Example 1: Mobile IP Support Using the System as an HA
The system supports both Simple and Mobile IP. For Mobile IP applications, the system can be configured to perform the function of a PDSN/FA and/or a HA. This example describes what is needed for and how the system performs the role of the HA. Example number 1 provides information on using the system to provide PDSN/FA functionality.
The system\'s HA configuration for Mobile IP applications requires that at least two contexts (one source and one destination) be configured as shown in the following figure.
The source context will facilitate the HA service(s), the Pi interfaces from the FA, and the AAA interfaces. The source context will also be configured to provide Home AAA functionality for subscriber sessions. The destination context will facilitate the PDN interface(s).
Information Required
Prior to configuring the system as shown in this example, there is a minimum amount of information required. The following sections describe the information required to configure the source and destination contexts.
Source Context Configuration
The following table lists the information that is required to configure the source context.
Required Information | Description | ||
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Source context name |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the source context will be recognized by the system.
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Pi Interface Configuration | |||
Pi interface name |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the interface will be recognized by the system. Multiple names are needed if multiple interfaces will be configured. Pi interfaces are configured in the destination context. If this interface is being used for Interchassis Session Recovery, you must specify a loopback interface type after the interface_name. |
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IP address and subnet |
These will be assigned to the Pi interfaces.Multiple addresses and/or subnets are needed if multiple interfaces will be configured. |
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Physical port number |
This specifies the physical port to which the interface will be bound. Ports are identified by the chassis slot number where the line card resides in, followed by the number of the physical connector on the line card. For example, port 17/1 identifies connector number 1 on the card in slot 17. A single physical port can facilitate multiple interfaces. |
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Physical port description |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the physical port will be recognized by the system. Multiple descriptions are needed if multiple ports will be used. Physical ports are configured within the destination context and are used to bind logical Pi interfaces. |
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Gateway IP address(es) |
Used when configuring static routes from the Pi interfaces to a specific network. |
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HA service Configuration | |||
HA service name |
This is an identification string between 1 and 63 characters (alpha and/or numeric) by which the HA service will be recognized by the system. Multiple names are needed if multiple HA services will be used. HA services are configured in the destination context. |
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UDP port number for Mobile IP traffic |
Specifies the port used by the HA service and the FA for communications. The UDP port number can be any integer value between 1 and 65535. The default value is 434. |
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Mobile node re-registration requirements |
Specifies how the system should handle authentication for mobile node re-registrations.The HA service can be configured as follows:
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FA-to-HA Security Parameter Index Information |
FA IP address: The HA service allows the creation of a security profile that can be associated with a particular FA. This specifies the IP address of the FA that the HA service will be communicating with. Multiple FA addresses are needed if the HA will be communicating with multiple FAs. |
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Index: Specifies the shared SPI between the HA service and a particular FA. The SPI can be configured to any integer value between 256 and 4294967295. Multiple SPIs can be configured if the HA service is to communicate with multiple FAs. |
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Secret: Specifies the shared SPI secret between the HA service and the FA. The secret can be between 1 and 127 characters (alpha and/or numeric). An SPI secret is required for each SPI configured. |
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Hash-algorithm: Specifies the algorithm used to hash the SPI and SPI secret. The possible algorithms that can be configured are MD5 per RFC 1321 and keyed-MD5 per RFC 2002. The default algorithm is hmac-md5.A hash-algorithm is required for each SPI configured. |
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Mobile Node Security Parameter Index Information |
Index: Specifies the shared SPI between the HA service and the mobile node(s). The SPI can be configured to any integer value between 256 and 4294967295.Multiple SPIs can be configured if the HA service is to communicate with multiple mobile nodes. |
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Secret(s): Specifies the shared SPI secret between the HA service and the mobile node. The secret can be between 1 and 127 characters (alpha and/or numeric).An SPI secret is required for each SPI configured. |
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Hash-algorithm: Specifies the algorithm used to hash the SPI and SPI secret. The possible algorithms that can be configured are MD5 per RFC 1321 and keyed-MD5 per RFC 2002. The default algorithm is hmac-md5.A hash-algorithm is required for each SPI configured. |
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Replay-protection process: Specifies how protection against replay-attacks is implemented. The possible processes are nonce and timestamp. The default is timestamp with a tolerance of 60 seconds. A replay-protection process is required for each mobile node-to-HA SPI configured. |
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Maximum registration lifetime |
Specifies the longest registration lifetime that the HA service will allow in any Registration Request message from the mobile node. The time is measured in seconds and can be configured to any integer value between 1 and 65534. An infinite registration lifetime can also be configured by disabling the timer. The default is 600. |
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Maximum number of simultaneous bindings |
Specifies the maximum number of "care-of" addresses that can simultaneously be bound for the same user as identified by NAI and Home address. The number can be configured to any integer value between 1 and 5. The default is 3. |
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AAA Interface Configuration | |||
AAA interface name |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the interface will be recognized by the system. Multiple names are needed if multiple interfaces will be configured. AAA interfaces will be configured in the source context. |
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IP address and subnet |
These will be assigned to the AAA interface.Multiple addresses and/or subnets are needed if multiple interfaces will be configured. |
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Physical port number |
This specifies the physical port to which the interface will be bound. Ports are identified by the chassis slot number where the line card resides in, followed by the number of the physical connector on the line card. For example, port 17/1 identifies connector number 1 on the card in slot 17. A single physical port can facilitate multiple interfaces. |
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Physical port description |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the physical port will be recognized by the system. Multiple descriptions are needed if multiple ports will be used. Physical ports are configured within the source context and are used to bind logical AAA interfaces. |
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Gateway IP address |
Used when configuring static routes from the AAA interface(s) to a specific network. |
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Home RADIUS Server Configuration | |||
Home RADIUS Authentication server |
IP Address: Specifies the IP address of the home RADIUS authentication server the source context will communicate with to provide subscriber authentication functions. Multiple addresses are needed if multiple RADIUS servers will be configured.Home RADIUS authentication servers are configured within the source context. Multiple servers can be configured and each assigned a priority. |
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Shared Secret: The shared secret is a string between 1 and 15 characters (alpha and/or numeric) that specifies the key that is exchanged between the RADIUS authentication server and the source context. A shared secret is needed for each configured RADIUS server. |
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UDP Port Number: Specifies the port used by the source context and the home RADIUS authentication server for communications. The UDP port number can be any integer value between 1 and 65535. The default value is 1812. |
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Home RADIUS Accounting server |
IP Address: Specifies the IP address of the home RADIUS accounting server that the source context will communicate with to provide subscriber accounting functions. Multiple addresses are needed if multiple RADIUS servers will be configured. Home RADIUS accounting servers are configured within the source context. Multiple servers can be configured and each assigned a priority. |
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Shared Secret: The shared secret is a string between 1 and 15 characters (alpha and/or numeric) that specifies the key that is exchanged between the RADIUS accounting server and the source context.A shared secret is needed for each configured RADIUS server. |
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UDP Port Number: Specifies the port used by the source context and the home RADIUS Accounting server for communications. The UDP port number can be any integer value between 1 and 65535. The default value is 1813. |
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RADIUS attribute NAS Identifier |
Specifies the name by which the source context will be identified in the Access-Request message(s) it sends to the home RADIUS server. The name must be between 1 and 32 alpha and/or numeric characters and is case sensitive. |
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RADIUS NAS IP address |
Specifies the IP address of the source context\'s AAA interface. A secondary address can be optionally configured. |
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Default Subscriber Configuration | |||
"Default" subscriber\'s IP context name |
Specifies the name of the egress context on the system that facilitates the PDN ports.
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Destination Context Configuration
Required Information | Description | ||
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Destination context name |
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PDN Interface Configuration | |||
PDN interface name |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the interface will be recognized by the system. Multiple names are needed if multiple interfaces will be configured. PDN interfaces are configured in the destination context. |
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IP address and subnet |
These will be assigned to the PDN interface.Multiple addresses and/or subnets are needed if multiple interfaces will be configured. |
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Physical port number |
This specifies the physical port to which the interface will be bound. Ports are identified by the chassis slot number where the line card resides in, followed by the number of the physical connector on the line card. For example, port 17/1 identifies connector number 1 on the card in slot 17. A single physical port can facilitate multiple interfaces. |
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Physical port description |
This is an identification string between 1 and 79 characters (alpha and/or numeric) by which the physical port will be recognized by the system. Multiple descriptions are needed if multiple ports will be used. Physical ports are configured within the destination context and are used to bind logical PDN interfaces. |
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Gateway IP address(es) |
Used when configuring static routes from the PDN interface(s) to a specific network. |
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IP Address Pool Configuration | |||
IP address pool name |
Each IP address pool is identified by a name. The pool name can be between 1 and 31 alpha and/or numeric characters and is case sensitive. IP address pools are configured in the destination context(s). Multiple address pools can be configured within a single context. |
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IP pool addresses |
An initial address and a subnet, or a starting address and an ending address, are required for each configured pool. The pool will then consist of every possible address within the subnet , or all addresses from the starting address to the ending address.The pool can be configured as public, private, or static. If this IP pool is being used for Interchassis Session Recovery, it must be a static and srp-activated. |
How This Configuration Works
The following figure and the text that follows describe how this configuration with a single source and destination context would be used by the system to process a Mobile IP data call.
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A subscriber session from the FA is received by the HA service over the Pi interface.
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The HA service determines which context to use to provide AAA functionality for the session. This process is described in the How the System Selects Contexts section located in the Understanding the System Operation and Configuration chapter of the System Administration Guide.
For this example, the result of this process is that the HA service determined that AAA functionality should be provided by the Source context.
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The system then communicates with the Home AAA server specified in the Source context\'s AAA configuration to authenticate the subscriber.
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Upon successful authentication, the Source context determines which egress context to use for the subscriber session. This process is described in the How the System Selects Contexts section located in the Understanding the System Operation and Configuration chapter of the System Administration Guide.
For this example, the system determines that the egress context is the Destination context based on the configuration of the Default subscriber.
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An IP address is assigned to the subscriber\'s mobile node from an IP address pool configured in the destination context. This IP address is used for the duration of the session and then be returned to the pool.
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Data traffic for the subscriber session is then routed through the PDN interface in the Destination context.
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Accounting messages for the session are sent to the AAA server over the AAA interface.