There are more than 85 Diameter interfaces defined by the 3GPP and related standard bodies. These interfaces cover a range of network functions and is heavily used in IMS. With all LTE mobile networks, there are even more interfaces and transactionsDiameter signaling relates to network attachment and service delivery Data services – Internet, video, etc.VoIP and IMS servicesNetwork attachmentLocation updatesRoamingDiameter signaling relates toAuthenticationAuthorizationLocation/mobility trackingCharging/credit checksQoS/bandwidth-based admission controlNew attachmentsResets: UE crashes, battery swaps, etc.Power on after a few hours: plane trips, turn off for the nightRegister to LTE network and IMSTracking updates: moving aroundVoice and data sessions (bearer creation and teardown)Web surfing, email, videoVoLTE, RCS (IMS)QoS and charging interfacesRoaming: data and VoLTEAuthentication to visited networkAuthorization of servicesCharging and QoS policies
Customers are embarking on IP migration in the core. They are doing it to reduce costs (vs TDM) and enable new services and business models. But they leave behind some key aspects of the PSTN that result in challenges in the IP realm. Plus TEMs push solutions that are overly complex or costly. The chief challenges they face in this migration areLimited scalability – the volume of messages and Diameter transactions for authentication, mobility updates and each voice or data session can be huge. The processing load on Diameter elements can impact the ability to scale individual elements as well as the network at large. Complex provisioning and routing – given the number of elements, where they are located and how they must interconnect, the programming of route tables and the effective routing of messages in a network can be daunting to provision, maintain and change as the network grows. This complexity is costly in two areas: it results in an opex nightmare and slows down growth.Service availability is impacted by overload and network failure – the servers involved in processing various authentication, QoS or charging functions are not equipped to deal with spikes in volume; this can impact quality or availability of services. Elements as well as network data centers can also be taken out of serv iceLack of visibility – the ability to collect and correlate all messages with the number of elements and vendors and volume of transactions is formidable if not impossible; the information from these messages is critical for network planning, troubleshooting and daily operations.Multi-vendor interoperability – while Diameter is a standard, there are numerous interpretations of that standard as IMS and LTE has evolved and as more vendors enter the market. There are also differences in networks, such as transport protocol or IP version, that can cause incompatibility and transaction failures. Multi-vendor environments are long known for interoperability problems that add extra time or costs to an initial deployment and ongoing operations. The lack of interoperability hinders freedom of choice for service providers.
I-DSC is like an I-SBC connecting disparate retail and wholesale service providers together. This includes roaming and federation with OTT/MVNO providers. A C-DSC like a SRP, routing and aggregating Diameter traffic internal to a single operator. Core DSC applications extend to:Charging – online and offline (OCS proxy)QoS – bandwidth reservation and modification (PCRF proxy)Subscriber authentication and authorization (HSS proxy)Mobility and location updates (AAA proxy)HSS – Home Subscriber ServerPCRF – Policy Charging Rules Function
Routing of Diameter messages: flexible routing policies allow messages to be accepted or rejected depending upon source, destination, message type, and message value, thereby allowing the application of business logicDiameter signaling normalization: AVPs, and grouped AVPs can be normalized similar to SIP HMR, through the use of regular expression matching. AVPs can be removed, inserted, and modified. In addition, transport layer interworking between SCTP and TCP is performed automatically between ingress and egress interfaces, as is IPv4 to IPv6 conversion.Comprehensive security: Load limiting controls, including load balancing, and message rate limiting are extremely important to protect vulnerable Diameter elements. In addition, DDoS controls can be applied in order to stop out-of-control Diameter elements, such as new MME software loads that may exhibit bad (i.e. massively high rates of signaling) traffic under corner conditions.Comprehensive management: allows isolation and troubleshooting of Diameter issues within the network
Again, Benefits to Acme Packet Sales teamsDrive SBC, DSC, SR salesFills product gap and levels competitive landscape
Scaling Diameter for LTE• Introduction• What is Diameter and Why it is important• What it means for operators and vendors• Market projections• Diameter signaling controller requirements• Role of Centralized Routing Databases
What is Diameter?• Next generation signaling protocol, replacing SS7• Exchange subscriber profile data between fundamental core network elements/systems: – IMS – EPC – Billing systems – Roaming exchanges
Why is Signaling & Diameter Important?• Since LTE has a relatively flat architecture, the core network is more exposed to signaling, than with 3G, which has an RNC.• Network outages and/or poor performance – Increases churn – Destroys brands
Diameter Signaling Controllers• New product category, encompassing DEA, DRA, protocol translation, other functions.• More efficient, scalable, and reliable Diameter networks• Many dimensions for growth: – Subscribers – Voice and Data usage/sessions – Dynamic billing and policy applications – Roaming
Diameter Signaling Controllers• Multi-billion dollar market opportunity – New product category – Major technology transition – Continued strong organic growth in signaling• High degree of vendor activity – Very early days; Accelerating RFI/RFP activity – Much more entry and consolidation to come
DiametersignalingcontrollerrequirementsOct 2012 Kevin Mitchell @mitchellkp firstname.lastname@example.org
Scaling DSCs with CentralizedRouting Databases Simplifies provisioning – eliminates silos PSTN Wholesale/ IPX MNO Highly scalable: 100s-1000s STP Diameter of millions of entries servers Routing DB Support for dynamic, complex routing Registries decisions LCR LNP OSS Diameter clients xCSCF Integration with legacy Fixed Mobile routing databases DB query Diameter Extensible – SIP, multi- vendor, future applications SIP SOAP/XMLOct. 2012 Acme Packet | www.acmepacket.com
Role of CRDB in NGN Centralized Routing and Database Services
Common Data – Multiple Applications• SIP Services, DIAMETER services, TDM services – All need access to shared/common routing data• Common Routing Data – Subscriber data – Portability-data – Code-range data – MVNO data (Virgin Mobile) – OTT data (GoogleVoice) – Carrier-ENUM data (IMS endpoints) – Routing policy data (Route-list for destinations) • Internal routing • Trusted interconnect partner routing • Least cost interconnect routing
Common Data – Multiple Applications Portability Data Code-Range Data Subscriber Assignment Data Carrier-ENUM Interconnect Trunk-Group Profiles MVNO destinations OTT destinations (Google Voice)MULTIPLE Geographic destinations (LCR) MULTIPLE DATA Local Routing Policy DATASOURCES L SOURCES We ocal ery AP b, p qu P, IN File rovis ral , S ion fer , MA OA ing P/X Re AIN ML M, E NU CRDB (ENUM, SIP, INAP, MAP, CAP, WIN, DIAMETER) STP DRA S-CSCF Connection Management Services C4/C5 MSC SMS/MMS MGCF DEA pCSCF AS/TAS SBC Network Edge Services CONVERGED TDM & IMS NETWORK
Key Issues To Consider• In-Switch Routing Model is Costly – Provision common data into every switch – Learn routing database model for every switch – Staff routing experts for every switch – Fix routing inconsistencies across multiple platforms• CRDB Model is a Strategic Decision – We’ve been living with cost of in-switch routing model for past 100-years. Obviously we can continue. – Switching to a centralized model requires some strategy vision to avoid the costs of the old model. – Introduction of IMS-Core and DIAMETER services are opportunity to switch to a centralized model • Reduced network complexity (lower operating costs) • Faster service deployment (faster revenue generation) • Enhanced routing options (improved quality)
Additional Resources Blog Post: The Next Generation Signaling Core for LTE and IMS White Paper: Scaling Diameter in LTE and IMSOct. 2012 Acme Packet | www.acmepacket.com
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