x44FDNumber of opaque link LSA 0. Checksum Sum 0x0Number of DCbitless LSA 1Number of indication LSA 1Number of DoNotAge LSA 0Flood list length 0Table 1 describes the significant fields shown in the display.
The following is an excerpt of output from the show ip ospf command when the OSPF Forwarding Address Suppression in Type-5 LSAs feature is configured:
Router# show ip ospf...Area 2Number of interfaces in this area is 4It is a NSSA areaPerform type-7/type-5 LSA translation, suppress forwarding address...Routing Process "ospf 1" with ID 192.168.0.1Supports only single TOS(TOS0) routesSupports opaque LSASupports Link-local Signaling (LLS)Initial SPF schedule delay 5000 msecsMinimum hold time between two consecutive SPFs 10000 msecsMaximum wait time between two consecutive SPFs 10000 msecsIncremental-SPF disabledMinimum LSA interval 5 secsMinimum LSA arrival 1000 msecsLSA group pacing timer 240 secsInterface flood pacing timer 33 msecsRetransmission pacing timer 66 msecsNumber of external LSA 0. Checksum Sum 0x0Number of opaque AS LSA 0. Checksum Sum 0x0Number of DCbitless external and opaque AS LSA 0Number of DoNotAge external and opaque AS LSA 0Number of areas in this router is 0. 0 normal 0 stub 0 nssaExternal flood list length 0Table 2 describes the significant fields shown in the display.
The following is sample output from the show ip ospf command. In this example, the user had configured the redistribution maximum-prefix command to set a limit of 2000 redistributed routes. Shortest Path First (SPF) throttling was configured with the timers throttle spf command.
Router# show ip ospf 1
Routing Process "ospf 1" with ID 10.0.0.1Supports only single TOS(TOS0) routesSupports opaque LSASupports Link-local Signaling (LLS)It is an autonomous system boundary routerRedistributing External Routes from,static, includes subnets in redistributionMaximum limit of redistributed prefixes 2000Threshold for warning message 75%Initial SPF schedule delay 5000 msecsMinimum hold time between two consecutive SPFs 10000 msecsMaximum wait time between two consecutive SPFs 10000 msecsTable 3 describes the significant fields shown in the display.
The following is sample output from the show ip ospf command. In this example, the user had configured LSA throttling, and those lines of output are displayed in bold.
Router# show ip ospf 1
Routing Process "ospf 4" with ID 10.10.24.4Supports only single TOS(TOS0) routesSupports opaque LSASupports Link-local Signaling (LLS)Initial SPF schedule delay 5000 msecsMinimum hold time between two consecutive SPFs 10000 msecsMaximum wait time between two consecutive SPFs 10000 msecsIncremental-SPF disabledInitial LSA throttle delay 100 msecs
Minimum hold time for LSA throttle 10000 msecs
Maximum wait time for LSA throttle 45000 msecs
Minimum LSA arrival 1000 msecsLSA group pacing timer 240 secsInterface flood pacing timer 33 msecsRetransmission pacing timer 66 msecsNumber of external LSA 0. Checksum Sum 0x0Number of opaque AS LSA 0. Checksum Sum 0x0Number of DCbitless external and opaque AS LSA 0Number of DoNotAge external and opaque AS LSA 0Number of areas in this router is 1. 1 normal 0 stub 0 nssaExternal flood list length 0Area 24Number of interfaces in this area is 2Area has no authenticationSPF algorithm last executed 04:28:18.396 agoSPF algorithm executed 8 timesArea ranges areNumber of LSA 4. Checksum Sum 0x23EB9Number of opaque link LSA 0. Checksum Sum 0x0Number of DCbitless LSA 0Number of indication LSA 0Number of DoNotAge LSA 0Flood list length 0The following is sample output from the show ip ospf command. In this example, the user had configured the redistribution maximum-prefix command to set a limit of 2000 redistributed routes. Shortest Path First (SPF) throttling was configured with the timers throttle spf command.
Router# show ip ospf 1
Routing Process "ospf 1" with ID 10.0.0.1Supports only single TOS(TOS0) routesSupports opaque LSASupports Link-local Signaling (LLS)It is an autonomous system boundary routerRedistributing External Routes from,static, includes subnets in redistributionMaximum limit of redistributed prefixes 2000Threshold for warning message 75%Initial SPF schedule delay 5000 msecsMinimum hold time between two consecutive SPFs 10000 msecsMaximum wait time between two consecutive SPFs 10000 msecsTable 4 describes significant fields shown in the display.
The following is sample output from the show ip ospf command. In this example, the user had configured LSA throttling, and those lines of output are displayed in bold.
Router# show ip ospf 1
Routing Process "ospf 4" with ID 10.10.24.4Supports only single TOS(TOS0) routesSupports opaque LSASupports Link-local Signaling (LLS)Initial SPF schedule delay 5000 msecsMinimum hold time between two consecutive SPFs 10000 msecsMaximum wait time between two consecutive SPFs 10000 msecsIncremental-SPF disabledInitial LSA throttle delay 100 msecs
Minimum hold time for LSA throttle 10000 msecs
Maximum wait time for LSA throttle 45000 msecs
Minimum LSA arrival 1000 msecsLSA group pacing timer 240 secsInterface flood pacing timer 33 msecsRetransmission pacing timer 66 msecsNumber of external LSA 0. Checksum Sum 0x0Number of opaque AS LSA 0. Checksum Sum 0x0Number of DCbitless external and opaque AS LSA 0Number of DoNotAge external and opaque AS LSA 0Number of areas in this router is 1. 1 normal 0 stub 0 nssaExternal flood list length 0Area 24Number of interfaces in this area is 2Area has no authenticationSPF algorithm last executed 04:28:18.396 agoSPF algorithm executed 8 timesArea ranges areNumber of LSA 4. Checksum Sum 0x23EB9Number of opaque link LSA 0. Checksum Sum 0x0Number of DCbitless LSA 0Number of indication LSA 0Number of DoNotAge LSA 0Flood list length 0show ip ospf timers rate-limit
To display all of the link-state advertisements (LSAs) in the rate limit queue, use the show ip ospf timers rate-limit command in privileged EXEC mode.
show ip ospf timers rate-limit
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
Release Modification12.0(25)S
This command was introduced.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Usage Guidelines
Use this command if you need to see when LSAs in the queue will be sent.
Examples
The following is sample output from the show ip ospf timers rate-limit command:
Router# show ip ospf timers rate-limit
LSAID: 10.1.1.1 Type: 1 Adv Rtr: 172.16.2.2 Due in: 00:00:00.028
LSAID: 172.16.4.1 Type: 3 Adv Rtr: 172.16.2.2 Due in: 00:00:00.028
Table 1 describes the significant fields shown in the display.
timers lsa arrival
To set the minimum interval at which the software accepts the same link-state advertisement (LSA) from OSPF neighbors, use the timers lsa arrival command in router configuration mode. To restore the default value, use the no form of this command.
timers lsa arrival milliseconds
no timers lsa arrival
Syntax Description
milliseconds
Minimum delay in milliseconds that must pass between acceptance of the same LSA arriving from neighbors. The range is 0 to 600,000 milliseconds. The default is 1000 milliseconds.
Defaults
1000 milliseconds
Command Modes
Router configuration
Command History
Release Modification12.0(25)S
This command was introduced.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Usage Guidelines
The timers lsa arrival command controls the minimum interval for accepting the same LSA. The "same LSA" is defined as an LSA instance that contains the same LSA ID number, LSA type, and advertising router ID. If an instance of the same LSA arrives sooner than the interval that is set, the LSA is dropped.
We suggest you keep the milliseconds value of the timers lsa arrival command less than or equal to the neighbors' hold-interval value of the timers throttle lsa all command.
Examples
The following example sets the minimum interval for accepting the same LSA at 2000 milliseconds:
router ospf 1log-adjacency-changestimers throttle lsa all 200 10000 45000timers lsa arrival 2000network 10.10.4.0 0.0.0.255 area 24network 10.10.24.0 0.0.0.255 area 24Related Commands
Command Descriptionshow ip ospf timers rate-limit
Displays all of the LSAs in the rate limit queue.
timers throttle lsa all
Sets rate-limiting values for LSAs being generated.
timers throttle lsa all
To set rate-limiting values for Open Shortest Path First (OSPF) link-state advertisement (LSA) generation, use the timers throttle lsa all command in router configuration mode. To restore the default values, use the no form of this command.
timers throttle lsa all start-interval hold-interval max-interval
no timers throttle lsa all
Syntax Description
Defaults
start-interval: 0 milliseconds
hold-interval: 5000 milliseconds
max-interval: 5000 millisecondsCommand Modes
Router configuration
Command History
Release Modification12.0(25)S
This command was introduced.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Usage Guidelines
The "same LSA" is defined as an LSA instance that contains the same LSA ID number, LSA type, and advertising router ID. We suggest you keep the milliseconds value of the timers lsa arrival command less than or equal to the hold-interval value of the timers throttle lsa all command.
Examples
This example customizes OSPF LSA throttling so that the start interval is 200 milliseconds, the hold interval is 10,000 milliseconds, and the maximum interval is 45,000 milliseconds. The minimum interval between instances of receiving the same LSA is 2000 milliseconds.
router ospf 1log-adjacency-changestimers throttle lsa all 200 10000 45000timers lsa arrival 2000network 10.10.4.0 0.0.0.255 area 24network 10.10.24.0 0.0.0.255 area 24Related Commands
Command Descriptionshow ip ospf
Displays information about OSPF routing processes.
timers lsa arrival
Sets the minimum interval at which the software accepts the same LSA from OSPF neighbors.
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