Application delivery controllers and their roles in …...APPLICATION DELIVERY CONTROLLERS AND THEIR ROLES IN THE MOBILE NETWORK How operators can leverage ADCs to deploy scalable,

APPLICATION DELIVERY CONTROLLERS AND THEIR ROLES IN THE MOBILE NETWORKHow operators can leverage ADCs to deploy scalable, virtualized networks and enable new business models

February 2014

Prepared by Signals Research Group

Paper commisioned for Citrix

Signals Research Group has researched and documented its views on the various roles that ADCs can play in next-generation mobile networks. As the sole authors of this paper, we stand behind the analysis that it contains. In addition to providing consulting services on wireless-related topics, Signals Research Group is the publisher of the Signals Ahead research newsletter (www.signalsresearch.com).

www.signalsresearch.com

Page 2February 2014


Application Delivery Controllers and Their Roles in the Mobile NetworkHow operators can leverage ADCs to deploy scalable, virtualized networks and enable new business models

1.0 ExecutiveSummaryAs the first wave of LTE deployments nears completion in many markets around the world, operators are turning their focus to delivering innovative services that leverage the new features possible with LTE networks. To monetize these networks, operators need a unified service archi-tecture, with service orchestration capabilities, to create subscriber-specific services. Therefore, the focus of mobile network evolution should be enabling a scalable and reliable unified service architecture.

Virtualization and cloud services are important building blocks for creating a service architecture with orchestration capabilities. Virtualization is already taking hold in mobile services networks, enabling operators to introduce new services. The evolution towards virtualized mobile networks will continue over the next few years as operators embark on Network Function Virtualization (NFV) and Software Defined Networking (SDN) in mobile core and transport networks.

This whitepaper explores the evolution and role of the Application Delivery Controller (ADC) in current mobile networks. The ADC started as a load balancer and traffic manager for creating scalable server farms, and expanded to a number of services, including SSL offload and compres-sion meant to accelerate application performance. As a global traffic management entity, ADCs play a major role in service orchestration in data centers. ADCs bring these features to mobile networks to enable scalable 4G network deployments.

A scalable control plane architecture is a critical aspect of service delivery. ADCs support traffic management and load balancing of major control plane protocols, such as Diameter and SIP, making ADCs a key component of the control plane infrastructure. Diameter is used extensively in LTE networks for signaling between various elements to support subscriber verification, policy control, charging and other OSS functions. The load balancing and traffic management capabili-ties of ADCs play a key role in deploying scalable Diameter infrastructure.

SIP is the control protocol for Voice over LTE (VoLTE)/IMS, used to deliver next generation voice and enhanced services such as RCS. VoLTE is the final phase in the transition to an all-IP network. Voice, messaging and RCS are part of most operators’ service offerings. The role of ADCs in SIP delivery is crucial in creating scalable and reliable VoLTE/IMS networks.

ADCs can play a major role in enabling new business models in the evolution of mobile networks. Given their central role in the traffic management of service components in the mobile services network, ADCs can evolve into a unified service delivery platform. Such a platform enables operators to offer personalized services through dynamic service chaining.

Finally, MVNOs and M2M services have become an important part of an operator’s business model. Many operators are also partnering with OTT service providers to be part of the OTT value chain. ADCs can play a significant role in supporting a large number of MVNOs and M2M service providers in a scalable fashion. ADCs, or ADCs in virtualized form, can support the key features such as multi-tenancy, traffic isolation and personalized service chaining neces-sary to support MVNO, M2M and OTT service providers.

Monetization requires a network

architecture flexible enough to

support a diverse range of services.

This whitepaper explores the role of

the Application Delivery Controller

(ADC) in mobile networks.

Page 3February 2014



TableofContents1.0 Executive Summary ………………………………………………………………………………………………………………………………………2

2.0 The All IP Mobile Network Evolution …………………………………………………………………………………………………4

2.1 New Service Opportunities ………………………………………………………………………………………………………………… 42.2 The Requirements …………………………………………………………………………………………………………………………………… 42.3 Key Enablers ……………………………………………………………………………………………………………………………………………… 52.4 ADCs: Playing Many Roles in Mobile Networks ……………………………………………………………………………6

3.0 Mobile Services Network: Creating a Unified Service Architecture ……………………………………………8

3.1 ADCs as a Unified Service Delivery Platform …………………………………………………………………………………93.2 Application Aware SDN ……………………………………………………………………………………………………………………… 10

4.0 ADCs as Diameter Load Balancers: Enabling a Scalable Control Plane …………………………………… 11

4.1 Diameter Products ……………………………………………………………………………………………………………………………… 114.2 Architecture Options …………………………………………………………………………………………………………………………… 124.3 Home Subscriber Server (HSS) Load Balancing …………………………………………………………………………… 124.4 Policy Control and Charging Rules Function (PCRF) Load Balancing …………………………………… 12

5.0 VoLTE/IMS Networks: Delivering Scalable SIP services ……………………………………………………………… 14

5.1 SIP Scalability Considerations …………………………………………………………………………………………………………… 145.2 Session Border Controller (SBC) Load Balancing ………………………………………………………………………… 145.4 Application Servers (AS) Load Balancing ……………………………………………………………………………………… 15

6.0 External Service Providers: Enabling New Business Models ………………………………………………………… 16

6.1 Mobile Virtual Network Operators (MVNO) ……………………………………………………………………………… 166.2 Machine-to-Machine …………………………………………………………………………………………………………………………… 166.3 OTT Service Providers ………………………………………………………………………………………………………………………… 18

7.0 Conclusions ………………………………………………………………………………………………………………………………………………… 19

IndexofFiguresFigure 1. The ADC Evolution ……………………………………………………………………………………… 6

Figure 2. Traffic Steering for Different Services …………………………………………………………… 8

Figure 3. Service Chaining ………………………………………………………………………………………… 9

Figure 4. Application Aware Networking with ADCs ………………………………………………………10

Figure 6. SIP ADCs in VoLTE/IMS ………………………………………………………………………………… 15

Figure 7. The M2M Cloud with ADCs …………………………………………………………………………… 17

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2.0 TheAllIPMobileNetworkEvolutionFor mobile operators the shift to all-IP networks is a major transition. One of its primary objec-tives is to provide additional network capacity and a better user experience. Unfortunately, in many cases operators are running a bit pipe business model. They are not part of the majority of services delivered over mobile data networks – the app store, social media and online video value chain.

2.1 NewServiceOpportunitiesThere are several mechanisms for operators to deliver their own value; they can:

➤➤ Offerpersonalizedservicestosubscribersandenterprises. For example, customers with a family plan may want to subject phones for teenagers with parental controls. Different group of employees within medium enterprises may require different security policies. Personalized services with subscriber control can become part of a new set of service offers.

➤➤ Becomeaplatformforthirdpartyoperators.An even bigger opportunity is to position the network as a platform for third party operators to deliver new types of services to their subscribers. Operators can open part of their network to MVNOs to run their applications directly. This would enable new MVNO models, expanding upon the current model based on customer segment expertise.

➤➤ Develop solutions and partnerships with Over-the-Top (OTT) service providers.Although mobile operators have been in a dilemma regarding whether they should treat OTT services as friend or foe, lately it appears that a number of operators have decided to friend OTT service providers through partnerships. New service models can be created based on sponsorship and user experience.

➤➤ DeployMachine-to-Machine(M2M)services.M2M services are spread over many verti-cals, such as healthcare, security, fleet management and utility with the M2M business model consisting of a combination of in-house, partner solutions and third party MVNOs. Operators can target new services to expand the M2M market.

2.2 TheRequirementsMobile networks are not designed for operator-customers to access network resources with flex-ibility, while operators cannot dynamically program their networks to offer personalized services.

For example, as MVNOs, M2M and OTT service providers launch their services, they require access to billing, policy control and value-added-service (VAS) platforms. In some cases, they require the ability to program the mobile network to meet service requirements. Since these capabilities do not exist, the mobile network architecture becomes a chokepoint for external service providers.

Therefore, mobile wireless network evolution must meet several key requirements:

➤➤ NetworkProgrammability:A programmable network should offer the flexibility to meet requirements of a diverse set of services, third party applications and partners. Additionally, service exposure through integrated APIs is required to provide external applications a conduit to access and configure network functionality more efficiently.

The current mobile network

architecture becomes a chokepoint

when it comes to supporting the

external service providers.

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➤➤ Multi-Tenancy:As operator business models evolve to partner with MVNOs, M2M and OTT service providers, the network architecture must evolve to support a large number of service providers. Therefore, supporting multi-tenancy becomes a major requirement to enable traffic isolation, differentiated policy control and security. More importantly, it should provide for each provider a differentiated service offering.

➤➤ ServiceChaining: A critical technology for offering personalized services, service chaining refers to customized service processing for different subscribers, who may be consumers, enterprises or service providers. Additionally, it should be possible for customers to create service chains through a service creation environment.

➤➤ Network Scalability: Operators require the ability to scale their network in relation to the growth of services and revenues. Current network deployments are planned with large subscriber capacity even before subscribers get on the network. A scalable solution should allow for the granular upgrade of network capacity based on demand.

➤➤ TrafficManagement:One of the major issues in mobile networks today is the lack of opti-mized traffic management. Typically, mobile networks are deployed regionally with each region operating as an autonomous network. Capacity is not shared optimally within a region let alone across geographic regions. Optimized traffic management is essential to reducing OpEx and CapEx.

2.3 KeyEnablersEven as many operators are completing their first phase of LTE roll-outs, mobile operators have begun to turn their focus on service agility. The goal is to support a diverse set of services devel-oped internally or externally, with CapEx and OpEx efficiency. These key enablers are designed to support their goals:

➤➤ Orchestration: Orchestration includes service orchestration (automated service creation) and resource orchestration (infrastructure scaling) Orchestration is crucial for offering personalized services as well as creating scalable networks. The mobile services network has grown to support a large number of service platforms geared towards different services. Service orchestration in conjunction with virtualization and emerging standards will enable the creation of new services by integrating diverse set of service platforms into a unified service architecture.

➤➤ Virtualization: Virtualization is already transforming wireless networks. Through virtual-ization, operators can introduce new services rapidly with CapEx and OpEx efficiencies. Virtualization enables Infrastructure-as-a-Service (IaaS) and multi-tenancy paradigms for large-scale deployments of MVNOs, M2M and OTT services. Network Function Virtualization (NFV) will transform radio and core networks into software elements that can run in a cloud environment. Although standards-based NFV is a few years away, pre-standard NFV components are expected to be deployed as early as next year.

➤➤ SoftwareDefinedNetworking(SDN): Applied to the mobile network context, SDN seeks to provide integrated control over the RAN, core, services and transport networks. As a framework that controls the entire network infrastructure, SDN can provide the business intelligence that is needed to target services delivery to subscribers.

➤➤ ApplicationAwareNetworks:This refers to a dynamic service architecture in which applica-tions can indicate required infrastructure resources and behavior. A bi-directional feedback

Page 6February 2014



loop between applications and the network creates a paradigm for these elements to interact with each other to meet the required customer experience. As an example, new compute resources can be made available to an application to meet surging traffic with the data path traffic automatically routed to these new resources.

2.4 ADCs:PlayingManyRolesinMobileNetworksApplication Delivery Controllers (ADCs) have been a key building block in the evolution of the data center through its central role in enabling virtualization and cloud services and supporting deployment of very large server farms. At its core, ADCs provide Layer 4 through Layer 7 traffic management and load balancing. ADCs, which began with HTTP load balancing for server farms, are evolving to play additional roles (reference Figure 1), which are applicable in mobile networks.

In mobile networks, ADCs can:

➤➤ Optimize both SIP and Diameter traffic. The ADCs heritage of HTTP-based load balancing has been extended for a variety of mobile protocols, particularly Diameter and Session Initiation Protocol (SIP). Diameter is at the heart of LTE networks crucial for service delivery while SIP is the signaling protocol for VoLTE/IMS networks.

➤➤ Serveasaunifiedservicedeliveryplatform. As the ADC is in the path of signaling and user plane traffic, it is best suited as a common service fabric to orchestrate across a diverse set of application platforms.

➤➤ Coordinatewiththeunderlyingnetworktoenableanapplicationresponsivenetwork. Given most Layer 4 through Layer 7 application traffic passes through the ADC, it is the most application aware network element. This awareness can be leveraged to communicate with the underlying network regarding application health and performance.

➤➤ Enable service orchestration and chaining. In the context of virtualization, application aware ADCs integrated with cloud management stacks can enable agile service orchestra-tion to meet application requirements.

The ADC is the most application

aware network element.

Figure 1. The ADC Evolution

HTTP Load Balancing

Control Plane Load Balancing

(Diameter & SIP)

Unified Service Delivery

(Service chaining and

Personalization)

Application Responsive Networking

Virtualization & Multi-tenancy

Source: Signals Research Group

Page 7February 2014



➤➤ Enablenewbusinessmodels.Virtualized, multi-tenant ADCs with service chaining are well suited to execute new business models based on partnerships with MVNOs, M2M service providers and OTT service providers.

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3.0 MobileServicesNetwork:CreatingaUnifiedServiceArchitectureThe mobile services networks lack a unified service delivery architecture since most platforms operate in separate silos with their own management. These platforms duplicate functions, such as traffic management, while their use in network architectures makes it difficult for new applica-tions to be inserted without manual intervention and significant advanced planning.

A unified service architecture would shorten the timeframe for operators to innovate new busi-ness models. It would also provide a platform to flexibly add applications while allowing for a customized path for each subscriber across these applications, depending on user profile, rate plan or operator policy. For a dynamic and scalable service model, a unified architecture should meet the following requirements:

➤➤ Integrate with S/Gi-LAN and datacenter applications. As a service fabric on which S/Gi-LAN and data center applications are integrated, a unified platform can integrate many common functionalities (traffic management, health check, high availability, etc.) currently implemented by each network element, leaving the network element to perform its intended functions most efficiently. It can provide network programmability through APIs for external entities to create new application templates.

➤➤ Supportpersonalizedservices.Personalized services are created by steering traffic through different network elements. As shown in Figure 2, a subscriber might wish to invoke a parental control service for one of the phones in his or her service plan. When a bearer is established for that phone, the traffic must be steered through a parental control function. Alternatively, invoking a video streaming service may result in traffic being steered through a video optimization function.

Figure 2. Traffic Steering for Different Services

LTENetworks

P-GW

PCRF Orchestration

Unified Services Platform

ParentalControl

Internet EnterpriseOTT

Video Service

VideoOptimization

ViPNSever


Page 9February 2014



Service chaining is the extension of traffic steering by extending steering traffic through multiple network functions in a pre-defined order to create a new value added service. As shown in figure 3, service chaining for an iOS or Android smartphone user requires traffic to be routed through web proxies, a Firewall and NAT servers. When an OTT video on demand service is invoked, a connectivity path through the video optimization server and firewall are required.

➤➤ Providedynamicserviceandresourceorchestrationforserviceslifecyclemanagement. Service orchestration creates new virtual network functions and enables new service chains for personalized service delivery. Resource orchestration allows dynamic and elastic capacity expansion to meet application demands. It also involves moving virtual network function instances in the cloud to manage capacity across data centers.

3.1 ADCsasaUnifiedServiceDeliveryPlatformADCs are uniquely qualified to meet the requirements for a unified service delivery platform:

➤➤ Theyalreadyperformserviceandresourceorchestration.Since most ADC platforms in a physical or virtual form are already integrated with major cloud management stacks, ADCs can play the role in the provisioning and scaling up/down of new application templates. When new instances of virtual network functions are created, ADCs add them dynami-cally to traffic management clusters and provide Layer 4 through Layer 7 load balancing. Additionally, ADCs perform resource orchestration through dynamic and elastic expansion of compute and storage capacity.

➤➤ They collect valuable analytics on applications in terms of performance and servicequality. Analytics can be used by management stacks to maintain high availability by routing traffic around applications that are overloaded or failing.

➤➤ Theyhaveevolvedtosupporttrafficsteering,allowingoperatorstoofferpersonalizedservices.The traffic steering capability serves as the building block for implementing service chaining. Over time, ADCs can act as the central traffic controller in the mobile services network for steering the traffic through different network elements in a pre-defined order. An example is shown in Figure 3. The web page retrieval is steered through a web proxy (where user quota may be specified), followed by NAT and the firewall. On the other hand, the initiation of the IMS service should result in the establishment of a connectivity path to IMS networks through the Session Border Controller (SBC).

ADCs can also collect valuable

analytics on applications in terms

of performance and service quality.

Figure 3. Service Chaining

LTENetworks

Internet

Firewall

PCRF Orchestration

Unified Services PlatformP-GW

OTT Video Service

NATWeb & Video

Optimization


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3.2 ApplicationAwareSDNApplication aware SDN is an emerging concept that puts applications at the center of the network. It is a holistic approach to service delivery designed to make the underlying network more responsive to application requirements. Application aware networking requires a node that can monitor applications and understand their requirements and communicate them to the underlying network. The ADC’s role in traffic management and service orchestration provides them visibility to applications. In fact, ADCs already provide enhanced analytics regarding appli-cation performance such as bandwidth and latency.

The application aware networking builds on top of SDN. SDN is designed to bring network programmability and integrated control to the underlying networks at Layer 1 through Layer 3. ADCs can play the role of application aware controllers that interface with SDN controllers to communicate application requirements to underlying networks. ADCs can also interact with management stacks to provide feedback on application requirements that could result in adding more compute capacity or rebalancing server load.

It is quite conceivable to visualize the integration of the ADC and the SDN controller, creating what could be called an Application Defined Controller. The integration will enable two-way feedback between applications and the networks enabling rapid response to issues such as network congestion and network outage.

In the mobile context, application aware networking requires interfacing with the underlying wireless networks (reference Figure 4). Additionally ADCs are enhanced to interface with policy control infrastructure for service personalization.

ADCs can play the role of application

aware controllers that interface with

SDN controllers to communicate

application requirements.

Figure 4. Application Aware Networking with ADCs

OptimizationServers Applications

3G/4G Networks

TransportNetworks

Firewall

PCRF SDN Controller

NAT

Unified Services Platform(Application Aware)

NFV ManagementStack

(Service Orchestation)





4.0ADCsasDiameterLoadBalancers:EnablingaScalableControlPlaneAlmost every network element in LTE/IMS networks, except perhaps for the eNodeB, acts as a Diameter client, Diameter server or both. Every session and bearer establishment involves multiple Diameter transactions. Therefore, reliability and scalability of Diameter messaging is central to LTE service delivery.

Although Diameter routing can be implemented in a peer-to-peer fashion between network elements, the enormity of Diameter signaling in LTE networks makes that scenario a nightmare. Instead, operators are building Diameter infrastructure for interconnecting network elements involved in Diameter signaling.

4.1 DiameterProductsThere are two major classes of Diameter products required to handle the current and future growth of Diameter traffic. First is Diameter Signaling Controllers (DSCs), formalized by 3GPP as Diameter Routing Agents (DRA). DSCs support core Diameter message routing similar to core routers in the IP transport backbone. They eliminate the need for mesh connectivity among network elements since the DSC will retain network state for each Diameter session.

The other class of Diameter products is the Diameter Load Balancers (LB). Diameter LBs are installed at the edge of the Diameter routing infrastructure as shown in Figure 5. Similar to IP edge routers, Diameter LBs provide a number of enhanced functions crucial to control plane service delivery. The Diameter LBs implement key functions such as load balancing, topology hiding, health check and high service availability.

ADCs, with their load balancing and traffic management features, are naturally suited to play a significant role in the Diameter control plane. Current ADC products, which already support load balancing of messaging protocols, such as Diameter, can be incorporated as Diameter LBs in LTE networks providing scalability for PCRF, OCS and HSS to support the massive number of connections expected from smartphones and M2M devices. The ADCs also present a single virtual IP address to the Diameter routing core, irrespective of the number of network elements behind the LB. Therefore, ADCs let operators add or delete capacity without requiring a massive reconfiguration of other network elements.

ADCs let operators add or delete

capacity without requiring

a massive reconfiguration of

other network elements.

Figure5.DiameterRoutingInfrastructure

HSSDB

HSS-FE HSS-FE

MME

MME

S&P-GW

S&P-GW

PCRF OCS

OCSPCRF

DiameterLB

DSC DSC

DiameterLB

DSC





4.2 ArchitectureOptionsThere are different architecture options for deploying ADCs in Diameter infrastructure. In large Tier 1 networks, extensive infrastructure with DSCs in the core and ADCs as Diameter load balancers is required to support a network spread across a large region or entire country. The ADCs are deployed at the edge to enable operators to upgrade network element capacity without reconfiguring the entire routing plane. In smaller Tier 2 and Tier 3 networks, extensive infra-structure with DSCs may be overkill. In smaller networks, mesh connectivity can be established between the network elements with ADCs performing load balancing/traffic management func-tionality. Eventually, ADCs can add routing functionality as well.

Another emerging architecture is virtualized DSCs and virtualized ADCs. The control plane is expected to be the starting point for virtualization and the evolution to cloud. Key control plane elements, such as PCRFs, OCS, and CSCFs, are the initial candidates for virtualization. Virtual-ized ADCs provide load balancing among virtualized network elements. Virtualized ADCs can also provide the orchestration function for the control plane to increase capacity or optimize traffic management. Control plane orchestration in virtualized mobile core networks is crucial for delivering high availability and scalability.

4.3 HomeSubscriberServer(HSS)LoadBalancingAs a unified data repository across 3G, LTE and IMS networks, the HSS/AAA infrastructure availability and scalability is a standard requirement for service delivery. HSS provides authenti-cation and authorization functionality. Typically, the HSS/AAA architecture employs distributed nodes, which may or may not be fully replicated. The HSS accepts requests from network nodes such as the MME, PCRF and SGSN for authentication and subscriber/QoS profile download.

When the HSS is fully replicated across multiple nodes, the ADCs, which acts as a load balancer, selects the HSS typically based on load conditions. Once selected, the load balancer must main-tain the mapping between the user and the HSS node. If the HSS is not replicated, the ADCs requires implementation of the Subscription Location Function (SLF), which is defined in 3GPP architecture, to map the subscriber to a specific HSS where the subscriber profile is maintained.

4.4 PolicyControlandChargingRulesFunction(PCRF)LoadBalancingThe architecture evolution for LTE core networks indicates an increased role for PCRF in session processing. For example, as operators add services, such as VoLTE, PCRF interaction is expected to increase substantially since every VoLTE call requires a request from IMS to the PCRF to allocate resources in the LTE network. Additionally, the long lived nature of LTE data sessions requires increased PCRF capacity. Therefore, operators are expected to deploy extensive PCRF infrastructure with PCRF clusters in each region.

PCRF load balancing is required for traffic management and capacity utilization. The PCRF load balancing requires implementation of PCRF binding where a PCRF is selected when a new session request is initiated from the user. Without ADCs, the PCRF binding functionality must be implemented in every client, resulting in increased complexity in the LTE core network. The ADC can perform PCRF binding based on operator specific load balancing polices, such as geographic location, load and specific PLMN domains.

Once PCRF binding is performed, the ADCs must maintain stateful mapping between the user and the PCRF. Stateful mapping is required so that all Diameter messages that originated

Virtualized DSCs and ADCs are

another emerging architecture trend.




as part of the same session are routed to the same PCRF. The ADCs that maintain mapping between the user and the PCRF inspects AVPs in Diameter messages to route traffic to the correct PCRF server.




5.0 VoLTE/IMSNetworks:DeliveringScalableSIPservicesVoLTE deployments will gain momentum as operators transition away from 3G voice services. Deploying VoLTE represents a paradigm shift to packet-based voice using SIP and IMS plat-forms. The IMS architecture presents certain challenges. First and foremost, operators have to deploy a scalable and reliable, distributed IMS platform. Secondly, the scalable architecture must enable gradual upgrade of VoLTE capacity as subscribers transition from 3G voice to VoLTE.

Therefore, load balancing is a major requirement for VoLTE service delivery. ADCs can play a significant role in enabling SIP/Diameter load balancing to deliver optimized network perfor-mance for the IMS platforms. In addition to load balancing, ADCs can perform integrated health monitoring and eventually offload important capabilities, such as security and compres-sion, from IMS network elements.

5.1 SIPScalabilityConsiderationsAlthough SIP shares a lot in common with HTTP, there are important SIP characteristics that must be accommodated by SIP load balancers. SIP sessions last as long as voice calls, unlike HTTP sessions which are completed in a relatively shorter time period. Further, unlike HTTP, where each request can be handled by a different server, once the SIP registration is performed, network elements, such as the SBC and Application Servers, are selected to handle sessions from the user. The same set of network components must be selected for subsequent session establishment.

In order to achieve scalability, SIP load balancers may also combine multiple SIP sessions over a single TCP connection. In this scenario, SIP load balancers must perform many to many mapping between SIP sessions on either side of load balancing. This scenario means receiving SIP sessions over multiple TCP connections from multiple entities and aggregating them over a single TCP connection towards a network element.

5.2 SessionBorderController(SBC)LoadBalancingSBCs are one of the key components in the IMS/VoLTE network. A SIP-aware ADC (refer-ence Figure 6) enables the deployment of large scale SBC clusters with a single virtual IP address access for SIP signaling. SBC load balancing allows operators to scale SBC capacity gradually without committing large upfront capacity, meaning that SBC capacity can be added or deleted depending on load requirements without reconfiguring other network elements.

SBC load balancers are only involved in the selection of SBCs, either at SIP registration or at SIP session initiation. In one variation, the load balancer assigns a SBC to a specific subscriber upon SIP registration. After SIP registration, all of the SIP messages are sent to the assigned SBC. This option is suitable for A-SBC, which is deployed in front of the access network.

A SIP aware load balancer is essential

for a scalable deployment of SBCs.




In the second variation, the load balancer may assign the SBC for a specific SIP session upon session initiation. All the messages related to that SIP session are sent to the assigned SBC. Subsequent SIP sessions from the same subscriber may result in the assignment of a different SBC. This option is suited for I-SBCs which perform inter-domain routing.

ADC-based SIP load balancers can evolve to offload certain compute intensive functions from SBCs. These functions include SIP message integrity protection, optional encryption and SIP message compression. Offloading of these compute intensive functions enables SBCs to focus on their core function as application level gateways.

5.4 ApplicationServers(AS)LoadBalancingThe case for deploying ADCs as application servers depends on the capacity and scalability requirements of a specific application.

The case for deploying ADCs to perform load balancing for application servers depends on the capacity and scalability requirements of a specific application. ADCs are most suited for deploy-ments of large scale application servers, where ADCs can provide clustering, traffic management and geographic redundancy.

A Telephony Application Server (TAS) is an example that would require ADCs. TAS handles all signaling related to voice services, including supplementary and regulatory services. S-CSCFs essentially hand over the call to the TAS after initial authentication. While S-CSCF can perform TAS selection separately, it does not have a global view of the signaling load on the TAS cluster. Therefore, TAS merits load balancing on its own. The load balancer can act as single point of contact for initial requests and assign a TAS for each session. Once assigned, the S-CSCFs can communicate directly with the TAS for subsequent signaling.

ADC-based SIP load balancers can

evolve to offload certain compute

intensive functions from SBCs

Figure 6. SIP ADCs in VoLTE/IMS

HSS-FE

A-SBC

SIP ADC SIP ADC

A-SBC

A-SBC

S-CSCF

S-CSCF

AS

AS

I-SBC

I-SBC

LTENetworks

IMSDOMAINSecurity

Association





6.0ExternalServiceProviders:EnablingNewBusinessModelsThe evolution of mobile operators to a wholesaling model supporting a large number of other operators has implications for the network architecture. A large number of external operators will be integrating into an operator’s network at various interface points, so the network architecture has to support efficient integration. This level of integration adds new requirements to networks that include multi-tenancy and traffic isolation. In the next five years, we expect operators to pursue additional MVNO and M2M business models. Each of these business models relies on partnerships with external service providers. To a lesser extent, we will also see partnerships between operators and OTT service providers although the business nature of these relationships is not yet entirely clear.

6.1 MobileVirtualNetworkOperators(MVNO)As the business models have matured, more and more MVNOs are taking greater control over their service offering by building their own core network and service network infrastructure and relying on the host operators only for spectrum and RAN.

The combination of virtualization and cloud services can potentially reduce the cost of becoming a more complete or full MVNO with its own core network and service network infrastructure. Host mobile operators (MVNEs) can support this approach by building a cloud/NFV-based mobile infrastructure, in the process expanding their market opportunity. We can envision this trend continuing with literally dozens if not hundreds of virtualized core, services and OSS plat-forms in the cloud to support full MVNOs.

Each full MVNO requires its own service infrastructure with unified service delivery and orches-tration environment. This requirement means that ADCs, or more specifically virtualized ADCs (vADCs), have a key role in enabling a cloud and NFV-based full MVNO model. Host operators enabling MVNOs require a scalable ADC platform that can support a large number of vADC instances to support an expanding set of MVNOs.

Multi-tenancy will be a major requirement to deliver a cloud-based MVNO solution since traffic isolation and routing must be performed for each MVNO. Moreover, Virtual Network Functions (VNFs) for a specific MVNO may be located in multiple data centers. Virtual ADC instances, each with a MVNO specific traffic policy configuration, can meet the multi-tenancy require-ments to support a large-scale full MVNO model.

A full MVNO may be connected to multiple host operators for increased radio capacity or for global coverage. Traffic aggregation and disaggregation is required between virtualized network instances and RANs from different host operators. Additionally, with vADCs as unified service delivery platforms in the service network, full MVNOs can leverage traffic steering and service chaining features for personalized services.

6.2 Machine-to-MachineMachine-to-Machine (M2M) services are expected to be the next big opportunity in the mobile industry. Dubbed as the Internet-of-Things (IoT), M2M is forecasted to bring billions of M2M connections online in the next ten years. Gartner predicts that by 2020 there will be more machines connected than people while Cisco’s Internet Business Services Group (IBSG) and other research organizations predict fifty billion connected devices by 2050. But even a fraction of these projections represents huge growth for mobile operators.

More MVNOs are taking greater

control over their service offering.

Host operators or cloud operators

enabling MVNOs require a

scalable ADC platform.




As M2M traffic ramps up, operators must be prepared for the next deluge of traffic from billions of connections. The signaling traffic generated from billions of M2M devices will require a high capacity and easily scalable control plane architecture. Since M2M service infrastructure must be scaled to meet user plane and control plane traffic, ADCs will play an important role in distrib-uting traffic throughout the M2M infrastructure.

The M2M service infrastructure consists of Connectivity Device Platforms (CDP) operating at the network layer and Application Enablement Platforms (AEPs) implementing service specific functions. M2M applications are built on top of AEPs.

The M2M service infrastructure is a natural fit for cloud-based service delivery. Operators and their M2M partners are building cloud infrastructure for deploying AEP server farms for different verticals. There are also M2M MVNOs who are building out vertical-specific cloud infrastructure hosted by operators or by other cloud operators.

The ADC, or more specifically vADC, deployments in the M2M cloud can enable operators and M2M MVNOs to deliver optimized M2M services (Figure 7). Specifically, as operators build AEP server for different verticals, multiple vADC instances can be deployed to implement vertical-specific traffic management policies.

While vADCs in their current form play a major role in M2M services, the implementation of M2M specific functions can greatly enhance the ADC’s value in M2M service delivery. For example, overloading is a big concern in M2M applications when millions of devices try to access the cloud platforms after an outage or due to misconfiguration or simply more devices. Since ADCs are in the traffic path they can implement effective overload controls as config-ured by policy management. Alternatively, ADCs integrated with cloud management stacks

Operators must be prepared for

the next deluge of traffic from

billions of M2M connections.

The M2M service infrastructure

is a natural fit for cloud-

based service delivery.

Figure 7. The M2M Cloud with ADCs

3G/4GNetworks

M2MCloud

3G/4GNetworks

AEP

AEP

AEP

AEP

AEP

AEP

AEP

AEP

AEP

CDP

vADC

Vertical 1

Vertical 2

MVNO

vADC

vADC

...

CDP: Connectivity Device Platform (L3 Functions)AEP: Application (Service) Enablement Platform (L4–L7)

ADC Value Addition (Overload Control, Service Chaining, Etc.)





can initiate service orchestration to spin up virtual AEP servers to increase capacity to handle increased traffic.

Multi-tenancy is another important requirement for M2M services. Apart from deploying their own M2M clouds, operators can also enable clouds for M2M MVNOs running on the mobile operator’s network. Virtualized ADC platforms with multiple ADC instances can be enabled for the operators to implement multi-tenancy to support M2M clouds from different MVNOs hosted on the operators’ networks. Each ADC instance is assigned to a different M2M cloud, thus enabling the M2M MVNOs to set their own traffic management policies.

The deployment of ADCs with service chaining capabilities can enable operators to offer addi-tional Value Added Services (VAS) for M2M clouds. Operators can offer a machine data analytics service to Small and Medium Businesses (SMB) running their M2M applications on the opera-tors’ M2M clouds. Given that ADCs are in the traffic path, it can automatically send traffic to a data collector for analysis. As another example, traffic can be routed through encryption servers to meet a regulatory framework for verticals such as healthcare.

6.3 OTTServiceProvidersMany mobile operators are partnering with OTT service providers to try to add value to the OTT services. Mobile operators can enhance the quality of OTT services by assuring QoS and adding Value Added Services to OTT traffic. When operators have deployed a unified service delivery platform with advanced Layer 4 through Layer 7 intelligence, they can identify and treat their partner’s OTT traffic differently from other types of traffic.

Furthermore, OTT services can benefit from customized service chains. For example, video traffic from a partner OTT service provider can be steered through video optimization servers for optimized delivery processing. Additionally, the service delivery platforms can provide content caching for the more frequently accessed content, thus relieving OTT servers and reducing latency for content delivery.

Multi-tenancy is another important

requirement for M2M services.




7.0 ConclusionsThe need to provide service personalization and support new business models will drive mobile network evolution. In particular, the mobile services network needs to move towards a unified services architecture leveraging virtualization and cloud based networking.

ADCs are a key enabler for virtualization and cloud services. ADCs can already bring virtualiza-tion and service orchestration capabilities to mobile services network, thus enabling personalized services. ADCs play a major role in the move to NFV and SDN models, such as by enabling application aware networking.

ADCs can scale the control plane architecture in LTE and IMS networks. Diameter is more than a control plane protocol since it is central for service delivery and key OSS processes, such as policy control and billing. The ADC’s pedigree in message-based load balancing allows it to act as a Diameter load balancer to scale Diameter infrastructures. ADCs also play an important role in the session control layer of VoLTE. SIP load balancing enables traffic management and optimized utilization of SBCs and Application Servers.

MVNOs and M2M services are key focus areas for operators. Virtualization and cloud archi-tecture represents the best way to handle large scale deployments of these services. ADCs with multi-tenancy support enable operators to integrate with a diverse set of MVNOs and M2M providers. As operators partner with OTT service providers, ADCs can serve as service delivery platforms for operators to manage the interaction.

ADCs are a key enabler for

virtualization and cloud services.


Documents

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