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Aggregating Services

An aggregate service is a type of value-added service that comprises a number of individual services. Combining services lets the SRC software treat the services within an aggregate service as a unit. When an aggregate service becomes active, it tries to activate all the services within it.

An aggregate service can distribute the activation of a number of services within the aggregate across one or more SAEs in an SRC network. This specialized service is ideal for supporting voice over IP (VoIP) and video on demand. To deliver these types of features to subscribers, you can configure bidirectional or unidirectional quality of service (QoS) services based on policies provisioned across a number of interfaces on one or more SAE-managed network devices in an SRC network. Figure 3 shows a sample aggregate service that provides end-to-end QoS for video on demand, with QoS Service 1 and QoS service 2 activated on Juniper Networks routers in the path between the video server and the subscriber.


Figure 3: Sample Configuration of an Aggregate Service

The services included in an aggregate service manage policies in the usual manner. The aggregate service does not directly manage any policies on a network device.

Fragment Services

The services that comprise an aggregate service are referred to as fragment services. This term provides a way to distinguish between services that are included in an aggregate service and those that are not. The fragment services can be any type of service that the SAE supports, except another aggregate service.

Subscriber Reference Expressions for Fragment Services

The configuration for each fragment service includes a subscriber reference expression, a phrase that identifies the subscriber sessions that activate the fragment service. The subscriber reference expression defines the subscriber session by subscriber IP address, DN, object path, login name, or associated virtual router.

To use aggregate services requires that the NIC be configured. Use a configuration scenario that provides a key for the type of subscriber reference expression defined for the fragment service. For example, if the subscriber reference expression is a DN, the NIC key is also a DN. In this case, you could use the NIC configuration scenario OnPopDnSharedIp, which uses a DN as a key.

For more information about the NIC configuration scenarios and the types of resolutions performed by these scenarios, see SRC-PE Network Guide, Chapter 19, NIC Configuration Scenarios.

Mandatory Services

A fragment service that must be active for an aggregate service to become active is called a mandatory service. When you configure an aggregate service, you specify which services, if any, are mandatory. For example, you could specify that rate-limiting services for a video-on-demand connection be mandatory to ensure call quality.

Redundant Services

When you configure an aggregate service, you can configure fragment services to provide redundancy for each other. Fragment services that share the same redundancy group name provide redundancy.

For an aggregate service to become active, at least one fragment service from each redundancy group must become active. For example, if you configure two services, S1 and S2, and assign the same redundancy group name to each of these services, S1 and S2 provide redundancy for each other if one becomes disabled.

While an aggregate service is active, the SAE tries to keep all fragment services within it active. An aggregate service and any of its active fragment services become inactive if a mandatory fragment service or an entire redundancy group becomes inactive.

Aggregate Service Sessions

An aggregate service session coordinates the activation of the services within it. It runs on the same SAE where it starts. The aggregate service session is created in the router driver that hosts the subscriber session that starts the service. An individual service session for a fragment service can be activated in the same SAE or another SAE on the SRC network.

Understanding how aggregate service sessions are managed can help you troubleshoot service activation or service deactivation issues that might arise. The SRC software provides a set of configurable timers that helps control session management.

Session Activation

An aggregate service becomes active when:

If a mandatory service does not start, the SAE deactivates any fragment services that are active.

If any fragment services that are not mandatory services do not become active, the aggregate service continues to try to start them. How long the aggregate service tries to activate fragment services depends on the settings for activation-deactivation time.

When an aggregate service becomes active, it monitors the services that are part of the aggregate service.

NOTE: Depending on your implementation, accounting software could detect that a fragment service session became active even though the associated aggregate service did not become active, resulting in the fragment services being deactivated.

You can configure your accounting software to ignore the activation of the fragment session when an aggregate service session fails. This way, a customer is not billed for an aggregate service that was not received.


Session Deactivation

When the SAE deactivates an aggregate service, the aggregate service session tries to deactivate the services within it. The SAE deactivates an aggregate service when all fragment services stop. If one of these services remains active, the aggregate service stays in memory until the service session ends. The SAE periodically tries to stop the active fragment session until the maximum retry time is reached, at which time it deactivates the aggregate service. As a result, the aggregate service session can remain in memory after the associated subscriber session ends.

Session Monitoring

An aggregate service session exchanges keepalive messages with a session management process for remote fragment services. This way, if a service session is removed from a router while the SAE is not managing the router, such as when the COPS client stops on a JUNOSe router or the configuration database is reset on a JUNOS routing platform, the SAE associated with the router receives notification that the keepalive message failed.

Service Activation

Aggregate services are activated in a similar way as any other value-added service, but with the additional requirement of activating the associated fragment services. Figure 4 shows a sample service activation for a video-on-demand service.


Figure 4: Aggregate Service Activation

The following process describes the service activation for a video-on-demand service, with Steps 1-4 illustrated in Figure 4.

  1. A subscriber requests a video-on-demand service through a residential portal.
  2. The residential portal requests the service through the SAE.
  3. The SAE activates a subscription for the associated aggregate service, and a session for the aggregate service becomes active.
  4. The aggregate service coordinates with the SAE, and the SAE tries to activate the fragment services that have been configured for the aggregate service.
  5. The aggregate service becomes active when:
  1. The aggregate service initiates accounting, if configured.

After the aggregate service becomes active, it monitors fragment services to ensure that they are still active. When the subscriber or the video server ends the video-on-demand session, the aggregate service tries to terminate active fragment services.

For detailed information about service activation, see SRC-PE Subscribers and Subscriptions Guide, Chapter 3, Subscriber Logins and Service Activation.

Before You Configure an Aggregate Service

Before you configure an aggregate service:

  1. Plan the aggregate services:
  1. Configure the fragment services.

See Adding a Normal Value-Added Service.

  1. If the aggregate service includes services to be activated remotely, ensure that the NIC is configured and running on each SAE that resides in your SRC network.
  2. Ensure that the NIC is configured to use a scenario that provides the appropriate type of key.

See Subscriber Reference Expressions for Fragment Services.

  1. Ensure that the SAEs can communicate with each other and the NIC host(s). Make sure that firewalls permit TCP and CORBA communication between the systems hosting the SAEs, and communication between the NIC host(s) and the SAE.

See SRC-PE Getting Started Guide, Chapter 34, Defining an Initial Configuration on a Solaris Platform.

  1. Ensure that the communication between SAEs is secure.

Follow the standards for your organization to ensure that communication between SAEs is protected.

  1. If the aggregate service is to include a fragment service on a remote SAE, ensure that the remote fragment service can become active by verifying that the fragment service is loaded on the remote SAE.

See Reviewing Service Status.

Adding an Aggregate Service

To use SDX Admin to add an aggregate service:

  1. In the navigation pane, right-click the Services folder, select New, and then select SSP Service.

The New SSP Service dialog box appears.

  1. Enter a unique name for the SSP service name in the Service Name field, and click OK.

An object for the new service appears in the navigation pane, and basic information about the new service appears in the Main tab of the SSP Service pane.

  1. In the Main tab, specify values for the following fields:

If you want to specify values for other fields in the Main tab, see Value-Added Service Fields.

  1. Click the Aggregate tab.

The Aggregate tab appears in the content pane.

  1. In the Aggregate tab, click New to define a fragment service to be included in the aggregate service.

The Service Fragment dialog box appears.

  1. Edit the values in the Service Fragment dialog box, and then click OK.

See Service Fragment Fields.

  1. In the Aggregate Service tab, click Add to add the fragment service to the aggregate service.
  2. Repeat Steps 5-7 for each fragment service to be added to the aggregate service.
  3. Click Save.

Configuration Examples for Aggregate Services

For configuration examples for aggregate services see the following guide:

Service Fragment Fields

In SDX Admin, you can modify the fields in this section to configure a fragment service for an aggregate service in the Service Fragment dialog box.

Expression

The <path> identifies the hierarchy of directory objects below the LDAP object o=aggregateService. The final object contains the attribute subscriberRefExpr to identify the subscriber session. A forward slash (/) separates the objects in the path.

For information about substitutions, see Configuring Substitutions.

For information about using Python expressions to represent values in a subscriber reference expression, see Using Python Expressions in a Subscriber Reference Expression.

To create Python expressions, use the fields in Table 6. You can specify more than one string in a Python script expression.

Service

Mandatory

Redundancy Group

Subscription

Setting this field to true lets you control which services can be used as fragments. For example, for an aggregate service that supports VoIP to push a policy to the caller and the callee, you can require that both subscribers sign up for VoIP services. If you set the field to false, only one party needs to subscribe to the aggregate service; the policy service sessions are created automatically.

Substitutions

For information about acquiring substitution values, see Chapter 14, Defining and Acquiring Values for Parameters.

Use commas to separate multiple substitutions.

Using Python Expressions in a Subscriber Reference Expression

You can compose Python expressions from one or more of the fields in Table 6 for the definition of a subscriber reference expression of a fragment service. You enter these expressions in the Expression field of the Fragment Service dialog box in which you define a fragment service for an aggregate service.

For information about configuring fragment services for an aggregate service, see Adding an Aggregate Service.




Table 6: Fields Used in Python Expressions for Aggregate Services  
Field
Description

substitution.<xyz>

Value of the substitution <xyz>.

Substitutions are acquired by means of the regular acquisition path for service sessions.

The name of substitutions is restricted to valid Python identifiers, such as 'ALPHA/"_" *(ALPHA/ DIGIT/"_")', with the exception of keywords, such as for, if, while, return, and, or, not, def, class, try, except. For the full list of Python keywords, see http://docs.python.org/ref/keywords.html.

loginType

The type of subscriber session, one of the following:

  • ASSIGNEDIP—An assigned IP login is triggered when an application accesses a subscriber object for an assigned IP subscriber that is not currently loaded into memory. (JUNOSe routers)
  • AUTHINTF—An AUTHINTF login is triggered when an interface responds to authentication, such as authentication for a PPP session. (JUNOSe routers)
  • INTF—An interface login is triggered when an interface comes up and the interface classifier script determines that the SAE should manage that interface, unless the interface comes up as a result of an authenticated PPP session. (JUNOS routing platforms and JUNOSe routers)
  • ADDR—An ADDR login is triggered when the DHCP server in the JUNOSe router provides a token IP address. (JUNOSe routers)
  • AUTHADDR—An AUTHADDR login is triggered when the DHCP server in the JUNOSe router provides a public IP address. (JUNOSe routers)
  • PORTAL—A portal login is triggered when the portal API is invoked by a JSP Web page to log in a subscriber. (JUNOS routing platforms and JUNOSe routers)

loginName

Login name provided by a subscriber

userName

Username portion of the loginName

domainName

Domain name portion of the loginName

serviceBundle

Content of the vendor-specific RADIUS attribute for service bundle

radiusClass

RADIUS class used for authorization

virtualRouterName

Name of virtual router in the format vrname@hostname

interfaceName

Name of the interface

ifAlias

Description of the interface configured on the router

ifDesc

Alternate name for the interface. This is the name used by the Simple Network Management Protocol (SNMP).

On a JUNOSe router the format of the description is:

ip<slot>/<port>.<subinterface>

On a JUNOS routing platform, ifDesc is the same as interfaceName.

nasPortId

Port identifier of an interface, including the interface name and additional layer 2 information (for example, fastEthernet 3/1)

macAddress

Text representation of the MAC address for the DHCP subscriber (for example. 00:11:22:33:44:55)

retailerDn

Distinguished name of the retailer

nasIp

NAS IP address of the router

dhcp

DHCP options. See SRC-PE Subscribers and Subscriptions Guide, Chapter 7, Classifying Interfaces and Subscribers on a Solaris Platform.

primaryUserName

The PPP or DHCP username. This name does not change when the subscriber logs in through a portal.


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