Diameter Interworking Interworking Eases Network Transition, Ensures Widest Range of Roaming and Increases Roaming Revenues
Table of Contents Introduction..................................... 3 Business Challenges / Drivers........................... 3 Diameter to Diameter Interworking........................ 3 Diameter to SS7 Interworking........................... 5 Scenario 1.............................................. 5 Scenario 2.............................................. 6 Scenario 3.............................................. 6 Scenario 4.............................................. 6 Conclusion...................................... 7 What to Look for in an Interworking Solution................... 7 Consistent Routing Engine.................................... 7 Routing Segmentation....................................... 7 SDN and NFV............................................ 7 Experience in Telecommunications Signaling SS7 and Diameter............... 7 Specializing in Network Signaling & Routing.......................... 7 Sonus DSC 8000 Advantage............................ 8 Sonus DSC 8000 Distributed Routing Engine......................... 8 Sonus DSC 8000 Virtual Instances.............................. 8 Sonus DSC SWe (Software edition)................................ 8 Sonus Long History in Telecom Signaling............................ 8 Specializing in Telecommunications Signaling and Routing Solutions............ 8 About Sonus..................................... 9 2
Introduction All of the mobile market analyst data points lead to two interesting facts. First, Long-Term Evolution (LTE) is the fastest developing mobile system technology in history, and second, SS7-based networks including 2G, 2.5G and 3G will be around for quite some time. How can both of these facts be true simultaneously? The Global mobile Suppliers Association s (GSA) Evolution to LTE Report, issued in January 2015, cites that there are currently 360 commercially available LTE networks in 124 countries. The facts are irrefutable; LTE is growing rapidly. Intelligence reports from GSMA an association representing mobile operators interests worldwide state that there are currently 3.6 billion unique mobile subscribers and a total of 7.3 billion mobile connections. In addition, Informa Telecoms and Media reported that as of September 2014 there were 373 million LTE subscribers. These market research numbers indicate that currently LTE subscriptions account for approximately 10% of the total mobile market, so 90% of all mobile subscriptions are served by SS7 networks (2G, 2.5G, and 3G). Future LTE market projections by Juniper Research indicate that by 2019 there will be approximately 1.8 billion LTE connections, meaning that 22% of the total mobile market will be LTE. Conversely, legacy SS7 networks, including 2G, 2.5G and 3G, will serve 78% of the mobile market or 6.4 billion connections. These market numbers highlight the need to address the hybrid or multi-protocol environment of mobile telecommunication signaling for the foreseeable future. Business Challenges and Drivers Juniper Research s findings indicate that by 2018 mobile data roaming revenues will reach $42 billion and will account for 47% of all roaming revenues. These market research numbers, coupled with LTE mobile subscription research, highlight two important factors: Even in the face of regulations restricting roaming charges, roaming is becoming an ever-increasing portion of revenues for service providers, especially mobile data roaming. Service providers ability to achieve and maintain these roaming revenues are contingent upon providing subscribers the Quality of Service (QoS) and Quality of Experience (QoE) expected to ensure brand loyalty and the lowest possible churn rate. In order for mobile service providers to realize their share of the rapidly increasing 4G LTE/Evolved Packet Core (EPC)/Diameter based mobile revenue, the following challenges need to be addressed: 1. Diameter-to-Diameter interworking at both the core and edges of the LTE/EPC Diameter based networks 2. Diameter-to-SS7 MAP interworking Addressing these issues will ensure that operators roaming revenues will be optimized by providing subscribers with the best QoS, and thus reduce subscriber churn due to bad roaming experiences. Diameter to Diameter Interworking When reading the Diameter specifications or other related Diameter information, Diameter interworking is typically defined in terms such as: 1. Diameter to RADIUS interworking 2. Diameter to SS7 MAP interworking While both of these are important, they are only pieces of the Diameter interworking puzzle. Any discussion about Diameter interworking should also include Diameter-to-Diameter interworking. Increases in the deployments of LTE/EPC/Diameter based networks, coupled with the increases in LTE roaming agreements, are driving the need for interconnection between both service providers and multiple vendors equipment. 3
In today s environment, vendors may interpret the Diameter specifications differently, yielding Diameter implementations that are incompatible with each other. Also, Diameter vendors equipment may be using a different software release or supporting a different 3GPP specification release, which could cause protocol inconsistencies. These problems can occur anywhere in the network but are exacerbated at the network edge, where multiple networks converge. Service providers have little knowledge of the equipment and its software version in the foreign interconnected network. Given these issues, a Diameter routing device placed at either the edge or core of the network is the perfect place for the protocol mitigation to take place. While this has been addressed by the GSMA in IR.88 with definition of the Diameter Edge Agent (DEA), IR.88 states that interconnected networks should view the DEA as a relay agent. When the device is defined as a relay agent, the device does not have the authority to modify any portion of the Diameter Message outside of routing information; message modification outside the routing context is the responsibility of a Diameter Proxy Agent. To keep terminology and implementations consistent, the answer might be to route the conflicting messages off to a Diameter Proxy Agent (maybe in the same physical device) that advertises support for the application in question. The Diameter Proxy Agent would then perform the AVP/message manipulation required. After the protocol inconsistency mitigations take place, the message would be routed as originally required. Subsequent answer messages would have to be routed back to this proxy agent for translations back to the original format prior to being sent to the interconnected network. Even if the interconnected devices in both networks are from the same vendor, there is no guarantee that they are of the same revision or same software version; therefore the protocol differences can still occur. Importance of understanding Diameter-to-Diameter interworking cannot be overstated! With the growth in LTE/EPC/Diameter based networks and the increase in roaming agreements between network operators, the importance of Diameter-to-Diameter interworking cannot be overstated. The recommended solutions listed in this paper provide a valuable tool to solve the dilemma of Diameter-to-Diameter interworking without having to incur either the cost or delay of trying to resolve the issues through network equipment vendor channels. 4
Diameter to SS7 Interworking Understandably, the 3GPP selected the Diameter Protocol as the TCAP replacement to perform AAA functions and overcome some of the deficiencies of RADIUS in the LTE/EPC networks. When implementing new network architectures and protocols, the following question always arises: How are we going to provide access to legacy equipment and services, given that we can t migrate the entire network and existing subscribers to the new technology overnight? On the surface the answer is quite simple: Provide an interworking capability between the old and new technologies and vice versa. The daunting task is actually implementing these capabilities and choosing the specific applications that interworking will support. Diameter to SS7 MAP Interworking As stated earlier, Juniper Research projects that by 2019 22% of mobile connections will be LTE and the remaining 78% will be served by SS7-based networks (2G, 2.5G & 3G). Given these numbers, it is important to allow LTE/EPC/Diameter subscribers and 2.5G and 3G SS7-based subscribers to roam into networks regardless of the core technologies. This enhanced QoE for subscribers can be accomplished by providing a Diameter/SS7 MAP interworking function, typically located in the LTE/EPC/Diameter network. The Diameter to MAP interworking capability is specified by 3GPP TS 29.305 v12.1.0 (2013-12). TS 29.305 describes four scenarios for interworking: Scenario One: S6a/S6d Pre Rel8 Gr interworking scenario with one IWF Scenario Two: S6a/S6d Rel8 Gr interworking scenario with one IWF Scenario Three: S6a/S6d S6a/S6d interworking scenario with two IWFs Scenario Four: S13/S13' Gf interworking scenario with one IWF Scenario 1 This scenario covers the case in which subscribers from an SS7/MAP-based network roam into a LTE/EPC/Diameter based network. The assumption in this scenario is that the HLR in the legacy network is 3GPP Pre-Release 8. The interworking function provides a protocol conversion between either the MME S6a Diameter interface and the HLR SS7 Gr interface or the SGSN Diameter S6d interface and the HLR SS7 Gr interface. This capability can be used in two cases: 1. Between operators when the home network is a legacy SS7-based network and the subscriber is roaming into an LTE/EPC/Diameter based network. 2. Within a single service provider s network when the network consists of both SS7 and Diameter segments. 5
Scenario 2 This scenario covers the case where a subscriber from a home UMTS or GPRS (3GPP pre-release 8) network roams into an LTE/EPC/Diameter based network. The interworking function provides a protocol conversion between either the MME S6a Diameter interface and the HLR SS7 Gr interface or the SGSN Diameter S6d interface and the HLR SS7 Gr interface. Scenario 3 This scenario describes a case in which two companies have an in-place roaming agreement based on SS7 and they wish to continue the use of this agreement. This case assumes that both networks are LTE/EPC/Diameter based networks and the transport of information between the networks is based on the SS7/ MAP Gr interface. Scenario 4 Scenario 4 defines a case in which a 3GPP Pre-Release 8 UMTS/GPRS user roams into an LTE/EPC/Diameter network and the validity of handset is to be checked in the home network s Equipment Identity Register (EIR). This scenario defines two mapping cases: 1. Between the MME S13 Diameter interface and the EIR Pre-Release 8 SS7 Gf interface. 2. Between the SGSN S13 Diameter interface and the EIR Pre-Release 8 SS7 Gf interface. DS-1401 12/23 6
Importance of Understanding Diameter-to-SS7 Interworking scenarios In today s evolving network, it is important to understand both the legacy SS7 network and the LTE/EPC/Diameter network, as well as the interactions between these two networks. This understanding will allow the most effective network designs to meet the needs of mobile subscribers. Conclusion Today s network operators can be characterized by their desires to: Stop the tide of declining Annual Revenues Per User (ARPU) Increase roaming revenues Have a flexible, robust QoS framework Provide the subscribers with an enhanced QoE In order to address these desires, service providers must provide the widest reach of stable services with the highest quality, and most efficient, network possible. A key component in providing these capabilities is the Diameter interworking function, including: Diameter to Diameter interworking Diameter to SS7 Map interworking What to Look for in an Interworking Solution Consistent Routing Engine Another important architectural issue to be considered in the selection of a Diameter Signaling Controller (DSC) with Diameter Edge Agent (DEA) capabilities is whether or not the internal software design is based on universal protocol switching and routing concepts. Routing Segmentation The DEA should include the ability to segment the routing rules on a per interconnected network basis. This segmentation would provide the ability to administer routing rules, shape traffic, implement Diameter to Diameter protocol mediation, and provide Diameter to SS7 interworking on a roaming partner or interconnected network basis. This capability allows increased control, reduces administrative risks, and provides the flexibility required in network design. Network Functions Virtualization (NFV) The DEA should include the ability to be deployed virtually [i.e., Network Functions Virtualization (NFV)] or as an appliance to meet network operators desire to reduce costs and use new hypervisor and orchestration technologies. Experience in Telecommunications, Signaling SS7 and Diameter In order to provide solutions that span the evolutionary stages of telecommunications signaling (SS7 to Diameter), it is imperative that the solutions vendor has experience in the concepts of both SS7 and Diameter signaling. The experience in the legacy SS7 protocol and its associated network provides the STP/DSC vendor with the unique knowledge of issues and concerns that occurred within legacy networks. This knowledge allows the vendor to provide solutions that mitigate these issues in new networks and protocols such as LTE/EPC/Diameter. Specializing on Network Signaling & Routing There will always be differences in the implementation and interpretation of specifications when any network or protocol is deployed. These differences can cause catastrophic problems within networks and across the boundaries between different networks. A network equipment vendor specializing in protocols and routing can provide mediation capabilities that solve the protocol inconsistencies and thus eliminate their network impact. 7
Sonus DSC 8000 Advantage Sonus DSC 8000 Distributed Routing Engine The internal design of the DSC 8000 utilizes Sonus advanced Distributed Routing Engine. The DRE concept provides instances of the DRE on each routing processor and intercommunications between these instances, providing reliability and scalability of routing across the entire platform. An additional advantage for the DRE is its registration capabilities supporting both SS7 and Diameter. Sonus DSC 8000 Virtual Instances The DSC 8000 enables the definition of separate DEAs within a single DSC 8000 platform. Each of these virtual DEAs has its own separate routing and screening rules that include the ability to shape traffic on a per-peer basis. This shaping includes traffic flow control, throttling and congestion per-peer. Architected for extensibility and straightforward evolution to future Diameter applications, this high-powered platform makes the DSC 8000 ideal for LTE/EPC and IMS networks. Sonus DSC SWe (Software edition) The DSC SWe delivers the same advanced features and functionality of Sonus hardware-based Diameter Signaling Controller (DSC) in a virtualized platform, providing greater deployment flexibility for network operators. NFV plays an increasingly critical role in today s next-generation and Cloud networks. Building upon its strategy to virtualize the field-proven code base of its industryleading hardware platforms, Sonus separated its Diameter software from the DSC 8000 hardware and architected it to operate on industry standard commercial off-the-shelf (COTS) servers. For customers looking to leverage new and existing platforms to support NFV functionality, the DSC SWe allows customers to deploy a fully featured DSC co-resident with other applications. Sonus Long History in telecom signaling Sonus is uniquely positioned to provide independent signaling and routing solutions to the telecommunications industry. Sonus extended history in delivering Session Initiation Protocol (SIP) solutions, coupled with its acquisition of Performance Technologies, enables Sonus to expand and diversify its portfolio to both SS7 and Diameter products/solutions. This vast experience in all aspects of telecommunications signaling SS7 to SIP to Diameter enables Sonus to deliver solutions over the broad spectrum of telecommunications signaling, resulting in more efficient, scalable, secure and cost-effective networks. Specializing in Telecommunications Signaling and Routing Solutions Sonus focus on signaling and routing solutions, combined with its expertise in SS7, SIP and Diameter protocols, provides the objectivity required to deliver the most efficient SS7, SIP and Diameter interworking capabilities in the industry. These interworking functions ensure that multi-vendor networks perform at their peak, and remove the need to constantly upgrade network elements due to protocol inconsistencies. 8
About Sonus Networks Sonus enables and secures real-time communications so the world s leading service providers and enterprises can embrace the next generation of SIP and 4G/LTE solutions including VoIP, video, instant messaging and online collaboration. With customers in more than 50 countries and nearly two decades of experience, Sonus offers a complete portfolio of hardware-based and virtualized Session Border Controllers (SBCs), Diameter Signaling Controllers (DSCs), policy/routing servers and media and signaling gateways. For more information, visit www.sonus.net or call 1-855-GO-SONUS. Sonus is a registered trademark of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated. Sonus Networks North American Headquarters Sonus Networks APAC Headquarters Sonus Networks Limited EMEA Headquarters Sonus Networks CALA Headquarters 4 Technology Park Drive Westford, MA 01886 U.S.A. Tel: +1-855-GO-SONUS 1 Fullerton Road #02-01 One Fullerton Singapore 049213 Singapore Tel: +65-68325589 Edison House Edison Road Dorcan, Swindon Wiltshire SN3 5JX Tel: +44-14-0378-8114 Homero No. 1933-902 Col. Los Morales, C.P. 11510 Mexico City, Mexico Distrito Federal Mexico Tel: +52-55-1950-3036 Int l Tel: +1-978-614-8741 To learn more, call Sonus at 855-GO-SONUS or visit us online at www.sonus.net The content in this document is for informational purposes only and is subject to change by Sonus Networks without notice. While reasonable efforts have been made in the preparation of this publication to assure its accuracy, Sonus Networks assumes no liability resulting from technical or editorial errors or omissions, or for any damages resulting from the use of this information. Unless specifically included in a written agreement with Sonus Networks, Sonus Networks has no obligation to develop or deliver any future release or upgrade, or any feature, enhancement or function. Copyright 2015 Sonus Networks, Inc. All rights reserved. Sonus is a registered trademark of Sonus Networks, Inc. All other trademarks, service marks, registered trademarks or registered service marks may be the property of their respective owners. DS-1501 6/2 9