Standards-based Online Charging - Maximizing Utility€¦ · Standards-Based Online Charging –...

Standards-Based Online Charging – Maximizing Utility

Contents

Executive Summary ................................... 1

Overview ................................................ 2

Simplistic traffic classification and diameter Gy hacks .......................................... 2

General Opportunities and Challenges ......... 3

The Policy Charging and Control Architecture 4

Quota-based Service Creation – Making it Work FOR You ....................................................... 4

The PTS Advantage – Bringing PCRF Decision to the Right Place ..................................... 5

The Policy Engine ............................... 5

The Traffic Classification technology ....... 6

Standards Meet High-Speed, Real-Time Flow Evaluation ........................................... 6

Diameter Gy Implementation ................. 7

Diameter Gx Implementation ................ 11

Comparing Charging Approaches – Gy vs. Gx . 11

The PCEF, the OCS and Diameter Gy ....... 11

The PCRF and Gx Usage Monitoring ......... 12

Use Cases - Diameter Gy vs. Diameter Gx . 13

Conclusion ............................................. 13

Executive Summary As operators use Network Policy Control to deploy new services through online charging, many are finding that success can depend on the specific deployment implementation.

To enable innovative and flexible charging models for application layer traffic (social media, real-time entertainment, cloud storage, etc.) a solution must include a modern traffic classification system that looks beyond simple port values and signatures. When an Online Charging System is in play, it must also support the Gy interface standard in its entirety without resorting to questionable “hacks”.

Simplistic Traffic Classification technology, and its inconsistent application by internet transport devices sourced from different vendors, is a root cause for revenue leakage and can limit an operator’s ability to introduce competitive differentiators to the market. Incomplete standards support for the Gy interface can also result in revenue leakage, as well as balance shortfalls, excessive control plane signaling to the Online Charging System, and increased chance of operational issues. Poor metering capabilities and a “hack” of the Gy interface standards can also produce unexpected costs related to interoperability and customization, delaying operators from meeting their targeted incremental average revenue per user, which is the whole point of the solution deployment.

In this paper, Sandvine shares expertise and explores several options available to operators for charging-related service creation. We show the value of fine-grained metering for Gx Monitoring, and how the proper use of the Gy interface, with full visibility of application traffic flows, provides the optimum deployment for creating services and additional revenue. This paper also discusses the value that Sandvine’s Traffic Classification technology and Policy Engine bring to enabling cost-effective online charging service creation for over-the-top internet traffic.


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Overview There was a time when communications service provider (CSP) revenue growth was proportional to increased traffic volume, with network costs tied to the traffic growth associated with additional subscription. Those days have been brought to a close by the massive proliferation of bandwidth-guzzling multimedia application traffic that runs “over-the-top” (OTT) of the data communications infrastructure. The enthusiastic consumer adoption of applications such as Netflix and Facebook has changed the business mechanics of traditional internet data delivery. CSPs are therefore using Network Policy Control to implement real-time charging services that create new revenue streams, encourage industry competition, and empower subscribers with choice.

The use case that online charging targets is primarily the situation where subscribers are not charged for their service on a regular postpaid. Instead, subscribers prepay for any service they subscribe to and any service used is paid on an ongoing basis, in real time, from that prepaid credit. When a subscriber wants to use a prepaid service, the network needs to determine the individual’s authorization and balance status and make quota reservations from the associated account in real time. While the real-time nature of online charging and quota management is a natural fit for pre-paid plans, which are preferred by many subscriber segments, they can also apply to postpaid, such as in Hong Kong where usage caps and notifications are mandated through legislation. In the same vein, the European Union has placed caps on roaming charges, regardless of the subscription method.

Sandvine’s Usage Management product includes multiple features that allow operators to select the right solution for their network. This paper focuses on the online charging feature of Sandvine’s Usage Management product, based on the industry de-facto standard Diameter Gy interface. It also discusses the value of the Gx Usage Monitoring approach, which Sandvine also supports. In a nutshell, the Diameter Gy interface specifications describe the communication framework between the Policy and Charging Enforcement Function (PCEF) and the Online Charging System (OCS). The PCEF enforces policy rules on service data flows, meters their usage, and provides usage reports to the OCS.

However, as operators deploy charging systems, many are finding that success can depend on the specific deployment implementation.

1- Service creation requires a policy evaluation and traffic classification system that is advanced enough to enable innovative and flexible charging models for application layer traffic (e.g., social media, real-time entertainment, cloud storage, etc.), including when the approach is to use Gx Usage Monitoring.

2- For full-on standards-based online charging with an OCS, diameter Gy interface capabilities must be fully matched between the PCEF and OCS to enable cost-effective service creation and avoid revenue leakage.

Simplistic traffic classification and diameter Gy hacks Simplistic Traffic Classification technology, and its inconsistent application by internet transport devices sourced from different vendors, is a root cause for revenue leakage and can limit an operator’s ability to introduce competitive differentiators to the market. On the other hand, incomplete standards support for the Gy interface in any of the solution elements can result in revenue leakage, balance shortfalls, excessive control plane signaling to the OCS, and increased chance of operational issues. A “hack” of the Gy interface standards can also produce unexpected costs related to interoperability and customization, delaying operators from meeting their targeted incremental average revenue per user, which is the whole point of the solution deployment.


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General Opportunities and Challenges Online charging solutions can address the CSP revenue conundrum, but they can also introduce a new series of challenges related to deployment and operation. Operators first require the in-depth business intelligence needed to reliably devise, and then monitor, innovative online charging services. CSPs are also implementing fair use policies that seek to prevent a small minority of users from completely dominating the network’s bandwidth, or as a means to recoup some of that cost. Sandvine’s Global Internet Phenomena Reports, issued twice each year, demonstrate the incredible growth of subscriber data usage.

Whether prepaid or postpaid, when there’s quota involved many service providers need to notify subscribers about their data usage, especially to mitigate bill shock and associated customer support costs when there are overage charges for breaching that 100% threshold. CSPs want to accurately identify critical layer-7 applications for charging and zero-rating. For example, CSPs may want to zero-rate their own sponsored content, or a specific application such as Facebook. Despite the availability of standards, CSPs find that differing standards interpretations between vendors can block the way to consistent deployment and scalability across their evolving networks. Operators also need the ability to audit subscriber data usage and charging to quickly resolve bill disputes. Online charging is about giving subscribers control and choice, which means solutions must track subscriber usage in real time to ensure the right policy is applied at the right time and place, and charged accordingly.

Subscribers respond positively when they have a place they can go to monitor their data usage in real time, top-up quota and even select a specific service plan. Automated self-care portals can save enormous operating costs for CSPs by reducing resources spent on customer plan registration, billing inquiries and customer support.

Figure 1: Sandvine-enabled Automated Subscriber Self-care for Mobile Quota and Roaming

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The Policy Charging and Control Architecture Standards are a good place to start when referencing a method to implement a flexible, future-proof, end-to-end and revenue-generating online charging solution. Specifications laid out by 3GPP detail the concepts surrounding Policy Control and Charging (PCC), which is a framework for flow-based online policy control, enforcement, and charging. While they constitute a great framework that enables service creation, the 3GPP specifications currently only mention use cases based on a 5-tuple set of classifiers for a service flow of source IP address, destination IP address, source port number, destination port number, and flow direction. While this is clearly insufficient for next-generation service creation and enablement, there is no technical reason that prevents the use of the Gy and Gx standards, unmodified, to charge using more advanced classifications and conditions based on application, location (for mobility), and network congestion.

The following high-level diagram shows the PCC architecture in the context of usage measurement and enforcement:

Figure 2: High-level PCC Architecture for Online Charging Services

Quota-based Service Creation – Making it Work FOR You Many operators are reporting a signaling overload upon deploying a centralized decision-making architecture that attempts to manage or charge based on an outmoded view of today’s applications. Consider that a study by Google showed that a simple webpage download of 320 KB resulted in an average of 45 GET requests to around 7 unique hosts per webpage download due to the various sources that comprise a single webpage. In a URL Access Control deployment, if each of those GETs corresponded to a unique URL, then there would be almost 18,000 GET requests (and 36,000 control flows) per gigabyte of HTTP traffic. To put this into perspective, some operators transfer in excess of 137 terabytes (or 137000 gigabytes per 24 hour period)1

1 http://www.fiercewireless.com/europe/story/3uk-data-payload-reaches-137-tb-each-day/2011-11-23

. The behavior of typical users on the popular


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Facebook and YouTube websites is to continuously access multiple embedded applications through simple hyperlink click requests that can translate into tens of unique flows per application access. This model is completely orthogonal to an IP Multimedia-Subsystem (IMS) or walled-garden mechanism, where a service is typically known a priori through SIP signaling.

In addition, “diameter Gy” and “diameter Gx” are not merely boxes to be checked off on a requirements list – interpretation and implementation are critically important for service providers who want to generate revenue with quota-based online charging services.

The PTS Advantage – Bringing PCRF Decision to the Right Place Common PCEFs, such as those found in GGSNs, PDSNs, and the P-GW, can be found satisfying basic requirements such as counting and rudimentary charging for layer-7 traffic. A purely centralized system must face a trade-off between capability and the latency caused by the signaling required for high-speed OTT flow evaluation. Asking a PCRF at every decision point takes time, so the solution must stay limited to meeting the minimum requirements of a PCEF element.

Therefore Sandvine provides PCRF decision functions at the same place where the PCEF resides – on the wire. Sandvine’s distributed, standalone and PCEF-compliant Policy Traffic Switch (PTS) hosts a Traffic Classification technology and Policy Engine that classify and process traffic to enforce policies at the data intersect point in real time. This makes OTT online charging services a reality while allowing the core network to focus on the essential functions of managing address allocation, user plane data routing and handoffs. While the PTS supervises the delivery of service, evaluating the millions of data flows per second associated with OTT traffic, the OCS takes periodic updates from the PTS. The system uses appropriate parameters in the inter-element communication drawn from the Diameter Gy and Gx standards and fine-grained metering to balance signaling performance to the OCS and PCRF in a way that maximizes performance while bringing revenue leakage closer to zero than any Network Policy Control solution available on the market.

The Policy Engine The Policy Engine brings both decision and enforcement to the data intersect point where the PCEF function resides. It distributes per-flow decisions to the place where they must be made millions of times per second, reducing policy-related latency to near zero levels.

The PTS platform is capable of performing real time volume- or time-based metering of traffic using a wide variety of conditions available to the Policy Engine. These conditions include items such as protocol, HTTP fields, attributes about the session or subscriber, time, IP 5-tuple properties, etc. Time is measured based on a configurable in-activity threshold. For example, X bytes over Y time for a given set of conditions.

The top-level PCRF in the control plane and Billing/Operational Support Systems (B/OSS) in the management plane focus on subscriber, session-level transactions and experience anywhere from 100 transactions per second to 50,000 – much lower number than that facing the data plane.


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Figure 3: Relative transaction rates and decision focus for OTT Traffic Management

The key to the solution’s performance and scalability is having the “packet-by-packet, flow-by-flow” evaluations and actions happening at the same place conditions are detected – on the wire. This is not specifically described in the standards because it is an enhancement Sandvine brings that is unique to our brand and technology.

The Traffic Classification technology Using a combination of advanced heuristics, signatures, and measurements, the distributed PTS identifies applications for online charging metering based on volume or time. The PTS also provides functional consistency in 2G, 3G, WiFi, 4G and converged networks while supporting advanced subscriber, location and device identification as conditions in policy. These capabilities power new, differentiated service plans for subscribers, such as mobile applications and the ability to monitor and fine-tune usage plans.

The PTS is precisely designed for the management and supervision of OTT traffic, and can conduct evaluations and measurements at a per-flow level, and apply them to policy that would not be possible with a “centralized-decision” PCEF implementation alone, with no PCRF functionality, due to the latency of waiting for a response from a top-level PCRF at every data flow decision point. The PTS takes full advantage of its position in the network to perform measurements related to everything from data consumption to quality of experience, making them available as part of service plan innovations, enforcement policy, and ready-made, meaningful reports on the performance and quality of the network’s ongoing service plans.

Standards Meet High-Speed, Real-Time Flow Evaluation Sandvine’s PCEF-compliant PTS interacts with an OCS or PCRF using Diameter Gy and Gx signaling in a way that enables, rather than restricts, innovative service plans. For solutions based on Diameter Gy, Sandvine implements capabilities described in 3GPP TS 32.299 based on RFC 3588 - Diameter Base Protocol (DIABASE) and RFC 4006 – Diameter Credit Control Application (DCCA). For solutions based on Diameter Gx Usage Monitoring, Sandvine implements capabilities described in 3GPP TS 29.212 release 9.


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Diameter Gy Implementation The Diameter Gy solution implements the standard Diameter base messages CER/CEA, DWR/DWA and DPR/DPA as well as the Gy interface functional capabilities that include the following messages: CCR/CCA (of types Init, Update and Terminate) using multiple Multiple Service Credit Control attributes and RAR/RAA. The credit control is performed through the allocation of credits with unit reservation to the Sandvine system via usage rating groups, which can be configured using any layer-3 to layer-7 classification policy on the Sandvine platform.

Upon credit depletion or interim quota request, the system has the ability to enforce any action to a Rating Group such as captive portal, shape, allow or block. The PTS can manage volume-based usage so that charges can be applied based on the volume of data transferred (e.g., aggregate, download, upload, per-application, etc.), as well as time-based usage so that charges can be applied based on time spent consuming a specific resource (e.g., aggregate time by session, video streaming time, etc.).

The online charging model that 3GPP technical specification TS 32.299 describes is the partition of the functionality into the service measurement and reporting function by a Charging Trigger Function (CTF) and the control of the credit by an Online Charging Function (OCF), which correspond to the Sandvine PTS (acting in the PCEF role) and the OCS respectively.

Sandvine implements a centralized model for online charging where rating and unit determination are controlled by the OCF and non monetary units (i.e, volume and time units) are exchanged between the CTF and OCF. Rating refers to the translation of the monetary units into non-monetary units as calculated by the unit determination function. The OCF determines the number of non-monetary units that a certain service user can consume based on a service identifier received from the CTF (for a given monetary units).

As per 3GPP TS 32.299, “After checking the service user's account balance, the OCF returns the number of granted units to the CTF. The CTF is then responsible for the supervision of service delivery. Particularly, the CTF shall limit service delivery to the corresponding number of granted units.” This usage checking is coupled with the advanced flow evaluation of Sandvine’s Traffic Classification technology to achieve maximum performance and accuracy.

The standards describe the PCEF concept and the Diameter Gy interface protocol used to enable online charging services, and the PTS meets all requirements of these standards for the purpose of quota-based service creation. Sandvine then goes beyond the standards with advanced features drawn from many years spent on the leading edge of Network Policy Control research. This added-value technology is what truly enables cost-effective OTT service creation with online charging.

Using the Right Tools in the Right Way Inter-element support and vendor interpretation were cited at the beginning of this paper as a particular challenge for the world’s CSPs as they evaluate the approach of various vendors in the market to implementing the Diameter Gy interface standard. Sandvine has successfully completed over 40 interoperability projects with leading PCRF and OCS vendors for the implementation of signaling-efficient, cost-effective, and fully-realized OTT online charging solutions.

One of the most important points to highlight about the Diameter Gy protocol is that it is specifically suited for application-based online charging. It includes a number of protocol tools designed to enable rich layer-7 services in a cost-effective manner while respecting a low tolerance for quota overshoots and revenue leakage. Real-time flow evaluation for OTT online charging requires millions of


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transactions per second at the data intersect point where Sandvine’s PTS performs its policy enforcement and traffic classification magic. But it does not require anywhere near the same degree of signaling intensity between the PCEF-compliant PTS and the OCS. A finely tuned balance for performance and scalability can and must be achieved, making full use of the standard’s communication protocol tools. For next-generation charging, the OCS must support key parameters of the Diameter Gy protocol standard to interoperate with a 3GPP-compliant PCEF that uses advanced functions to enable accurate billing for application-based services.

Sandvine leverages the following key Gy interface communication parameters to optimize the interaction between the OCS and PCEF while achieving an acceptable revenue leakage tolerance of less than 1% (similar to dropped call and access failure targets of less than 1% and 2 – 3% respectively) by proper configuration of the following parameters.

• Granted Service Unit (GSU) • Final Unit Indication (FUI) • Use Service Unit (USU) • Volume Quota Threshold (VQT) • Quota Consumption Time (QCT) • Quota Holding Time (QHT) • Validation Time (VT)

Although not using all of these parameters does not prevent a deployment using Diameter Gy, a fully-realized charging solution based on applications like Netflix and Facebook benefits greatly from having them in play in terms of accuracy, cost, performance and reliability. For next-generation, application-based charging solutions, the OCS system must also support these parameters and scale in tandem with the PCEF element as the network grows.

Sandvine’s unique technology provides an additional advantage to service providers who implement online charging through Diameter Gy. In cases where the OCS is not configured to provide usage grant updates to the PCEF, Sandvine’s PTS supports the ability to receive updates directly from the B/OSS using the Simple Object Access Protocol (SOAP).

Figure 4 shows the general architecture for Sandvine’s standards-based Diameter Gy online charging solution. The Sandvine PTS intersects the subscriber service data plane for supervision of the data service usage. The OCS and PTS exchange Gy messages to regulate the service usage to within the subscriber credit limit. Both the OCS and PTS need to have agreed-upon service rating definitions so that, for example, an email & chat rating corresponds to subscriber service access to SMTP, Yahoo webmail, Goggle mail, Goggle IM, etc. Once the service flow has been detected and mapped to the agreed on service rating definitions, the PTS can request permission to provide service from the OCS, and how much service usage to provide.


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Figure 4: Basic Online Charging Architecture

Figure 5 shows the general sequence of messages for the online charging protocol between the PTS (identified as a PCEF in the figure) and the Service Provider OCS. As can be seen from the sequence in Figure 5, once the PTS detects the subscriber login and has determined their identity through subscriber mapping, it signals the OCS for a request to grant service. Once the PTS has detected the protocols/applications, destinations, and URL services being accessed, it then pings the OCS again for quota for that rating group. Given that the OCS has credit for the subscriber, the OCS then sends the PTS a service quota that corresponds to the subscriber’s rating group/service id. The service quota can be in byte units or time units. The rating group/service Id definition is stored in the PTS policy with an associated identifier and the OCS just sends the identifier so the PTS knows the service group that is being metered. Note that the rating groups/service Id definitions need to be coordinated between the PTS and the OCS.

This enables some unique value in the Sandvine Solution – while less sophisticated systems generally use only simple 5-tuple classification and simple URL detection, Sandvine provides the ability to define, for example, social media applications like Facebook and Twitter.

It is important to highlight that Sandvine implements a real-time interface for online charging through Diameter Gy. This means the PTS is perpetually reading the byte-by-byte nature of data flows in real-time and updating the OCS on a periodic basis using the sophisticated levers of the interface. At the same time the PTS is collecting fine-grained business intelligence that is fed into operational and strategic reporting platforms for complete awareness of network and subscriber behavior yesterday, today, and projected into tomorrow.

This responsive system allows, for example, real-time updates from the OCS for situations where a subscriber replenishes their quota through a self-serve portal.

Once the PTS knows the subscriber, their associated service rating and their granted quota, the PTS supervises the service usage up to the granted quota. Upon reaching the granted quota limit, the PTS may stop2

2 The standards imply stopping of service however this may not be the best subscriber experience. The Sandvine PTS offers flexible enforcement options, such as shaping, while waiting for further quota. If service is not stopped, the PTS continues accumulating usage for reporting back to the OCS once the next quota grant is received.

service and inform the OCS of the actual used service (not the granted quota limit) so that the monetary value for the used service can be deducted from the subscriber’s available credit. If there is credit remaining, the OCS then updates the PTS with the updated granted quota. This continues until the subscriber stops using the service and logs out or the subscriber runs out of credit,


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in which case the subscriber out-of-quota policy is invoked (shown as shaping in Figure 5). Note that the final quota granted when credit is about to be exhausted can be a final quota with policy on exhaustion so that there is no danger of usage exceeding available credit.

The rating group/service Ids that the OCS provides to the PTS define the types of service for which the subscriber is metered. This can be vary from total raw byte count or byte count for certain application classes to allowing and measuring only access to certain URLs or IP/subnet destinations. The subscribers’ service plans will define their authorization to rating groups or service Ids.

Figure 5: Online Charging Service – Service Sequence


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Diameter Gx Implementation Quota-based online charging implemented through Gx Usage Monitoring is less-capable but more streamlined in terms of deployment and operation. As it does for the diameter Gy use case, for Gx Usage Monitoring Sandvine brings fine-grained metering control and layer-7 application awareness with both service-level and session-level monitoring. The solution supports all types of volume counting, including total bytes, sent bytes, and received bytes.

Sandvine supports the typical standards-based attribute value pairs (AVPs) called out in the 3GPP technical specifications (e.g., Charging-Rule-Name AVP, Charging-Rule-Base-Name AVP) that reduce signaling and take advantage of the PTS element’s on-wire decision capability for metering accuracy in layer-7 application charging. Sandvine also supports custom- and vendor-specific attributes that enable unique use cases with subscriber notification such as advice of charge and promotional content with variable URLs. This comes in handy in some deployments in which the PCRF passes proprietary dynamic parameters relevant to some PCC rules (e.g., promotional URLs or subscriber categories). With this capability, operators with advanced and customized use case requirements achieve significant cost efficiencies by cutting down on network design efforts and shortening deployment test cycles.

The solution is implemented through monitoring keys resident on the PCRF that take the metered usage data from the PCEF. The USU and GSU values, also used in the Diameter Gy implementation, are employed for communicating usage to the PCRF, and grants to the PCEF and, ultimately, the subscriber. Figure shows a logical diagram of Sandvine’s implementation of the Gx Usage Monitoring solution.

Figure 6: Online Charging Service – Service Sequence

Comparing Charging Approaches – Gy vs. Gx A side-by-side comparison of the two available charging approaches using the Diameter interface can shed light on the suitability of each method for a particular situation.

The PCEF, the OCS and Diameter Gy The Diameter Gy standard is described by 3GPP TS 32.299, which specifies communication between the PCEF and OCS.

Challenges The challenges with Diameter Gy all surround the issue of standards interpretation and the overall approach to stateful Network Policy Control that a CSP elects to pursue. Just having the Diameter Gy stack available and working on some level is insufficient to make services work. Operators must ensure


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that PCEF, OCS and potentially PCRF vendors have adequate support for the applicable features of the 3GPP policy control and online charging standards to realize the use cases they are seeking. The solution complexity is also higher, typically requiring more investment in equipment (OCS) and a longer deployment and test cycle time.

Advantages The greatest advantage of utilizing the online charging approach, for prepaid services, is that it provides a session-based method to accurately track volume and time. For both prepaid and postpaid offerings, it is the right protocol to enforce usage cap limits on subscribers and enable more modern charging options with advice of charge, toll-free data, notifications, and quota limited add-ons and bundles. The use of Diameter Gy signaling, when properly deployed, facilitates real-time rating and charging of traffic usage to the subscriber’s balance. The Diameter Gy interface can run independently even without a PCRF. CSPs who are using PCRF systems already do not have to reconfigure or deploy additional elements, and CSPs who do not see a current need for a PCRF in their network are not obligated to purchase one.

Usage management through Diameter Gy signaling is extremely accurate, alleviating many issues arising from exceeding quota cap limits or thresholds. The responsive nature of the credit control system and the core functionality enabled by Gy interface signaling ensures that subscribers are accurately charged in the business transaction according to the limits of their quota in the OCS. The real-time nature of Gy signaling allows operators to communicate threshold notifications to subscribers at multiple quota depletion points (i.e., 60%, 80%, 90%, 100%). This ability to support notification translates directly into several critical functions:

• Bill shock prevention • Up selling bolt-ons and bundles • Enabling personalization and targeted promotions • Rea-time advice of charge • Promotional content • Tethering plans

The PCRF and Gx Usage Monitoring Usage Monitoring over the Diameter Gx interface is a feature of 3GPP TS 29.212 Release 9. It reports usage volume information strictly through a Diameter Gx session between the PCEF and PCRF.

Challenges As a relatively simplified concept of online charging, usage monitoring over Gx is only limited to volume (i.e., bytes) reporting. Reporting usage for time quota is not natively supported over the Gx interface. The Gx interface does not support many of the levers and controls that are intrinsic to the Gy interface, as described in “Using the Right Tools in the Right Way” on page 7. The Gy interface also supports multiple granularities of managing subscribers’ quota at the charging key (also known as the rating group) level or at the service level at minimal signaling load. On the other hand, the Gx interface only supports one level through the utilization of monitoring keys for reporting volume usage of the data session or the service data flows.

As a result, for deployments that do not benefit from Sandvine’s on-wire decision capability, which provides fine-grained metering for maximum revenue retention, to avoid a signaling overload non-Sandvine solutions must reduce the frequency of usage updates to the PCRF. This results in a higher likelihood of revenue leakage and quota cap breaches. The operator is also likely to incur


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customization costs for enabling out-of-standards proprietary support of time quotas on the PCRF and the PCEF if this is a desired feature.

Advantages The main advantage of this approach is that it can reduce the total cost of ownership for a solution if a CSP already has deployed a PCRF, with reduced deployment time and associated costs. To put it simply Gx Usage Monitoring is cheap and easy to implement, and Sandvine’s Policy Engine and Traffic Classification technology help offset the tradeoffs associated with taking this approach.

Use Cases - Diameter Gy vs. Diameter Gx The following table shows the breakdown of online charging use cases enabled by both approaches, as delivered by Sandvine:

Table 1: Online Charging Use Case Support – Diameter Gy vs. Diameter Gx

Use Case Diameter Gy

Diameter Gx

Volume

Time

Events

Single-level threshold notification

Multi-level threshold notification

Rating engine support

Service Id support Report different protocols within one rating group

Less than 2% revenue leakage for OTT charging

Deployment simplicity

Conclusion Sandvine’s implementation of quota-based online charging using Diameter achieves the optimum balance between the OCS and PCEF, or PCRF and PCEF, depending on the desired use case, to make accurate and profitable OTT charging services a reality, as shown by the example presented by Figure 7. This example dramatically increased ARPU for a particular service provider and put it three years ahead of its closest competition, and Sandvine can enable it in any mobile network using either Diameter Gx Usage Monitoring or online charging through Diameter Gy.


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Figure 7: Sandvine-Enabled Online Charging Service

Again, as operators deploy charging systems, success will depend on the specific deployment implementation.

1- Service creation requires a policy evaluation and traffic classification system that is advanced enough to enable innovative and flexible charging models for application layer traffic (e.g., social media, real-time entertainment, cloud storage, etc.), including when the approach is to use Gx Usage Monitoring.

2- For full-on standards-based online charging with an OCS, diameter Gy interface capabilities must be fully matched between the PCEF and OCS to enable cost-effective service creation and avoid revenue leakage.

A poor Traffic Classification technology is a root cause for revenue leakages and can limit the operator’s ability to introduce competitive differentiators to the market. On the other hand, incomplete standards support for the Gy interface can result in revenue leakage, balance shortfalls, excessive control plane signaling to the OCS, and increased chance of operational issues. A “hack” of the Gy interface standards can also produce unexpected costs related to interoperability and customization, reducing the CSP’s ability to increase average revenue per user (ARPU), which is the whole point of the solution deployment.

Approaches such as Diameter Gx Usage Monitoring are appropriate in the right context as long as the limitations are deemed acceptable, while Diameter Gy is the standards-based interface specifically designed for application-based online charging. Sandvine’s PTS, with its distributed decision capability, and complementary Policy Engine and Traffic Classification technology, is designed specifically for the high-transaction flow evaluation that enables next-generation online charging, whatever the chosen approach.

Copyright ©2013 Sandvine Incorporated ULC. Sandvine and the Sandvine logo are registered trademarks of Sandvine Incorporated ULC. All rights reserved.

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