Table Of Contents
ISDN Backup in MPLS Core
Contents
Prerequisites for ISDN Backup in MPLS Core
Restrictions for ISDN Backup in MPLS Core
Information About ISDN Backup in MPLS Core
How ISDN Backup in MPLS Core Works
Benefits of ISDN Backup in MPLS Core Feature
How to Configure ISDN Backup in MPLS Core
Configuring Primary Interface for Backup
Configuring the Dialer Profile as Backup Interface
Verifying the ISDN Backup for MPLS Feature
Configuration Examples for ISDN Backup in MPLS Core
ISDN Backup for MPLS Example
Additional References
Related Documents
Standards
MIBs
RFCs
Technical Assistance
ISDN Backup in MPLS Core
When a primary link is down in the Multiprotocol Label Switching (MPLS) core network, the ISDN Backup in MPLS Core feature allows a backup ISDN link on a dialer interface to be brought up to restore network connectivity. This feature ensures high availability of the link between two routers in the MPLS core by providing a backup mechanism.
Feature Specifications for the ISDN Backup in MPLS Core feature
Feature History
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Release
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Modification
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12.3(2)T
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This feature was introduced.
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Supported Platforms
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Cisco 3640 series, Cisco 7200 series
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Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Contents
•Prerequisites for ISDN Backup in MPLS Core
•Restrictions for ISDN Backup in MPLS Core
•Information About ISDN Backup in MPLS Core
•How to Configure ISDN Backup in MPLS Core
•Configuration Examples for ISDN Backup in MPLS Core
•Additional References
Prerequisites for ISDN Backup in MPLS Core
You need to first configure the Dialer Persistent feature.
Restrictions for ISDN Backup in MPLS Core
•The ISDN Backup in MPLS Core feature works only with dialer profile configuration.
•The ISDN Backup in MPLS Core feature is available only for PPP encapsulation.
Information About ISDN Backup in MPLS Core
Before configuring and implementing the ISDN Backup for MPLS Core feature, you should understand the following concepts:
•How ISDN Backup in MPLS Core Works
•Benefits of ISDN Backup in MPLS Core Feature
How ISDN Backup in MPLS Core Works
The dialer profile interface is configured as backup to the primary interface. The dialer interface should have the Dialer Persistent feature configured and MPLS IP should be enabled with encapsulation PPP. For more information on the Dialer Persistent feature refer to the Cisco IOS Dial Technologies Configuration Guide, Release 12.3.
When the primary interface goes down, the dialer profile that is acting as the backup will bring up the backup interface without waiting for any interesting traffic because Dialer Persistent has been configured. Once the link to the destination is established, tagged packets will flow via the dialer interface.
Benefits of ISDN Backup in MPLS Core Feature
The ISDN Backup in MPLS Core feature provides MPLS switching support on dialer interfaces for ISDN backup in MPLS core networks. When you configure a backup ISDN link on a dialer interface, the dialer interface can be brought up to restore network connectivity when a primary link goes down in an MPLS core network.
How to Configure ISDN Backup in MPLS Core
This section contains the following procedures:
•Configuring Primary Interface for Backup
•Configuring the Dialer Profile as Backup Interface
•Verifying the ISDN Backup for MPLS Feature
Configuring Primary Interface for Backup
Perform this task to configure a primary interface backup.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type slot/port.subinterface-number [multipoint | point-to-point]
4. backup interface dialer number
5. exit
DETAILED STEPS
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Command or Action
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Purpose
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Step 1
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enable
Example:
Router> enable
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Enables privileged EXEC mode.
•Enter your password if prompted.
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Step 2
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configure terminal
Example:
Router# configure terminal
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Enters global configuration mode.
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Step 3
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interface type slot/port.subinterface-number
[multipoint | point-to-point]
Example:
Router(config)# interface serial 1
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Configures an interface type and enters interface configuration mode.
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Step 4
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backup interface dialer number
Example:
Router(config-if)# backup interface dialer 1
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Configures an interface as a secondary or dial backup interface.
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Step 5
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exit
Example:
Router(config-if)# exit
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Returns to global configuration mode.
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Configuring the Dialer Profile as Backup Interface
Perform this task to configure the Dialer Persistent feature on the backup interface.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface dialer number
4. encapsulation type
5. dialer persistent [delay [initial] seconds | max-attempts number]
6. tag-switching ip (interface configuration)
7. exit
DETAILED STEPS
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Command or Action
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Purpose
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Step 1
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enable
Example:
Router> enable
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Enables privileged EXEC mode.
•Enter your password if prompted.
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Step 2
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configure terminal
Example:
Router# configure terminal
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Enters global configuration mode.
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Step 3
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interface dialer number
Example:
Router(config)# interface dialer 1
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Creates a dialer interface and enters interface configuration mode.
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Step 4
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encapsulation type
Example:
Router(config-if)# encapsulation ppp
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Specifies the encapsulation type.
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Step 5
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dialer persistent [delay [initial] seconds |
max-attempts number]
Example:
Router(config-if)# dialer persistent delay
initial 20
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Forces a dialer interface to be connected at all times, even in the absence of interesting traffic.
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Step 6
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tag-switching ip
Example:
Router(config-if)# tag-switching ip
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Enables label switching of IPv4 packets on an interface.
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Step 7
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exit
Example:
Router(config-if)# exit
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Returns to global configuration mode.
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Verifying the ISDN Backup for MPLS Feature
Perform this task to verify that you have correctly configured the ISDN Backup for MPLS feature.
SUMMARY STEPS
1. enable
2. show mpls forwarding-table
3. show mpls interfaces [interface] [detail]
4. exit
DETAILED STEPS
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Command or Action
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Purpose
|
Step 1
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enable
Example:
Router> enable
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Enables privileged EXEC mode.
•Enter your password if prompted.
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Step 2
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show mpls forwarding-table
Example:
Router# show mpls forwarding-table
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Displays the contents of the MPLS FIB.
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Step 3
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show mpls interfaces [interface] [detail]
Example:
Router(config)# show mpls interfaces dialer
detail
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Displays the contents of the Multiprotocol Label Switching (MPLS) label forwarding information base (LFIB).
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Step 4
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exit
Example:
Router(config)# exit
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Returns to global configuration mode.
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Configuration Examples for ISDN Backup in MPLS Core
This section provides the following configuration example:
•ISDN Backup for MPLS Example
ISDN Backup for MPLS Example
The following example shows the interface Dialer 1 being configured as the backup interface.
ip address 172.16.1.1 255.0.0.0
ip address 172.16.1.3 255.0.0.0
Additional References
The following sections provide additional references related to the ISDN Backup in MPLS Core feature.
Related Documents
Standards
MIBs
RFCs
Technical Assistance
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