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Cisco Configuring OSPF Limit on Number of Redistributed Routes: User Guide and Manual PDF (EN)
Оригинальное название: Cisco Configuring OSPF Limit on Number of Redistributed Routes: User Guide and Manual PDF
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Information About OSPF Limit on Number of Redistributed Routes
Configuring OSPF Limit on Number of Redistributed Routes Restrictions for OSPF Limit on Number of Redistributed Routes, on page 1 Prerequisites for OSPF Limit on Number of Redistributed Routes, on page 1 Information About OSPF Limit on Number of Redistributed Routes, on page 1 How to Configure an OSPF Limit on the Number of Redistributed Routes, on page 2 Configuration Examples for OSPF Limit on Number of Redistributed Routes, on page 6 Feature History for OSPF Limit on Number of Redistributed Routes, on page 7 Restrictions for OSPF Limit on Number of Redistributed Routes OSPFv3 Limit on Number of Redistributed Routes is supported only for the IPv6 address family.
Prerequisites for OSPF Limit on Number of Redistributed Routes You must have Open Shortest Path First (OSPF) configured in your network either along with another protocol, or another OSPF process for redistribution. InformationAboutOSPFLimitonNumberofRedistributedRoutes OSPF supports a user-defined maximum number of prefixes (routes) that can be redistributed into OSPF from other protocols or other OSPF processes. Such a limit helps prevent the device from being flooded by too many redistributed routes. For example, if a large number of IP routes are sent into OSPF for a network that allows redistribution of Border Gateway Protocol (BGP) into OSPF, the network can get severely flooded.
Limiting the number of redistributed routes prevents this potential problem. From Cisco IOS XE Dublin 17.11.1, the command redistribute maximum-prefix maximum[threshold] is enabled with the default number of routes set at 10240 routes. The default number of routes is to protect the OSPF processes from being flooded with routes. You can still configure the number of routes using the redistribute maximum-prefix command. The OSPF Limit on Number of Redistributed Routes feature is applicable to OSPF, OSPFv2 and OSPFv3. Configuring OSPF Limit on Number of Redistributed Routes 1
Limiting the Number of OSPF Redistributed Routes
How to Configure an OSPF Limit on the Number of Redistributed Routes The following sections provide information on configuring an OSPF limit on the number of redistributed routes. The following procedures are mutually exclusive, that is, you can either limit the number of redistributed routes, or request a warning about the number of routes redistributed into OSPF. Note Limiting the Number of OSPF Redistributed Routes This task describes how to limit the number of OSPF redistributed routes. If the number of redistributed routes reaches the maximum value configured, no more routes are redistributed.
Procedure Configuring OSPF Limit on Number of Redistributed Routes How to Configure an OSPF Limit on the Number of Redistributed Routes Command or Action Purpose Step 1 enable Example: Device> enable Enables privileged EXEC mode. Enter your password, if prompted. Step 2 configure terminal Example: Device# configure terminal Enters global configuration mode. Step 3 router ospf process-id Example: Device(config)# router ospf 1 Configures an OSPF routing process. Step 4 redistribute protocol [process-id] [as-number] [include-connected {level-1 | level-1-2 | level-2} [metric metric-value ] [metric-type type-value] [nssa-only] [tag tag-value] [route-map map-tag] Example:
Device(config-router-af)# redistribute eigrp 10 Redistributes routes from one routing domain into another routing domain. Step 5 redistribute maximum-prefix maximum [threshold] Example: Sets a maximum number of IP prefixes that are allowed to be redistributed into OSPF. • The default value for the maximum argument is set at 10240 routes. Configuring OSPF Limit on Number of Redistributed Routes 2
Limiting the Number of OSPFv3 Redistributed Routes
Limiting the Number of OSPFv3 Redistributed Routes This task describes how to limit the number of OSPFv3 redistributed routes. If the number of redistributed routes reaches the maximum value configured, no more routes are redistributed. Procedure Configuring OSPF Limit on Number of Redistributed Routes Limiting the Number of OSPFv3 Redistributed Routes Command or Action Purpose Device(config-router-af)# redistribute maximum-prefix 100 80 • The threshold value defaults to 75 percent. Note If the warning-only keyword is configured in this command, no limit is enforced; a warning message is logged. Step 6 end Example: Device(config-router)# end Exits router configuration mode.
Command or Action Purpose Step 1 enable Example: Device> enable Enables privileged EXEC mode. Enter your password, if prompted. Step 2 configure terminal Example: Device# configure terminal Enters global configuration mode. Step 3 router ospfv3 process-id Example: Device(config)# router ospfv3 1 Configures an OSPFv3 routing process. Step 4 address-family ipv6 [unicast] Example: Device(config-router)# address-family ipv6 unicast Enters IPv6 address family configuration mode. Step 5 redistribute protocol [process-id] [as-number] [include-connected {level-1 | level-1-2 | level-2} [metric metric-value ] [metric-type type-value] [nssa-only] [tag tag-value] [route-map map-tag] Example:
Device(config-router-af)# redistribute eigrp 10 Redistributes routes from one routing domain into another routing domain. Configuring OSPF Limit on Number of Redistributed Routes 3
Requesting a Warning Message About the Number of Routes Redistributed into OSPF
Requesting a Warning Message About the Number of Routes Redistributed into OSPF To request a warning message when the number of routes redistributed into OSPF exceeds the configuration limit, perform this procedure: Procedure Configuring OSPF Limit on Number of Redistributed Routes Requesting a Warning Message About the Number of Routes Redistributed into OSPF Command or Action Purpose Step 6 redistribute maximum-prefix maximum [threshold] Example: Device(config-router-af)# redistribute maximum-prefix 100 80 Sets a maximum number of IPv6 prefixes that are allowed to be redistributed into OSPFv3. • The default value for the maximum argument is set at 10240 routes.
• The threshold value defaults to 75 percent. Note If the warning-only keyword is configured in this command, no limit is enforced; a warning message is logged. Step 7 exit-address-family Example: Device(config-router-af)# exit-address-family Exits IPv6 address family configuration mode. Step 8 end Example: Device(config-router)# end Exits router configuration mode. Command or Action Purpose Step 1 enable Example: Device> enable Enables privileged EXEC mode. Enter your password, if prompted. Step 2 configure terminal Example: Device# configure terminal Enters global configuration mode. Step 3 router ospf process-id Example: Device(config)# router ospf 1 Configures an OSPF routing process.
Configuring OSPF Limit on Number of Redistributed Routes 4