BoardHop_PCRF

© 2010 BroadHop, Inc. All Rights Reserved 6/14/2010 1

PCRF and the Evolution of Networking

Ian Campbell, Chief Architect, BroadHop, Inc. and

Chase Wolfinger Senior Technical Architect, BroadHop, Inc.

To successfully rollout global broadband services, network service providers need to control, monetize, and personalize their networks in order

to maximize their return on investment (ROI) and satisfy today’s savvy subscribers. Meeting these needs requires multiple levels of service, real-

time charging and quota management, on-demand and location-based applications, real-time service provisioning, quota and pre-paid services,

admission and access control, as well as voice, video, and data services that can be transported across multiple access network types.

Significantly more complex than the earliest networks, these next-generation networks must have the granularity to control access for each

individual subscriber, have the ability to automatically adjust a subscriber’s services in real time, and communicate with each subscriber, even

while working across converged, multi-access (wireless and wireline) networks. How is this achieved? By implementing a policy-driven approach,

network service providers can automate user self-provisioning, engage in two-way interactive communication with subscribers, maintain control,

charge accordingly, and maximize their ROI. The newest tool to achieve this is the policy charging and rules function (PCRF), which centralizes

network policy control.

What is PCRF?

It is a little hard to explain what PCRF is without first addressing a number of initials and acronyms. As a start, PCRF stands for policy charging

and rules function, and it evolved out of the 3GPP (‘third generation partnership product’ for 3G mobile networks) specification as a component

for IP Multimedia Subsystem networks (IMS), an architectural framework for delivering multimedia services using Internet Protocol (IP), a

common transport protocol that allows for access independence and enables a single-core multimedia network. (Today, PCRF is not exclusively

tied to IMS networks but is applicable across many network types.) To better understand how PCRF fits into a network, it might be helpful to take

a step back and gain a basic understanding of IMS and policy itself.

First, IMS1 is a network infrastructure that was specifically designed to handle detailed, real-time multimedia services that incorporate audio and

video components.2 IMS uses the session initiation protocol (SIP), which was developed for Internet traffic, to enable session setup and teardown.

In addition, IMS typically uses the Diameter protocol (which was derived from the RADIUS protocol)3 for policy and charging control (PCC). An

important contribution of IMS is that it introduced the concept of ‘access technology independence,’ meaning that various wireless and wireline

access networks and interfaces could come together in a single core network.

Originally introduced as part of the 3GPP IMS standardization effort in order to dynamically authorize and link IMS sessions with mobile packet

access resources, today policy plays a key role in the functionality of an IMS, 3G, or Long Term Evolution (LTE) network (regardless of the

access technology or air interface). Policy encompasses the business and technological rules that govern which network services a subscriber

can access, at what bandwidth level, when, and for how long. Generally speaking, the policy function queries, coordinates, and adjusts all of the

network resources to provide the required services to individual, authorized subscribers. It identifies the appropriate policy rules for the situation

and enforces them.4

1 “So, what is this IMS thingy??” http://theimsjungle.wordpress.com/. April 27, 2008. Accessed December 8, 2009.2 Boden, John. “IMS:Addressing the infrastructure challenges of converged multimedia services delivery” http://www.nortel.com/corporate/news/collateral/ntj4_ims.pdf. Accessed

December 11, 2009.3 “Introduction to Diameter” http://www.ibm.com/developerworks/wireless/library/wi-diameter/. Accessed December 8, 2009.4 “Introduction to the Policy Function,” http://www.wimax.com/commentary/spotlight/evolution-of-qos-and-charging-framework-in-wimax. Accessed December 8, 2009.


Despite its inception as part of the 3GPP initiative, the PCRF concept has evolved along its own path. While not necessarily tied to GSM, 3GPP,

IMS, or LTE networks exclusively, the PCRF is typically compatible with them. Most importantly, PCRF enables the policy function for multimedia

networks.

As a policy tool, the PCRF plays a central role in next-generation networks. Unlike earlier policy engines that were added on to an existing

network to enforce policy, the PCRF is a software component that operates at the network core and efficiently accesses subscriber databases and

other specialized functions, such as a charging systems, in a scalable, reliable, and centralized manner.

One could think of the PCRF as the part of the network architecture that aggregates information to and from the network, operational support

systems, and other sources (such as portals) in real time, supporting the creation of rules and then automatically making intelligent policy

decisions for each subscriber active on the network. Such a network might offer multiple services, quality of service (QoS) levels, and charging

rules.

Figure 1 shows a policy-based, tiered, mobile-services use case. In this example, the advanced PCRF policy server acts on direct customer

requests to manage service plans, service classes, and available bandwidth. It interacts with multiple network elements including policy and

charging enforcement functions (PCEFs) such as mobile gateway GPRS support nodes (GGSNs) and deep packet inspection devices (DPIs). In

addition, this advanced PCRF solution uses charging system and subscriber database information to deliver personalized and profitable services.

As an example of personalized services, a subscriber could access a network portal and sign up to try a turbo boost feature for an hour, sending

a message to the PCRF through the portal. After the PCRF receives the request, it sends a message to upgrade that particular subscriber’s Mb/s

rate and updates billing records.

Figure 1: An advanced PCRF solution can enable tiered, mobile services that personalize services and improve the quality of experience for each individual subscriber.


Why Policy Control?

Ultimately service providers want their customers to consider them to be a relevant, necessary part of their personal and professional lives. To

achieve this, service providers must be able to deliver their services across all types of networks, and they must be confident in their ability to

imagine, create, and rapidly deploy any number of innovative and highly personalized new services.

The problem is that networks and operational software systems (OSS) are inherently complex and continue to be difficult to integrate. To address

this, some providers are implementing a more standard infrastructure, such as IMS or the TM Forum’s NGOSS. Some are also adding an IT-based

layer called a service delivery platform (SDP). However, even with these changes, operational complexity can still make innovation challenging,

limiting the subscriber experience and leaving significant market share available for non-traditional communication providers.

Policy control addresses all of these issues because it shapes services to meet both customer and carrier requirements. Strategically placed

between the network and the OSS, the policy control function bridges services across any type of network or device, interprets and acts on

pre-existing and real-time subscriber and service information, and functions as a centralized, simplified, and still very powerful single point for

service deployment and control.

What should service providers know about PCRF?

PCRF is the primary decision point in the network that brings subscriber profiles (Gold, Silver, Bronze), services (voice, video, data), and charging

rules to the network transport layer. Providers can make specific services available to particular subscribers, charge them differently, and

enforce business rules in real time on the network.

It is important to understand that there are different types of PCRF architectures, each with a range of different capabilities (see “Selecting your

policy solution” below). As part of its basic definition, a PCRF must support all of the 3GPP interface protocols and reference points, including Rx,

Gx, and Sp. As a result, the concept of PCRF is often focused solely on 3G protocols, and many PCRF products that are labeled as ‘3GPP Version

8.0 Compliant,’ do not support non-standard interfaces. But, the PCRF product does not have to be limited to 3G interfaces alone.

In fact, an advanced PCRF architecture can support custom interfaces within a network, regardless of whether the access technologies are

wireless (such as Wi-Fi™ or WiMAX™) or wireline broadband. This is particularly important when a network element does not have an industry-

standard interface, or if legacy equipment is involved. These types of hybrid networks require a flexible PCRF that easily supports devices that

are not fully-compliant with current specifications. In addition, a PCRF can also be tied to a specific vendor (such as Juniper, Arbor, or Cisco), or it

can be an open platform that allows the integration and interoperability of equipment from multiple vendors.

Also consider that there is no ‘standard’ configuration or usage for a PCRF. For instance, the PCRF function could be supplied with a graphical user

interface, it can come with pre-configured rules and a policy builder function that allows non-engineering personnel to build policy and business

rules for the network, or it could require a specially-trained development engineer or integrator to write custom software, then deploy and test it.


Who should deploy PCRF?Any service provider who wants to integrate multiple access technologies in a converged IMS network could benefit from a PCRF. By using a PCRF as the primary decision point in the network, service providers can embed policy control within the infrastructure. They can automatically optimize and manage available resources and services. A PCRF enables tiered voice, video, data, and location-based service offerings, and it supports new charging and quota management models, all while managing quality of service (or performing ‘congestion management’), which is particularly important in mobile networks. With a highly functional PCRF component, service providers can successfully provide individualized services to their subscribers, charge them accordingly, and enforce business rules in real time on their networks.

Depending on the PCRF product selected, the following applications or ‘use cases’ may be supported:

Fair Usage and Quota Control

When fair usage is activated, the service provider defines indicators that automatically reduce the bandwidth for a particular service or user, optimizing the load on network resources and user experiences for all subscribers in real time. Automated quota control, usage notifications, and redirecting users to a payment or services portal when quota is reached may also be supported.

Network/Smartphone Congestion

Bandwidth-intensive applications such as streaming video are becoming more popular, but they can result in network congestion during peak hours. Using real-time information from the access network, the PCRF allows the service provider to restrict a subscriber’s usage based on user class and/or apply fair use policies to intensive-use subscribers during times of congestion.

Parental Control

Parental control and enterprise control are important features for today’s networks. With this feature, parents or enterprises can limit access to certain services during specific times of the day and apply content filtering. If a restriction is detected, the session may be redirected to a notification server and denied access to the regulated services.

Time of Day Services

With time-of-day services, the PCRF can limit basic users during certain hours, and augment them outside of peak hours when there is excess capacity on the network. Or, service providers can block or limit certain services, such as streaming video or peer-to-peer networking during specific times.

Service and User Differentiation

PCRF automatically allocates the appropriate QoS depending on the activity of the subscriber (email, voice, web-browsing) and the access technology (LTE, DSL, HSPA, 3G, 2G). Service providers can also allocate a specific QoS depending on the priority of the subscriber (business versus residential subscriber, for instance).

Service Bundling

With this feature, service providers can use the PCRF to manage services as a group or a bundle rather than individually. They can also rapidly create ‘tiered’ services, offering diversified packages to appeal to a broad range of subscribers.


Charging Policies

PCRF can provide service providers with a range of charging policies. For example, they can easily enact postpaid/prepaid charging categories, activate prepaid accounts, and define and offer hourly/daily/monthly data passes.

Roaming Services

With PCRF’s location-based policies, it is possible to rapidly enact roaming controls, allow or restrict services depending on geography, track variable billing schemes that are based on location (e.g. domestic, international), and set up home-zone charging plans.

Security Policy Management

A PCRF can enable service providers to select a security policy, including firewalls and content filtering. A service policy can include parental controls, time of day policies, intelligent congestion management, peer-to-peer control or blocking, and session or service steering to make the best possible use of network resources.

Promotions

A PCRF can be used to quickly design, launch, and enforce special promotions, including bandwidth on demand or ‘turbo button’ services.

Selecting a policy solutionThere are a number of policy solution options available, and several PCRF ones. Here’s a checklist of the basics available with any PCRF solution:

• Redundancyandcarrier-gradeperformance

• Multi-vendorsupport(e.g.supportsGSMsystemsfromEricssonaswellasNokia)

• Multi-standardsupport,including3GPP/DiameterinterfacessuchasGx,Rx,Gy,S9,andSp,webservices,RADIUS,DHCPleasequery,and

vendor-specific interfaces

However before selecting a policy solution, be sure to determine these capabilities:

Service Velocity and Flexibility

Given how rapidly the broadband market is changing, do you know exactly what applications, services, and network equipment you will need now and over the next 36 months? If yes, then you can select any policy vendor. If not, then it is critical to select an open platform that allows rapid deployment of new policy as new capabilities are added. Without an open platform, such as the Quantum Network Suite™ from BroadHop, service providers will more than likely have to go back to the vendor for new code. With an open platform, Java-trained systems integrators can develop the new code. With the Quantum Network Suite, for example, developers can leverage the Open Policy SDK (which allows operators to build new APIs to extend the platform on their own) and Policy Builder (which allows rapid deployment of new policy rules).

Two-Way Interaction

The development and uptake of smartphones have dramatically changed the way consumers use their mobile devices on your network. Radio access networks that were originally designed to handle cellular voice calls are being overwhelmed. Even after upgrading networks to increase bandwidth for voice, data, and video services, service providers can greatly benefit from a policy server that can automatically communicate with subscribers about the current network status and service upgrade options. An advanced PCRF solution, such as the Quantum Network Suite, can effectively manage bandwidth and service tiers for subscribers, ensuring quality of service for premium subscribers, and offering automatic upgrades for other subscribers.


What PCRF products are available?

PCRF products are available now. The

industry leader in policy deployments,

BroadHop offers the Quantum Network

Suite™, the most advanced rules engine

technology available. It allows service

providers to deploy centralized and

localized policy rules, enabling new

service and revenue models as service

providers drive policy right to the handset.

The first open policy application platform

based on the advanced PCRF architecture,

Quantum Network Suite is also the

first fully-virtualized policy platform,

featuring a massively scalable virtual

node application architecture that handles

hundreds of millions of transactions.

With Quantum Network Suite, service

providers can deploy two-way interactive

policy, allowing for personalized services

and enhanced quality of experience for

subscribers. One of the things that makes

Quantum Network Suite unique is that

it separates application development

from the underlying network structure,

resulting in a 10X improvement in service

and application creation.

Working with any network infrastructure,

Quantum Network Suite represents the

next generation in policy control, moving

away from a network-centric Policy 1.0

model to an application-centered Policy

2.0 one.

Multi-technology Support

Today’s networks use multiple access technologies and are made up of legacy and new network equipment. The PCRF solution should support all of these access technologies and network types, including Wi-Fi offload support in a converged wireline/wireless network.

Scaling

Ensure that the policy solution makes it possible to easily add extra capacity into the network. Much of the newer access technologies, such as LTE and Wi-Fi, are ‘always-on’ architectures, which demand more capacity as subscribers move around the network.

The Power of the Policy Engine

How smart is the policy engine? Can it automatically streamline the information it collects and send only what the network really needs? Or must it constantly track and report data that isn’t required? For instance, if it is necessary to know a subscriber’s cell site, the Quantum Network Suite automatically turns on that level of reporting for that subscriber. If it is not necessary, it does not report it, eliminating a lot of additional signaling on the network. The best policy solution can balance protecting the network against congesting it.

Because of its unique features, the BroadHop Quantum Network Suite can be used to solve the industry’s most difficult challenges:

• Mobiledatacongestionmanagementandtiering

• Usagecaps,billshockprevention,continentalroaming

• Fairuseandmulti-servicequotamanagement

• 3Gmobiledataoffload(mobilecoreprotection)

• Fixed-mobileconvergentservices,femto-solutions

• Interactiveuserqualityofexperienceandloyaltybuilding

• LocationandIdentity-basedservices,ads,andcontent

• Advancedservicesdevelopment

For more information on how the BroadHop Quantum Network Suite can address today's network challenges, visit http://www.broadhop.com/products_qns.html or contact BroadHop at [email protected].

BoardHop_PCRF

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