Using Identity Caching
Cisco Prime Access Registrar (Prime Access Registrar) software includes the identity caching feature. Prime Access Registrar runs as application layer software and can be used standalone or in conjunction with other workstations running Prime Access Registrar.
Note The identity caching feature is available on Prime Access Registrar releases 3.5.2 and above.
Identity caching provides subscriber identity resolution services with fast access to associated subscriber identity data for service providers, enabling them to offer new services to their customers based on identity caching and context information management.
This chapter contains the following sections:
•Identity Caching Features
•Configuring Cisco Prime Access Registrar for Identity Caching
•Starting Identity Caching
Identity caching enables Cisco equipment to gain context information about the operator's subscribers to support network functions or to enhance subscriber's experience on the operator's network. Figure 14-1, Prime Access Registrar System Overview, shows the network environment where Prime Access Registrar identity caching might be used.
For example, Client Services Gateway (CSG) uses IP mapping information provided by identity caching to support post-paid content billing. Identity caching acquires subscriber information from other devices and information sources in the operator's network. The type of information provided is limited by the available information sources and is configurable by the operator, but might include information such as IP address, MSISDN, and IMSI. Identity caching does not duplicate the operator's persistent data stores. Identity caching provides a protocol-based interface through which Cisco network elements (Prime Access Registrar identity caching clients) can access subscriber information.
The Prime Access Registrar servers receive RADIUS flows from the Gateway GPRS support Node (GGSN) which acts as a type of network access station (NAS). These flows perform full AAA (authentication, authorization, and accounting). You can configure the Prime Access Registrar servers to redirect the accounting information (only) to an identity caching server to be cached. The GGSN can also be configured to direct only the RADIUS accounting information directly to the Prime Access Registrar server.
Prime Access Registrar also receives XML identity query flows from the CSM which acts as a NAS. In the event that a CSM should fail or lose its information, the information can be refreshed from the information cached in the Prime Access Registrar server.
Prime Access Registrar acquires subscriber information such as the IP address, the mobile Subscriber ISDN number (MSISDN), and the International Mobile System Identifier (IMSI) from AAA requests the Prime Access Registrar server receives, typically from the GGSN. The types of information provided is limited by the available information sources and is configurable by the operator.
Prime Access Registrar includes an XML Query Identity enhancement. Prime Access Registrar previously supported User-Name lookup based on the Framed IP address of an existing session. The XML Query Identity enhancement enables Framed IP address lookup based on the User-Name in an existing session.
Figure 14-1 Prime Access Registrar System Overview
Identity Caching Features
Prime Access Registrar identity caching provides the following features:
•Supports GGSN subscriber data attributes from RADIUS authentication sequences
•Provides basic identity mapping services from IP address or username/APN to Mobile DN for one network presence at a time.
•Provide session management support for Content Switch Module (CSM)
Prime Access Registrar enables the CSM to keep the data session and content correlated to the same subscriber reconnecting, perhaps after an attach/detach sequence for a GPRS subscriber connecting again. This is done through the MSISDN identity to IP mapping in the identity caching function.
•Enhance redundancy with stateful fail-over support for applications by finding the right connection between subscriber identity and IP address using the Identity Cache function.
•Uses an XML interface to make it easier for any network function or application to use without having to have detailed internal knowledge about the execution environment or programming methods.
•Provides user identity resolution with fast access to associated subscriber data
•Establishes an identity and Access Management solution that can be used in and across multiple network domains
•Provides a way to use identity resolution to manage the growth of 2.5G mobile data access services (GSM/GPRS) and to provide always-on mobile data access including the following:
–Ties various IP addresses to a unique subscriber identifier
–Dynamically assigning and reusing IP addresses and controlling services with consistent identification
–Correlates previous content activity when a mobile subscriber reconnects
–Correlates IP addresses, mobile numbers, username, and identifiers to support customer billing
–Correlates and identifies subscribers using both 2.5G and WLAN services and provides a way to control and manage operator network services
–Provides subscriber privacy control
–Provides a way to cache content with various customers and their networks
Configuring Cisco Prime Access Registrar for Identity Caching
Use the command line interface aregcmd to configure Prime Access Registrar to perform identity caching.
Configuring the Identity Caching
To configure identity caching:
Step 1 Launch aregcmd.
Step 2 Define a client object for each client that will send either RADIUS or XML packets to the Prime Access Registrar server performing identity caching.
There should be one client object for each GGSN, one for each CSM and one for each packet simulator (if used in a test environment).
For example, if a packet simulator will be used on the same server where you perform identity caching, add a client object as in the following:
[ //localhost/Radius/Clients/xml-client ]
This client object is very similar to the localhost object defined in the example configuration. The SharedSecret property will be ignored if the client is an XML client, but still must be set to a non-null value. The Type property is also ignored for XML clients.
Step 3 Define a port object for each RADIUS port and each XML port to be used. Two RADIUS ports, the second immediately following the first in numeric value, must be defined even if only one is needed. A typical identity caching installation requires the following port configuration:
Note Although ports 1645 and 1646 are the default ports for Prime Access Registrar, you must add them to /Radius/Advanced/Ports to also add port 8080.
Step 4 Change directory to the 1645 port and set its type to Radius-Access.
set Type Radius-Access
Step 5 Change directory to the 1646 port and set its type to Radius-Accounting.
set Type Radius-Accounting
Step 6 Change directory to the 8080 port and set its type to XML.
set Type XML
Step 7 Define and configure an accounting service of type file and set it as the DefaultAccountingService.
An accounting service is required for Prime Access Registrar to cache identity information, even if no accounting service is needed otherwise. If you added the example configuration during installation, a local-file accounting service is already configured.
If you did not add the example configuration during software installation, see the Setting Up Accounting section in Chapter 7 "RADIUS Accounting."
Step 8 Define and configure a ResourceManager for identity caching.
Step 9 Set the ResourceManager to type session-cache for identity caching.
set type session-cache
The following shows the default properties of a session-cache ResourceManager:
[ //localhost/Radius/ResourceManagers/cache ]
OverwriteAttributes = FALSE
Step 10 Set the QueryKey to a RADIUS attribute you want to key on.
For example, use the following command to set the QueryKey to User-Name:
set QueryKey User-Name
The QueryKey must match the string on the right-hand side of one of the pairs you list in QueryMappings. It is not necessary for the QueryKey to be configured under AttributesToBeCached because the QueryKey will always be cached by default.
Note The QueryKey property must always be a RADIUS attribute. The Prime Access Registrar server forces a NULL IP address (0.0.0.0) if it detects an incorrectly configured QueryKey.
Step 11 Change directory to AttributesToBeCached and use the set command to provide a list of RADIUS attributes you want to store in cache.
set 1 Calling-Station-ID
Set 2 User-Name
Set 3 Framed-IP-Address
The attributes a session-cache resource manager caches can be queried through both RADIUS Query and XML Query packets. When you cache attributes Framed-IP-Address or User-Name, or when you use XML-Address-format-IPv4 or XML-UserId-id_type-subscriber_id as the QueryKey, you must map the XML attributes to RADIUS attributes in the QueryMappings subdirectory.
Step 12 Change directory to QueryMappings and use the set command to list the attribute pairs, mapping the XML attributes on the left-hand side to the RADIUS attribute on the right-hand side.
set XML-Address-format-IPv4 Framed-IP-Address
set XML-UserId-id_type-subscriber_id User-Name
Step 13 Change directory to /Radius/SessionManagers and add a SessionManager for identity caching.
Step 14 Change directory to the new identity caching SessionManager, then change directory to the ResourceManager list.
Step 15 Use the set command to associate the identity caching ResourceManager with this SessionManager.
set 1 cache
Step 16 Change directory to /Radius and set the DefaultSessionManager to the identity caching SessionManager.
set DefaultSessionManager IDcache
Step 17 Run the save, reload, and exit commands:
Starting Identity Caching
To start identity caching, you must send an Accounting-Request to the specified accounting port (The default accounting port is 1646.) A minimal Accounting-Request will contain the following attributes:
•NAS-Identifier or NAS-IP-Address
Starting Identity Caching
To start identity caching:
Step 1 Launch radclient:
radclient -C localhost -N admin -P aicuser
Step 2 Enter the following radclient commands:
set p [ acct_request Start firstname.lastname@example.org ]
$p set attrib [ attrib Framed-IP-Address 220.127.116.11 ]
This assumes that you are running radclient on the same server and using 1646 as the accounting port.
Step 3 Send XML requests to the specified XML port (Cisco suggests port 8080 as shown above). A typical XML packet will look like the following:
To do this using xmlclient, put the XML text into a file, then enter the following command:
./xmlclient -srd <file>
Note This assumes that xmlclient is running on the same server as identity caching and that 8080 is the XML port. Use the command xmlclient -H for information about how to use a different port or how to run xmlclient from a different server.
Note For a successful query, xml response will have the IPAddress associated with the requested user-name and for failure query it returns 0.0.0.0 as the IPAddress.
The XML interface is used for subscriber context information queries and responses to those queries. The XML interface is on a UDP port (8080) and is configurable. Identity caching supports the XML data-type definition (DTD) supported by the CSG.
The mapping from queries to replies can be one to many. For example, a UDP datagram might contain several queries but each reply will be returned in a separate datagram. No single query or reply can exceed the configured MTU of a datagram. Any that does results in an error.
If a query result is negative, the reply will consist of a null subscriber ID. All other error conditions cause Prime Access Registrar to drop the request. Errors are logged locally using the Prime Access Registrar logging mechanism.