IP Routing Configuration Guide, Cisco IOS XE Bengaluru 17.5.x (Catalyst 9500 Switches)

Bias-Free Language

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

Book Contents
Find Matches in This Book

Results

Updated:
March 31, 2021

Chapter: Configuring Prefix Suppression Support for OSPFv3

Configuring Prefix Suppression Support for OSPFv3

Prerequisites for Prefix Suppression Support for OSPFv3

Before you can use the mechanism to exclude IPv4 and IPv6 prefixes from LSAs, the OSPFv3 routing protocol must be configured.

Information About Prefix Suppression Support for OSPFv3

The following sections provide information about prefix suppression support for OSPFv3

OSPFv3 Prefix Suppression Support

The OSPFv3 Prefix Suppression Support feature allows you to hide IPv4 and IPv6 prefixes that are configured on interfaces running OSPFv3.

In OSPFv3, addressing semantics have been removed from the OSPF protocol packets and the main LSA types, leaving a network-protocol-independent core. This means that Router-LSAs and network-LSAs no longer contain network addresses, but simply express topology information. The process of hiding prefixes is simpler in OSPFv3 and suppressed prefixes are simply removed from the intra-area-prefix-LSA. Prefixes are also propagated in OSPFv3 via link LSAs

The OSPFv3 Prefix Suppression feature provides a number of benefits.The exclusion of certain prefixes from adverstisements means that there is more memory available for LSA storage, bandwidth and buffers for LSA flooding, and CPU cycles for origination and flooding of LSAs and for SPF computation. Prefixes are also filtered from link LSAs. A device only filters locally configured prefixes, not prefixes learnt via link LSAs. In addition, security has been improved by reducing the possiblity of remote attack with the hiding of transit-only networks.

Globally Suppress IPv4 and IPv6 Prefix Advertisements by Configuring the OSPFv3 Process

You can reduce OSPFv3 convergence time by configuring the OSPFv3 process on a device to prevent the advertisement of all IPv4 and IPv6 prefixes by using the prefix-suppression command in router configuration mode or address-family configuration mode.


Note

Prefixes that are associated with loopbacks, secondary IP addresses, and passive interfaces are not suppressed by the router mode or the address-family configuration commands because typical network designs require prefixes to remain reachable.

Suppress IPv4 and IPv6 Prefix Advertisements on a Per-Interface Basis

You can explicitly configure an OSPFv3 interface not to advertise its IP network to its neighbors by using the ipv6 ospf prefix-suppression command or the ospfv3 prefix-suppression command in interface configuration mode.


Note

If you have globally suppressed IPv4 and IPv6 prefixes from connected IP networks by configuring the prefix-suppression router configuration command, the interface configuration command takes precedence over the router configuration command.

How to Configure Prefix Suppression Support for OSPFv3

The following sections provide configuration examples for prefix suppression support for OSPFv3.

Configuring Prefix Suppression Support of the OSPFv3 Process

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. router ospfv3 process-id [vrf vpn-name ]
  4. prefix-suppression
  5. end
  6. show ospfv3

DETAILED STEPS

  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 [vrf vpn-name ]

Example:


Device(config)# router ospfv3 23

Configures an OSPFv3 routing process and enters router configuration mode.

Step 4

prefix-suppression

Example:


Device(config-router)# prefix-suppression

Prevents OSPFv3 from advertising all IPv4 and IPv6 prefixes, except prefixes that are associated with loopbacks, secondary IP addresses, and passive interfaces.

Step 5

end

Example:


Device(config-router)# end

Returns to privileged EXEC mode.

Step 6

show ospfv3

Example:


Device# show ospfv3

Displays general information about OSPFv3 routing processes.

Note

 

Use this command to verify that IPv4 and IPv6 prefix suppression has been enabled.

Configuring Prefix Suppression Support of the OSPFv3 Process in Address-Family Configuration Mode

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. router ospfv3 process-id [vrf vpn-name ]
  4. address-family ipv6 unicast
  5. prefix-suppression
  6. end
  7. show ospfv3

DETAILED STEPS

  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 [vrf vpn-name ]

Example:


Device(config)# router ospfv3 23

Configures an OSPFv3 routing process and enters router configuration mode.

Step 4

address-family ipv6 unicast

Example:

Device(config-router)# address-family ipv6 unicast

Enters IPv6 address family configuration mode for OSPFv3.

Step 5

prefix-suppression

Example:


Device(config-router-af)# prefix-suppression

Prevents OSPFv3 from advertising all IPv4 and IPv6 prefixes, except prefixes that are associated with loopbacks, secondary IP addresses, and passive interfaces.

Step 6

end

Example:


Device(config-router-af)# end

Returns to privileged EXEC mode.

Step 7

show ospfv3

Example:


Device# show ospfv3

Displays general information about OSPFv3 routing processes.

Note

 

Use this command to verify that IPv4 and IPv6 prefix suppression has been enabled.

Configuring Prefix Suppression Support on a Per-Interface Basis

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. Do one of the following:
    • ipv6 ospf prefix-suppression [disable ]
    • ospfv3 prefix-suppression disable
  5. end
  6. show ospfv3 interface

DETAILED STEPS

  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

interface type number

Example:


Device(config)# interface serial 0/0

Configures an interface type and enters interface configuration mode.

Step 4

Do one of the following:

  • ipv6 ospf prefix-suppression [disable ]
  • ospfv3 prefix-suppression disable

Example:


Device(config-if)# ipv6 ospf prefix-suppression

Example:


Device(config-if)# ospfv3 1 prefix-suppression disable

Prevents OSPFv3 from advertising IPv4 and IPv6 prefixes that belong to a specific interface, except those that are associated with secondary IP addresses.

  • When you enter the ipv6 ospf prefix-suppression command or the ospfv3 prefix-suppression command in interface configuration mode, it takes precedence over the prefix-suppression command that is entered in router configuration mode.

Step 5

end

Example:


Device(config-if)# end

Returns to privileged EXEC mode.

Step 6

show ospfv3 interface

Example:


Device# show ospfv3 interface

Displays OSPFv3-related interface information.

Note

 

Use this command to verify that IPv4 and IPv6 prefix suppression has been enabled for a specific interface.

Troubleshooting IPv4 and IPv6 Prefix Suppression

SUMMARY STEPS

  1. enable
  2. debug ospfv3 lsa-generation
  3. debug condition interface interface-type interface-number [dlci dlci ] [vc {vci | vpi | vci }]
  4. show debugging
  5. show logging [slot slot-number | summary ]

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

debug ospfv3 lsa-generation

Example:


Device# debug ospfv3 lsa-generation

Displays informations about each OSPFv3 LSA that is generated.

Step 3

debug condition interface interface-type interface-number [dlci dlci ] [vc {vci | vpi | vci }]

Example:


Device# debug condition interface serial 0/0

Limits output for some debug commands on the basis of the interface or virtual circuit.

Step 4

show debugging

Example:


Device# show debugging

Displays information about the types of debugging that are enabled for your device.

Step 5

show logging [slot slot-number | summary ]

Example:


Device# show logging

Displays the state of syslog and the contents of the standard system logging buffer.

Configuration Example: Configuring Prefix Suppression Support for OSPFv3


router ospfv3 1
 prefix-suppression
 !
 address-family ipv6 unicast
  router-id 0.0.0.6
  exit-address-family

The following example shows how to configure prefix suppression support for OSPFv3 in address-family configuration mode: 


router ospfv3 1
 !
 address-family ipv6 unicast
  router-id 10.0.0.6
  prefix-suppression
  exit-address-family

The following example shows how to configure prefix suppression support for OSPFv3 in interface configuration mode: 


interface Ethernet0/0
 ip address 10.0.0.1 255.255.255.0
 ipv6 address 2001:201::201/64
 ipv6 enable
 ospfv3 prefix-suppression
 ospfv3 1 ipv4 area 0
 ospfv3 1 ipv6 area 0
 end

Feature History for Prefix Suppression Support for OSPFv3

This table provides release and related information for the features explained in this module.

These features are available in all the releases subsequent to the one they were introduced in, unless noted otherwise.

Release

Feature

Feature Information

Cisco IOS XE Fuji 16.8.1a

Prefix Suppression Support for OSPFv3

Prefix Suppression Support for OSPFv3 feature enables Open Shortest Path First version 3 (OSPFv3) to hide the IPv4 and IPv6 prefixes of connected networks from link-state advertisements (LSAs).

Was this Document Helpful?

FeedbackFeedback

Contact Cisco