Network Evolution - Migration Strategies for Success-FINAL

8/2/2019 Network Evolution - Migration Strategies for Success-FINAL

http://slidepdf.com/reader/full/network-evolution-migration-strategies-for-success-final 1/25

NETWORK

EVOLUTION:

Migrat ion Strategies for

Success

This paper, jointly prepared by Fr& Sullivan and Tekelec, provides

overview of industry trends andissues impacting the evolution owireless and wireline networks and proposes signaling related

solutions that span the TDM, NGand IMS domains.

“Partnering with clients to create innovative growth strategies”



TABLE OF CONTENTS

Introduction 3

The Promise of IMS 4

Current State of the Market: Operators’ Perspective 5

Service Providers and the IMS Business Case 5

Carriers Evaluating Transitional Strategies 6

Network Migration: Key Technical Challenges 7

Implementing a SIP Signaling Layer in the NGN 7

Tekelec’s NGN SIP Signaling and Session Management Solution 10

Limitations of Today’s Network and Bridging the Gap to Future Networks 10

Limitations of Today’s Intelligent Network 10

The Hybrid Network has Gaps Between the IN and IP Serv ices Architec tures 11

Service Mediation in Intelligent Networks 12

Servi ce Orchest ra tion w ith Med ia tion across IN and NGN and IMS Networks 13

Tekelec’s SCIM Solution 14

Gradually Deploying an IMS Architecture 14

Tekelec IMS Solution: Open IMS Alliance 15

Ensuring All SIP Issues Are Addressed 17

Bandwidth Inefficiency of SIP in a Wireless Environment 19

The Search for the Best Transitional Strategy 21

Summary and Concluding Remarks 22

TABLE OF

CONTENTS

Frost & Sullivan

2



INTRODUCTION

Given the current environment, how should carriers consider evolving their

networks in order to support SIP, VoIP and multimedia services?

The communications landscape is dynamic and intensely competitive. Deregulation,

mergers and acquisitions, rapidly evolving technology, and changing customer behavior

profoundly impact network architects and decision-makers. Operators must carefully

consider a number of market drivers as they evolve their networks and explore the

potential path of deploying IMS at the control layer. These market trends and network

changes are having a significant impact on the signaling network.

The migration to the IMS (IP Multimedia Subsystem) architecture has thus far proven to

be an evolutionary rather than a revolutionary transition, and it will have an even larger

impact on the signaling layer. As the network evolves, the signaling protocol wil l migrate

from signaling system 7 (SS7) to session initial protocol (SIP) and the signal transfer point(STP) of the public switched telephone network (PSTN) will transition to the call session

control function (CSCF) of the IMS architecture.

Developing a sound understanding of IMS will help to establish the rationale that will

guide various decisions in architecting network evolution. Nearly immeasurable

investments of time and finances have already been made to develop the IMS standards

and supplementary technologies over the last two decades. Fundamental aspects of

efficient design have been guiding principles to ensure the maximum benefit to the

subscriber while preserving the ability of the service providers and application developers

to obtain a successful ROI. Insight into the impetus for IMS can be a guide for

determining how to prioritize network transitions.

The prevailing consensus in the telecom world is that the evolution to IMS will span many

years. In the interim, there will be a mix of signaling technologies deployed. While there

will be a gradual build-out oriented towards SIP based signaling, SS7 is expected to

remain an important signaling technology for years to come due to several factors such as

its importance in enabling roaming in a mobile environment and the large installed base of

SS7 technology.

Because the network is in a state of perpetual transition, the outcome can be considered

indeterminate at the point that migration begins . Ultimately, given any path to IMS, there

are several choices operators can make to leverage their existing investment andmaximize the probability of success given the dynamic changes in technology. The ideal

architecture for the transition is one that provides flexibility to service providers by

enabling them to deploy new services on IP based technologies, while leveraging existing

services and infrastructure as long as it makes sense.

Operators must begin to focus on the steps that will enable a smooth transition. Tekelec

presents a multi-pronged strategy for assisting carriers to migrate to the next-generation

service delivery model (whether IMS or some other variant) at their own pace.

Frost & Sullivan

3



THE PROMISE OF IMS

IMS is a framework that allows the rapid development and deployment of enhanced,

revenue-generating multimedia services for fixed, mobile and cable operators. IMS offersa new modular approach towards call control and service delivery. This modular

architecture is achieved by separating the bearer traffic (in the transport layer) from the

signaling traffic (in the control layer). By disaggregating the transport, control, and

application layers, IMS promises to allow carriers to quickly and cost-effectively launch a

wide array of new multimedia services on their networks. This approach also enables

operators to seamlessly run a plethora of next-generation converged services over their

fixed, mobile and cable networks, achieve a faster time-to-market for new services and

have fewer performance bottlenecks.

The access agnostic nature of the specification makes it one of the most ambitious and

comprehensive standardization efforts to date, specifically addressing the evolution to

next-generation telecom infrastructures. IMS utilizes packet technologies for underlying

transport and relies upon SIP for call signaling between the various components.

The promise of IMS is the notion of re-utilizing common functions (such as billing and

presence) and then integrating them in a horizontal fashion . These functions can be re-

used for many different applications, as illustrated in Figure 1. This approach, called

functional decomposition, is far superior to the traditional vertical integration model, in

which common functions are replicated for each application.

Figure 1: IMS: A More Eff icient Service Implementation

Source: Frost & Sullivan

Frost & Sullivan

4

PSTN

“Stovepipe” Service Model IMS Service Approach

WLANRAN

IP Multimedia Subsystem

. . .

Application Servers

Network Subsystem

Base Station Subsystem

ControlLayer

ApplicationLayer

Transport

Layer

AccessLayer

......

......

Multi-service IP Network

P u s h t o T a l k

S e r v i c e

Q o S

B i l l i n g / O S S

P r e s e n c e

. . . . . . . .

I n t e r a c t i v e

G a m i n g

S e r v i c e

Q o S


P r e s e n c e

. . . . . . . .

V i d e o

S t r e a m i n g

S e r v i c e

Q o S


P r e s e n c e

. . . . . . . .

Billing / OSS

QoS

Presence

Session Management

and control

Common functions are replicated Common functions are reutilized



CURRENT STATE OF THE MARKET: OPERATORS’ PERSPECTIVE

Service Providers and the IMS Business Case

In a recent Frost & Sullivan carrier survey1 over 33 percent of carriers indicated their

belief that the IMS business case remains somewhat elusive. In fact, this was the most

often mentioned IMS caveat on that survey, as shown in Figure 2. The operator busines s

models will become more refined as carriers develop plans to offer new multimedia

services; however, there is still uncertainty about which applications will have the most

success.

Figure 2: IMS Caveats (According to a February 2007 Global Frost & Sullivan

Carrier Survey)

Source: Frost & Sullivan

Two groups have emerged: the early adopters, who are more willing to embrace IMS

today, and a skeptical group focused on immedia te and pragmatic issues. The early

adopters take a strategic approach and are less concerned with specific IMS applications.

At the other end of the spectrum are the service providers who take more of an

application prove-in approach. This group of carriers might typically remain sidelined and

choose to wait until further issues such as handsets, bandwidth and QoS are resolved, or

new IMS applications are created. These operators are concerned with the first five

applications to be deployed within the new IMS framework. For these operators it’s all

about the short-term business case for the applications rather than the long-term benefit

of the IMS framework. The focus is on a shorter payback period (typically a 6-12 month

horizon as opposed to 3 years).

Frost & Sullivan

5

1. Please refer to “IMS – Ready for Prime Time?” by Ronald Gruia, released by Frost &Sullivan in February 2007.

IMS Caveats

33%

25%

13%

9%

8%

4%4%

2%2%

Operators Still Adjusting to the IMS BusinessCase

IMS is Still a Work in Progress in the Standards Arena

IMS Not as "Open" as Advertised

More Interoperability Effort Is Required

IMS Security Still Perceived as a Risk

Carriers Need to Tackle Other Technical IssuesPrior to Embracing IMS

More IMS Handsets and Clients Needed forSuccess

Cost and Complexity of the Systems Integration

No "Killer Apps" as of yet to Justify theCommitment to IMS



There are multiple options to transition networks to maximize existing architecture and

eventually realize the benefits of IMS. Each of them entails several steps. These

incremental steps include migration of the control layer of SS7 to IP – this includes

deploying SIGTRAN (SS7 over IP) and/or eventually deploying an independent SIPsignaling control plane in the NGN. Another step would be linking the application layer

to the control layer by implementing SCIM (Service Capability Interaction Manager)

functionality to help bridge the transition from TDM to NGN, and eventually IMS.

Carriers Evaluating Transitional Strategies

Carriers are dealing with issues such as seamless service delivery across a variety of

network types as shown in Figure 3. While this happens, SIP and SS7 will continue to

coexist in carrier’s networks. In addition, operators will start capping their investments

in current technologies and gradually begin to shift them to new equipment purchases.

Figure 3: Co-existence of Signaling Technologies

Source: Tekelec

Carriers need to be able to provide new services to all subscribers in order to maximize

their ROI. The key takeaway is that a carefully planned transition strateg y is imperative to

make the NGN transition a technological, service and business success.

Frost & Sullivan

6

SS7 – 2G

SIGTRAN – 3G R4

SIP/SS7 Concurrence

IMStime



Network Migration: Key Technical Challenges

Since the IMS transition will be gradual, our discussions with various service providers

revealed that there will be a number of technical issues that require more immediateresolution as their networks evolve. These include the following:

• Implementing a SIP signaling and session control layer in the NGN: how can

operators architect a core signaling and session control layer ensuring that it is

scalable and that it can form the basis for an eventual migration to IMS?

• Limitations of today’s network and bridging the gap to future pre-IMS and IMS

networks: how can operators deliver seamless services in a hybrid network and

support service mediation and interaction between legacy, mobile, VoIP and IMS

networks?

•Deploying an IMS architecture gradually: once the transitional issues have beentaken care of (i.e., older “stovepipe” services can be delivered alongside newer

IMS applications and the signaling and session control layer has been

implemented), how can operators build out the final pieces of their IMS

network?

• Ensuring all SIP issues (present and future) are addressed: after the rollout of

the IMS network, some issues associated with the usage of SIP begin to emerge,

including overload conditions at the control plane, SIP signaling bandwidth

inefficiencies and failure recovery mechanisms. How should operators deal with

these SIP issues as their future networks grow?

The following sections discuss these challenges in some detail.

IMPLEMENTING A SIP SIGNALING LAYER IN THE NGN

A major issue with the NGN architecture is the lack of core-signaling infrastructure to

assist NGN elements with signaling and session routing activities. Without a hierarchal

session control layer, each NGN network element must handle all control layer related

tasks such as routing, traffic management, redundancy and service implementation. All of

this causes a number of barriers to creating an efficient network. For instance, each

NGN network element must make application layer routing decisions based upon the

destination address (i.e ., SIP URI). Thus, all possible routes must be defined at eachnetwork element so that each will have one or more signaling routes between them.

Hence, the combination of possible routes at the edge network results in the formation

of a logical mesh-network routing architecture2 as depicted in the following diagram:

Frost & Sullivan

7

2. This architecture exists at the application layer, riding on top of a layer 3 IP packetrouting network.



Figure 4: Hidden layer 5 mesh routing architecture

Source: Tekelec

This mesh architecture entails several critical challenges including:

• A host of scalability-related issues, for example routing table exhaustion,

provisioning and billing errors;

• Traffic flow controls, network failure recovery and other traffic management-

related issues;

• Interoperability tests must be performed between all possible signaling device

connections to ensure proper communication between the elements; and

• Difficulties implementing a consistent number portability scheme across the

entire NGN network.

Moreover, the current NGN architecture also contains the following architectural

deficiencies:

• Vendor dependencies: Without core session management, an NGN element

performs all application layer processing. Consequently, the behavior of

communication services (i.e., user interaction, features and more) is dictated by

how the vendor of the network element implements the service. Furthermore ,

implementing independent services offered by third party SIP application servers

becomes quite difficult. Hence, an operator may be locked into a single vendor

due to vendor specific service implementation in order to maintain service

consistencies across the network.

Frost & Sullivan

8

IP Packet Network

SIP

PBX

PBX

IAD VoIPEnd-Point

SIP

Services SBC

SBC

VoIP

VoIP

VoIP

Edge

Proxy

Edge

Proxy

RAN MG

A/Abis

RAN MG

A/Abis

MSC

Server

A “hidden” L5 logical mesh

routing architecture exists

on top of an IP packetrouting network.



• NGN lacks the IMS services framework: An important IMS architecture attribute

is the Home Service Control (HSC) framework. The HSC framework supports

delivery of multimedia services to both “Home” as well as roaming subscribers,

regardless of access method. The HSC framework allows an operator to offeradvanced multimedia services utilizing multiple clients (i.e., IP phones, soft-client

running on a PC or a wireless client running on smart wireless terminals) . The

core session management layer contributes directly to the HSC. Because the

NGN network architecture relies on the outmoded softswitch architecture for

managing sessions, the current NGN network is intrinsically voice-centric as

well as access dependent. Even though the NGN architecture utilizes the latest

IP technologies, it still follows the TDM voice service model and does not

leverage IP capabilities.

The core signaling and session control layer has proven its importance in the SS7 signaling

network and is identified in the IMS network architecture. The current NGN architecture

does not have a core SIP signaling and session control layer. Therefore, it cannot be

properly expanded without the implementation of a suitable signaling and session control

framework capable of off-loading various SIP signaling and session tasks from the edge

NGN elements. With a capable session layer, session-related tasks are migrated from the

edge NGN nodes to a centralized core SIP session framework. The resulting

architecture, depicted in Figure 5, allows the NGN network to grow systematically in

response to increasing demand for VoIP, while avoiding the various limitations previously

mentioned.

Figure 5: NGN with core SIP signaling & session framework

Source: Tekelec

Frost & Sullivan

9

IP Packet Network

SIPPBX

PBX

IAD VoIPEnd-Point

SIP

Services SBC

SBC

VoIP

VoIP

VoIP

Edge

Proxy

EdgeProxy

RAN MG

A/Abis

RAN MG

A/Abis

MSCServer

Tekelec is proposing a L5

control framework to provide

SIP routing & control

L5 Controls



This session-based framework also presents an ideal opportunity to introduce the

benefits of an IMS architecture into the NGN environment. Essentially, the IMS session

management technology is a perfect candidate for implementing a signaling layer in the

NGN. With the appropriate signaling and session control framework the NGN network can realize many of the attributes promised by the IMS architecture, such as access

independence, Home Service Control model, subscription-based service orchestration,

and multimedia support.

Moreover, with an independent control layer, a robust and bearer independent signaling

and session control network can be implemented to offer highly available signaling that

provides session setup for any type of multimedia serv ice. Therefore, an operator can

offer not only VoIP but any other type of media with the reliability and scalability of an

SS7 network.

Tekelec’s NGN SIP Signaling and Session Management Solution

Tekelec’s acumen and market leadership in SS7 signaling go a long way in providing

credibility to the company’s belief in the importance of a media independent session

control layer, and in bringing IMS CSCF technology to the NGN community.

Nonetheless, the 3GPP IMS CSCF cannot simply be deployed within the NGN without

adapting its protocols and procedures. Hence, Tekelec offers a unique session

management solution for the NGN environment that adheres to 3GPP IMS CSCF

definitions , but is also adaptable to the changing environment of the NGN. Called the

TekCore Session Manager, it provides SIP signaling router (SSR) functionality for the NGN

and supports 3GPP-defined IMS session control functionality to handle various session

management and control tasks needed within the NGN.

TekCore is compliant with the 3GPP IMS S/I-CSCF specifications, while offering

adaptations for interworking with non-3GPP compliant IP environments. TekCore’s SIP

signaling router (SSR) function introduces a session control framework, plus the latest in

IMS technology to the NGN. IMS compatibility provides seamless interworking and

facilitates the evolution to an IMS architecture in the future.

LIMITATIONS OF TODAY’S NETWORK AND BRIDGING THE GAP TO

FUTURE NETWORKS

Limitations of Today’s Intelligent Network

The package of services that can be offered to any single subscriber are limited in today’s

network. To trigger servi ces in the network, the subscriber ac tivates them through the

access network of the service provider. When the subscriber acti vates a call, a single

trigger is generated that can be used to initiate applications in the network which likely

reside on an SCP. With only a single tri gger, the service provider can only offer the

Frost & Sullivan

10



servi ces available on the “triggered” SCP. While some SCP vendors offer more appealing

service portfolios than others, there are typical disadvantages associated with vendor

lock-in.

Another challenge to easily selecting among application vendors is the variety of flavors

of SCP access technologies including BICC, INAP and CAMEL variations. Access

networks are only capable of interacting with a single interface without protocol

conversion. Each application essentially becomes an isolated service delivery solution

within the network. This delivery approach, called a “siloed” architec ture, prevents the

service provider from easily maximizing services for their subscriber populations.

However, one of the most significant limitations in the IN application layer is that the

ideal group of services for a subscriber group are generally not on the same platform and

cannot be offered to subscribers as part of a portfolio. Each time a new technology or

service is introduced at the access level, existing applications must be modified and re-

connected, creating operational and maintenance issues as well as bottlenecking the

introduction of new services.

To execute more than one IN application requires service orchestration. Service

orchestration enables a subscriber to access more than one application and it determines

the order and precedence of the services. Service mediation provides protocol inter-

working when a service application client and an application server employ different

protocol technologies. The end result without service orchestration and mediation is an

inflexible architecture that creates CAPEX, scalability and interoperability challenges for

the operator with limited opportunities to extend ARPU.

The Hybrid Network has Gaps Between the IN and IP Services Architectures

Operators that deploy NGN networks on any scale with existing networks face

challenges. Perhaps one of the most pre-eminent issues for operators that are gradually

transitioning a network is the importance of creating a seamless experience for

subscribers. This issue is critical because a change in basic and familiar services with the

subscriber could trigger a sudden turnover of the subscriber base . Therefore, network

providers want to ensure that existing applications can be delivered to subscribers for a

familiar experience.

However, the advantage for the operator deploying NGN technologies is the opportunity

to offer applications provided through SIP application servers. SIP application services

have different characteristics than the IN services and can potentially unlock

opportun ities to increase subscriber ARPU. The driving philosophy of IMS is to create

applications that blend shared components, such as presence, to maximize the

effectiveness of a servi ce while minimizing the cost and time to deploy. Successful ly

deploying orchestrated applications requires SCIM functionality which performs the

blended service orchestration.

Frost & Sullivan

11



Ultimately, carriers will need to mediate services from IN and SIP domains to attain the

best reception from subscribers. Therefore, the SCIM not only assumes the role of

orchestrating applications, but also of mediating multiple services across various

technologies . The enablement of a cross-generational SCIM creates the opportuni ty forservi ce blends that can be seamlessly offered to any subscriber at any location. A

purpose-built SCIM solution should be able to orchestrate applications and mediate

servi ces between multi-technology networks. Additionally, the SCIM solution should

support a rules-based execution engine that enables providers to flexibly control service

interaction and mediation within and across networks.

Although the use of a SCIM solution in networks can be advocated for several use cases,

we will focus on two main cases:

1. Service Mediation in Intelligent Networks

2. Service Orchestration with Mediation across IN, NGN and IMS Networks

Service Orchestration and Mediation in Intelligent Networks

SCIM technology enables operators to solve real-world challenges that they face in their

networks today and creates a clear migration path to the future.

Operators are presently faced with hybrid networks containing products from multiple

vendors, using variants of the same protocols or completely different protocols, as in the

case of SCPs using either WIN or CAMEL. Inter-working and blending resources in this

environment using current technology is expensive and inefficient, and it hinders an

operator’s ability to deliver mixed service packages to their existing subscribers.

Using SCIM, operators can launch multiple services with a single trigger. In this scenario,

SCIM, deployed between the switch and the application layer, acts as a virtual SCP. It takes

a single service request from the MSC and directs multiple service requests to the SCPs.

It then aggregates the responses and sends a single response to the switch.

SCIM creates a new model for inter-working IN services when deployed between the

control and application layers. From this intermediary layer, the functions of mediation

and protocol conversion enhance the capabilities of the orchestration agent at the

application layer. This approach enables operators to integrate multiple applications built

on different protocols without re-architecting the network or upgrading the switchesand/or service control platforms.

For example, in GSM networks you could provide personal ring-back tones (PRBTs) to a

prepaid roaming subscriber – using a single trigger. In this scenario, SCIM, deployed

between the switch and the application layer, acts as a virtual SCP. The SCIM takes a single

service request from the MSC and directs multiple service requests to the SCPs. It then

aggregates the responses and sends a single response to the switch.

Frost & Sullivan

12



Service Orchestration with Mediation across IN and NGN and IMS Networks

In pre-IMS and IMS networks, SCIM continues to perform all three functions: 1.) protocol

conversion so that the SCIM can talk with all types of application servers; 2.) Mediation,so that it can determine order and precedence of applications; and 3.) Orchestration to

blend applications that share information.

As carriers transition their networks, an important consideration is how to inter-work

their existing networks with future IMS networks to deliver a seamless service

experience to subscribers regardless of their access technology. Operators want to

leverage their investment in current technology and avoid duplicating services in multiple

domains. In addition, providers need the ability to mix servi ces from multiple domains to

create unique service packages.

SCIM bridges TDM, NGN and IMS networks, providing the orchestration and mediation to

enable SIP-based application servers and IN service platforms to inter-work (please refer

to Figure 6). Th is allows carriers to deliver SIP-based services such as presence, location,

enhanced VPN and IP conferencing to SS7-based subscribers. Conversely, IMS subscribers

have access to SS7-based applications like number portability, directory assistance and

calling-name delivery.

Figure 6: Service orchestration and mediation between IN, NGN and IMS

Networks

Source: Tekelec

Frost & Sullivan

13

Vendor 1

MSC/SSP

Vendor 1

MSC/SSP

BillingControl

Billing

Control

PRBT PRBT

VPN/NPVPN/NP

CAMEL, WIN &

INAP with vendor

specific extensions

Expensive to Add Multiple Protocols

Vendor 2

MSC/SSP

Vendor 2

MSC/SSP PresencePresence

SIP App

Server

SIP App

Server

SIP

SoftSwich/

CSCF

SoftSwich/

CSCF

New Network Services

I n t e r a c t i o n

Virtual

SCP

Virtual

SCP

HLRHLR

HSSHSS

MAP, LDAP

&

Diameter

M e d i a t i o n

Virtual

SIP

AS

Virtual

SIP

AS



After the SCIM functionality is deployed at the STP in the SS7 network, operators can

extend the SCIM capabilities to the pre-IMS/NGN and IMS domains with a SIP interface.

This is a logical interconnection point since the SS7 network is the backbone for

intelligent service delivery, data and application interaction, and flexible routing in circuit-based networks.

With SCIM deployed in an NGN or IMS network, its functionality can be extended to an

SS7 network using SIGTRAN, an SS7 over IP signaling protocol. Deploying SIGTRAN

brings the IP service infrastructure into the core signaling network, allowing SIP and SS7

signaling to be processed over the same IP signaling framework. This arrangement allows

users on SIP-based terminals to access legacy network services and interact fully with

legacy network users.

Tekelec’s SCIM Solution

The Tekelec TekSCIM Service Mediator solution enables service interaction between

legacy, mobile, VoIP and IMS networks. It bridges technologies, allowing SS7-based, IN

service platforms to coexist and interact with SIP-based platforms to deliver unified

servi ces across vir tually any network type. With TekSCIM, operators can:

• Consolidate mediation and inter-working of IN service platforms with different

technologies and protocols

• Coordinate and manage the interaction of multiple applications to support

“blended services” in pre-IMS networks

• Extend IN services to the NGN/IMS domain and deliver next-gen, SIP-basedservices to traditional TDM subscribers

• Mediate multiple services in the IMS domain to create a rich, multimedia user

experience

GRADUALLY DEPLOYING AN IMS ARCHITECTURE

One of the key assumptions made for this paper is that the IMS architecture is the target

architecture. So what is IMS? IMS is a framework for building multimedia applications

over IP, with a specified archi tecture, interfaces, protocols and procedures. IMS was born

in the wireless and Internet domains – 3GPP, 3GPP2 and the IETF. However, IMS isbecoming increasingly applicable to wireline (TISPAN) and cable operators (Packet Cable),

who are leveraging the core IMS specification to develop complementary specs that

address their specific network, service and operational requirements.

In Figure 7, we see that the IMS Architecture has many characteristics and concepts in

common with the Intelligent Network (IN) architecture that is an overlay on the PSTN

and with the Customized Applications for Mobile Enhanced Logic (CAMEL) architecture

Frost & Sullivan

14



that is an overlay on the GSM mobile network. In fact, the IMS Service Control (ISC)

interface adopts many of the concepts of the SS7 IN, including trigger points.

Figure 7: Similar Concepts: IN – GSM – IMS

Source: Tekelec

Tekelec IMS Solution: Open IMS Alliance

Tekelec has elected to partner with HP, BEA Systems and third-party independent

software vendors (ISVs) and form the Open IMS Alliance, in order to accelerate the

deployment of IMS Services . The Open IMS Solution provides the first open, standards-

compliant and end-to-end IMS Solution within a cohesive, integrated infrastructure and

service environment.

Open IMS is an open, integrated and tested multi-vendor IMS offering that allows service

providers to address the challenges arising from decreasing sources of traditional revenue

and rising infrastructure costs. The solution includes IMS core network infrastructure,

service enablers, operational and business support system linkages and application service

offerings that enable the delivery of subscriber-centric services including fixed, mobile and

cable broadband networks.

Frost & Sullivan

15

SCPSCP

HLR HLR

SCPSCP

Provisioning

Trigger

Details

INQuery

CSI

CamelQuery

IN overlay

on PSTN

HSSHSS

ASAS

Profile

SIP

Query

Camel overlay

on GSMIMS overlay

on MM-NGN

SSFSSFIFCIFC

VLR/SSF VLR/SSF

Switch MSC

Bearer Bearer Bearer Bearer

Bearer Bearer

CSCF

MGCF/MG



Open IMS is illustrated in the next figure. The key components of the overall solution

include the following:

Figure 8: Open IMS Solution – Tekelec, HP, BEA Systems and third-party ISVs

Source: Tekelec

• Cal l ses sion control function (CSCF): TekCore is a Tekelec developed, 3GPP

compliant element providing CSCF capabilities to enable the control of next-

generation multimedia traffic . TekCore also delivers session initiation protocol

(SIP) signaling router functionality, allowing operators to cost-effectively upgrade

their next-generation networks (NGNs) to IMS

• Home subscriber server (HSS): The HP OpenCall HSS is derived from the HP

OpenCall Home Location Register, which provides mobility management for 35

servi ce providers and more than 200 million subscribers. As a core building

block in IMS networks, the HP OpenCall HSS acts as the master database for

both 3G and IMS subscribers, providing service data, feature lists and subscriberinformation.

• SIP application server (AS): The BEA WebLogic SIP Server, the SIP-IMS

application server component of the BEA WebLogic® Communications Platform

product family, provides a high-performance, available and powerful service

creation and execution environment designed for converged Internet-IMS

communication and collaboration ser vices.

Frost & Sullivan

16



• Service enablers: including the media resource function (MRF), presence server,

electronic numbering (ENUM) and group list management

• Multimedia applications: such as enhanced voice services, instant messaging (IM)and video sharing

• Systems integration: Integration with back-office and legacy systems

Leveraging a variety of IMS service enablers running on top of the HP-Tekelec IMS

infrastructure, the BEA solution is designed to provide a highly flexible, customizable and

expandable services environment for Independent Software Vendors (ISVs), Network

Equipment Vendors (NEVs) and System Integrators (SIs) deploying revenue-generating

voice, data and content services. The joint solution provides a cohesive, integrated

infrastructure and service environment, delivered as a whole with expansion and

enhancement options provided to meet or fit service providers’ needs.

In order to support customer requirements for fully integrated solutions, the companies

have successf ully completed interoperability testing between the Tekelec TekCore Session

Manager (CSCF), the HP OpenCall home subscriber server (HSS) and the BEA

WebLogic® SIP Ser ver. In addition, Tekelec is also a ver y active par ticipant in

interoperability testing (IOT) efforts being led by organizations such as the IMS Forum

and SIP Forum.

ENSURING ALL SIP ISSUES ARE ADDRESSED

Undeniably, SIP (Session Initiation Protocol)3 is one of the hottest specifications du jour,

offering some key intangibles such as support for multimedia call set up, and having been

incorpora ted into the recent standard for NGN and IMS based signaling. In fact, SIP is

already being used in applications that go above and beyond the original intent, yet it has

evolved to meet the requirements of these unanticipated uses. Today SIP is used as:

• a network access protocol to enable user-to-network call signaling

• as a core network protocol to enable call setup

• as a network-to-network call setup protocol

• as a service and application control protocol

Issues with SIP can potentially emerge before, during and after all of the NGN and IMS

elements are deployed. In terms of signaling, a fundamental distinction between SIP and aprotocol such as SS7 is the part of the signaling network each was originally intended for.

SS7 was designed to be a core network signaling protocol and as such is very robust and

resilient to failures.

Frost & Sullivan

17

3. SIP is defined in RFC 3261 from the IETF (Internet Engineering Task Force). Pleaserefer to: http://www.ietf.org/rfc/rfc3261.txt



By contrast, SIP was originally designed to operate between VoIP endpoints, as shown in

Figure 9:

Figure 9: Initial SIP application - endpoint to endpoint call setup

Source: Tekelec

Defining a prompt recovery mechanism for failure scenarios was not a design goal for SIP.

Since SIP was targeted for endpoint to endpoint communication, and since failure of

either endpoint would result in a session failure, there was no need for recovery

mechanisms.

In NGN and IMS networks, SIP is no longer restricted to signaling between endpoints –

instead SIP is used for signaling between network elements at the core of the network.

In these scenarios, for instance, it is not acceptable for the failure of an S-CSCF to result

in failure of the session. Rather, it is expected that failure will result in a failover to

another S-CSCF that is also associated with the failed S-CSCF as illustrated in Figure 10.

Issues that have been overlooked by ongoing standardization efforts include the

achievement of high availability of SIP servers and failure or overload detection within the

core SIP signaling network. Within its product portfolio, Tekelec has tackled these issues

by providing solutions that enable geographic redundancy and monitoring of SIP endpoints

via “reactive heartbeats” to detect fail ures at the SIP layer. Tekelec has developed i ts

“TRUST” package to address the issues associated with using SIP as the signaling protocol

for the core of the network. The TRUST package improves robustness and resiliency to

failure of a core signaling network that i s based on SIP. Geographic redundancy, failure

detection and tuned timers are key competitive differentiators for Tekelec’s TRUST

package, since they are not usually found in other vendor’s products.

Frost & Sullivan

18

IP

Media Stream



Figure 10: SIP in the Core of the signaling network

Source: Tekelec

Bandwidth Inefficiency of SIP in a Wireless Environment

SIP was designed for simplicity and easy troubleshooting, not for bandwidth efficiency. The

initial use of SIP was on wireline networks that supported broadband speeds, where

bandwidth was, relatively speaking, abundant. However, wireless networks are different

and bandwidth over the radio access network is not unlimited. A comparison between

SS7 signaling and SIP based signaling is captured in the figure below.

Frost & Sullivan

19

P-CSCF

S-CSCF S-CSCF S-CSCF

SIP

AS

SIP

AS



Figure 11: Signaling Intensity Expands Dramatically with IMS

Source: Tekelec

As the figure indicates, using SIP for signaling increases the size of the messages as well as

the number of messages – resulting in a significant impact on the signaling control layer.

Hence, the evolution to IMS and new services will significantly increase the number of

messages compared to traditional telephony services . This factor significantly impacts thedesign of the signaling network, especially if SIP is used at the handset or user device.

The issue of message size is particularly important for the air interface. The standards

bodies have addressed this issue by defining RFC 3320 Signaling Compression (SigComp)

as well as an Internet Draft RFC titled “Applying Signaling Compression (SigComp) to the

Session Initiation Protocol (SIP) Standard.” Carriers that intend to send SIP over the

radio access interface should cons ider using SigComp. Tekelec has gained significant

experience with SigComp during IMS trials in wireless environments. Leveraging its

expertise in SS7 signaling, Tekelec has implemented several new, patented technologies on

its TekCore product, which brings the best attributes of SS7 to SIP.

Another challenge arising from the high traffic increase due to SIP is overload

management at the control plane. Unlike SS7, which exchanges network management

messages between nodes, there is no similar concept in SIP. There is no current work

underway in the IETF, however, the Multi-Service Forum (MSF) as well as the TISPAN

(Telecoms & Internet converged Services & Protocols for Advanced Networks) standards

groups, are investigating ways to address these issues. The Multi-Serv ice Forum has

recently published a paper on this topic (MSF-TR-ARCH-007-FINAL: NGN Control Plane

20

Frost & Sullivan

‘07 | 23

*Tekelec Analysis

Signaling

Intensity ExpandsDramatically withIMS …

0 10 20 30 40 50

IMS (FMC)

IMS (Basic)

POTS Call

Number of Messages Per Service

… and Signaling

Message Sizes

Increase as Well

POTS IMS (Basic)

Msg Type Bytes Msg Type Bytes

IAM 60 Invite 1000

CPG 20 100 Trying 300

ACM 20 180 Ringing 700

ANM 20 200 OK 1000

ACK 500

REL 20 BYE 500

RLC 20 200 OK 400

TOTALS 160 4400



Overload and its Management). Tekelec’s use of DNS Caching and Exception List helps

eliminate unnecessary requests to downed SIP servers and is one way to reduce

congestion in the network in failure scenarios.

THE SEARCH FOR THE BEST TRANSITIONAL STRATEGY

Table 1 shows that operators have several solution alternatives to chose from from in

addressing the earlier mentioned challenges, and the eventual migration to IMS. One

alternative would be to migrate all existing network services and applications over to the

new SIP infrastructure, a logistical and financial nightmare. Another option would be to

add SIP to all existing SCPs, which would be another costly and unrealistic opt ion. A

third, less costly and disruptive option is to use transitional technologies, like service

mediation, to provide a “bridge” between the SIP-based IMS network and SS7-based PSTN

and 2G mobile networks. Implementing a transitional strategy based on the signaling

control layer appears to be the most promising option. Bridging technologies can be used

between the SS7- and SIP-signaling networks. A close linkage of the STP and CSCF can

facilitate a more graceful and cost-effective migration to IMS.

Table 1 - The best transitional strategy is migrating at the signaling layer

Source: Tekelec

A key part of an operator’s transition strategy is to start from the IN control layer, and

pursue a service mediation solution between the SS7-based TDM and legacy fixed/mobile

networks, and the SIP-based IMS network. This “bridge” will allow SIP-based terminals to

access legacy PSTN/2G services and allow PSTN/2G terminals to access (some) IMS

servi ces, thereby reducing service replication costs. Hence, this strategy will deliver

revenues from existing subscribers to help fund the capital expenditure that will be

Frost & Sullivan

21

Implementation Alternatives Outlook?

Transitional strategy based on

the control layer.

Complete cutover to IMS? Not very realistic and way too costly.

Run parallel isolated networks? Would result in “islands of IMS.”

Upgrade legacy equipment to

handle IMS/SIP interfaces?

Requires a lot of investment in legacy

equipment rather than in next-gen

equipment.

Replicate existing services

into the IMS Domain?

Very costly and not a good use of next-

gen investment dollars.

Custom build our own solutions?This is a big undertaking – could be very

costly and time consuming.

Looks like the most logical solution …



needed to pay for the evolution to the IMS. A transitional approach, leveraging service

mediation to create a unified signaling layer (see Figure 12), will help operators:

• Minimize investment in “pre-IMS” technologies• Provide service continuity across hybrid networks

• Lower costs by leveraging existing investment in key IN/AIN applications for

both domains during transition to IMS

There are additional advantages of the service mediation approach over alternative

solutions . Centralizing mediation intelligence at the signaling core eliminates the need for

costly network upgrades or overhauls. Also, the same service mediation model and

equipment can be re-used for other services and mediation issues.

Figure 12: Unified Signaling Layer Accelerates Migration

Source: Tekelec

SUMMARY AND CONCLUDING REMARKS

Signaling is embedded in every service today and will continue to be in the future.

Industry drivers and technology trends are changing rapidly, creating new business and

network challenges for operators . The core signaling and session cont rol layer, which hasproven its importance in the SS7 signaling network, is identified in the IMS network

architecture and will soon be introduced into the NGN to support the expansion of VoIP

and a new generation of multimedia services.

While the transition to IMS appears to be the end goal, the path and length of time to get

there are unknown at this point in time. The reality is that operators are borrowing the

Frost & Sullivan

22



best of IMS today to get the most benefits possible, without deploying a full-blown IMS

infrastructure, which causes the IMS business case not to work that well. The incremental

approach being taken by operators allows them to prove-in the IMS business case much

easier than just building the entire IMS infrastructure and waiting for the subscribers andrevenues to come.

One thing is clear: the move to IMS will be a gradual transition over time, requiring the

interplay of different network applications, technologies and protocols as the networks

evolve. The key to success in this complex and competitive environment is to understand

how the evolution of the network will impact a service provider’s business and signaling

network, and how to create a good transitional strategy.

In this paper, we made a case that the most logical transitional strategy is one that is

based on the control layer. By leveraging its exper tise in signali ng, Tekelec has a unique

angle of attack for the IMS marketplace. This is in contrast to its other competi tors, such

as the large network equipment providers (NEPs) that typically try to leverage their

acumen in legacy switching products as they tackle the transition towards IMS. These

vendors try to position the central office switch as the optimal point from which the

network should evolve. The NEPs pitch to “upgrade” their softswitches to a CSCF is a

somewhat risky proposition, as it inevitably leads to vendor lockdown (due to the

proprietary nature of most switching implementations), and possibly even some scalability

issues and other performance bottlenecks (as the IMS network begins to increase).

Another key pitfall associated with a softswitch-based architecture is the lack of a core

signaling infrastructure, which can cause scalability and availability issues, routing and

service complexity, increased interoperability testing and higher operation costs

associated with NGN expansion.

By contrast, Tekelec, given its signaling expertise, maintains that signaling is the obvious

starting point of the evolution of the network. As a result, the company developed the

TekCore SIP Signaling Router (SSR). TekCore SSR introduces an independent SIP signaling

and session control layer in the NGN that can respond to increasing demand for VoIP, as

well as support multimedia services. A session framework also offers an excellent

opportunity to introduce the benefits of IMS architecture into the NGN environment.

With the appropriate signaling and session control framework the NGN network can

realize many of the attributes promised by the IMS architecture, without the cost of

deploying a full blown IMS infrastructure.

IMS is moving forward in a variety of ways, albeit slower than originally forecasted. Part

of the reason for this is the fact that operators are still grappling with how best to

migrate their network and services to IMS, and how to make the IMS business case work.

With Tekelec’s TekSCIM solution, carriers can harnes s the power of IMS technology in

their networks today to deliver innovative mixed service packages AND create a clear

migration path to the future.

Frost & Sullivan

23



In the final step, operators will deploy an IMS-compliant, SIP-based CSCF, similar in role

to the STP in TDM networks. To overcome the initial barriers to deploying IMS, Tekelec

has teamed with HP, BEA Systems and third-party independent software vendors (ISVs) to

create the Open IMS Solution - to accelerate the deployment of IMS Services. The OpenIMS Solution provides the first open, standards-compliant and end-to-end IMS Solution

within a cohesive, integrated infrastructure and servi ce environment. Furthermore ,

TekCore incorporates several new, patented technologies that will bring the best

attributes of SS7 to SIP.

Finally, via strong partnerships with the more innovative vendors, operators can ease the

transition by staying attuned to emerging issues, and can work with their vendors to meet

these challenges before they arise. Given the expertise that it has developed in the SIP

domain, Tekelec is well positioned to address performance issues related to the increased

traffic due with the advent of IMS. Key differentiators by Tekelec in this area include

geographic redundancy, failure detection and tuned timers.

Summarizing, Tekelec supports a multi-prong strategy for helping operators migrate to the

next-generation service delivery model at their own pace and via the path that best suits

their needs:

• For those who want to gradually move into IMS while continuing to leverage

everything they’ve already deployed, there is TekSCIM, which supports service

orchestration and mediation across the IN, NGN and IMS domains.

• For operators who want to continue building out their NGN to support VoIP

growth, but who also want the benefits of IMS without the cost of deploying the

entire architecture – there is the TekCore SIP Signaling Router (SSR).

• For carriers who want to go straight to IMS or who want to deploy IMS-based

applications, there is the Open IMS Solution with Tekelec’s TekCore CSCF, HP’s

OpenCall HSS, BEA’s WebLogic SIP Application Server and third-party ISVs.

Frost & Sullivan

24



877.Go

myfrost@fros

http://www.fros

Silicon V

2400 Geng Road, Sui

Palo Alto, CA

Tel 650.47

Fax 650.475

San An

7550 West Interstate 10, Suit

San Antonio, Texas 78229

Tel 210.34

Fax 210.348

Lo

4, Grosvenor Ga

London SWIW OD

Tel 44(0)20 7730

Fax 44(0)20 7730

CONTACT

US

ABOUT TEKELEC

Tekelec is a high-performance network applications company that is enabling the transitio

IP Multimedia Subsystem (IMS) networks for service providers around the globe. With

experience at the intersection of network applications and session control, Tekelec cre

highly efficient platforms for managing media and delivering network solutions. Corpo

headquarters are located near Research Triangle Park in Morrisville, N.C., U.S.A., with rese

and development facilities and sales offices throughout the world. For more information, pl

visit www.tekelec.com.

ABOUT FROST & SULLIVAN

Frost & Sullivan, a global growth consulting company, has been partnering with clients to

support the development of innovative strategies for more than 40 years. The company's

industry expertise integrates growth consulting, growth partnership services and corporat

management training to identify and develop opportunities. Frost & Sullivan serves an exten

clientele that includes Global 1000 companies, emerging companies, and the investment

community, by providing comprehensive industry coverage that reflects a unique global

Palo Alto

New York

San Antonio

Toronto

Buenos Aires

Sao Paulo

London

Oxford

Frankfurt

Paris

Israel

Beijing

Chennai

Kuala Lumpur

Mumbai

Shanghai

Singapore

Sydney

Date post:	06-Apr-2018
Category:	Documents
Upload:	sanjeev-kumar
View:	217 times
Download:	0 times

Network Evolution - Migration Strategies for Success-FINAL

Documents