The Evolution of Signaling

Dan Rothschild

Director, Engineering

Slide 2

Contents

� Signaling Evolution Overview

� SS7 Status

� Sigtran

� Bearer Independent Call Control

� Converged Networks

� NMS Signaling Products

Slide 3

Signaling Evolution Overview

1990 2000 2007

Bearer Independent Call ControlBICC

Sigtran: SS7/IP

Call Control

Network Services:800, Calling Name, LNP

Wireless: Mobility, Roaming, SMS

IN: Prepaid, Call Mgmt, Ringback

High Speed Links

SS7

…

Converged Networks

IP Core IMS Multi-Access

SIP H.248 Diameter

Slide 4

Signaling Evolution Drivers

� Signaling bandwidth requirements for new services

� SMS, MMS

� Number portability

� Push-to-talk, voice call continuity

� Presence, location

� Transport evolution from TDM to packet

� IP/Ethernet everywhere

� Lower cost, higher bandwidth

� Protocol explosion in standards bodies

� IETF: SIP, SIP-T, SIMPLE, SIGTRAN

� 3GPP: R99 (UMTS) , R4 (IP-core), R5, R6, R7 (IMS), ….

Slide 5

Signaling Evolution Stages

� Starts in core network

� Highly utilized routes replaced for bandwidth/cost reduction

� Small number of nodes updated/replaced

� Sigtran or BICC deployed here first

� Evolves to access networks

� For new services and/or bandwidth

� Interworking with new networks

� More equipment impacted: switches, gateways, DSLAMs

� Migrates to edge devices last

� New service deployments

� Enhanced service platforms, application servers, media servers

Slide 6

Overview of SS7

� Circuit-switched call control: ISUP, TUP

� Non-circuit services: TCAP, SCCP� IN-service protocols: INAP, AIN, CAMEL

� Wireless services: MAP — mobility, HLR, roaming, SMS

� Network-based services: 800, calling name, LNP

� Signaling Transport: MTP layers 1-3� Optimized for 48/56/64 kbps links

� High-speed links (full T1/E1) introduced for high-bandwidth paths

� Widely deployed in nearly all networks� Wireline and wireless

� New service deployments still occurring

Slide 7

SS7 Protocol Architecture

MTP Layer 1

MTP Layer 2

MTP Layer 3

SCCP

IS-634/BSSAP

TCAP

MSC

ANSI-41

HLR

GSMMAP

INAP/CAMEL ISUP/

TUP

BSSService

Node

Transport layers

Upper layers

Slide 8

SIGTRAN — What is it?

� Transport of upper layers of SS7 in IP packets

� Replaces the transport layers of SS7 (MTP, SCCP)

� Sigtran Architecture Components

� SCTP — Stream Control Transmission Protocol

� Reliable transport for signaling

� Adaptation Layers — many different ones available

� Resides on both SG and IP Node

� Inter-working function on SG

� Mapping between IP addresses and SS7 point codes

� Multiplexing SS7 interface to multiple IP Nodes

� ISUP, TCAP reside on IP Node

� (Optional) IPSEC on IP node and SG

Slide 9

SCTP Protocol Characteristics

� Reliable transport layer

� Connection oriented

� Multiple control “streams” per port

� In-sequence delivery within a “stream”

� Supports multi-homing with fail-over

� TCP-like congestion avoidance

� Addresses some of TCP’s limitations

� High fan-out (large number of connections)

� Fast detection of failures

Slide 10

Sigtran Adaptation Layers

� One for each different signaling protocol

� MTP-2 adaptation layers (M2UA/M2PA)

� MTP-3 adaptation layer (M3UA)

� SCCP adaptation layer (SUA)

� Provides status and network management services in addition to data transfer

� Upper adaptation layers support various redundancy models

� Primary/backup

� Load sharing

Slide 11

Packet NetworkPSTN/SS7

PC=10-1-30IP=1.2.3.10STPSTP

SSP

SSP

STPSTP

IP

SCTP

M3UA SUA

ISUP TCAP

Application

MTP2

MTP3

IP

SCTP

SCCP SUA M3UA

IWF

SGSG

PC=10-1-255

PC=10-1-10

PC=10-1-20

PC=10-1-1

IP=1.2.3.3

IP=1.2.3.2

IP=1.2.3.1

MGC

MGC

MGC

Simple Distributed Gateway Architecture

Slide 12

Current Real World Deployments

� AT&T (Cingular)� Used M2PA for STP-to-STP hauling of SS7 links

� Future plans included:

� M3UA for MSCs, SMSCs and SCPs

� Vodafone Ireland� SMSCs

� KPN/Netherlands� To prepare for IMS infrastructure

� China Mobile� SMS traffic again the driver

� Just a few examples

Slide 13

BICC Overview

� Bearer Independent Call Control

� Extension to SS7 ISUP for setting up calls over packet bearer networks

� Can be transported over

� SS7 MTP3 or MTP3-b (ATM)

� Sigtran M3UA/SCTP

� Actual bearer setup protocol can be transported independently or tunneled over BICC itself

� For RTP/IP bearer networks, SDP can be tunneled over BICC to set up RTP connection

� Competes with SIP-T for core network call control

Slide 14

BICC Capability Sets

� Capability set 1 (Q.1901)

� Basic call control, ATM-orientation

� Forward or Backward Bearer Setup

� Codec negotiation + mid-call codec modification

� Tear-down bearer at end of call or keep for re-use on another call

� Capability set 2 (Q.1902.x)

� IP bearer set-up support

� Bearer protocol tunneling

� Supplementary services

� Extension to special resource nodes, via H.248

Slide 15

BICC Call Setup with tunneled SDP bearer setup

(forward bearer setup)

PSTN-TMCG/MGMGC/MGPSTN-O ISUP

Bearer Established

ISUPBICC

IAM

IAM (connect fwd)

(tunneled SDP Offer)

IAM

ACM

APM (connect fwd)

(tunneled SDP Answer)

APM (connected)

[optional]

ACM

ACM

ANMANM

ANM

Note: Many other flows possible

Slide 16

Gb/IuPS

A/IuCS

SS7

IP/ATM

BTS

BSCMSC Server

VLR

HSSAuC

GMSC server

BSS

SGSN GGSN

CN

C

D

Gc

Gr

Gn Gi

Abis

Gs

B

H

BICC in 3GPP rel5 Architecture:

MSC-Server to MSC-Server Interface (Nc)

2G MS (voice only)

2G+ MS (voice & data)

Node B

RNC

RNS

Iub

3G UE (voice & data)

CS-MGW

CS-MGWNb

PSTN

IuCS

IuPS

IP/ATM

IM

IPPSTN

MGCF

IM-MGW

MRF

CSCF

Mg

Gs

PSTN

McMc

Mc

PSTN

IP Network

Slide 17

Converged Networks

� Packet-switched IP core network (e.g., IMS)� Voice, video, data

� Common user profile (HSS)

� SIP is the dominant signaling protocol

� Common services independent of:� Access network

� Location

� Device

� Interworking with multiple access networks� Circuit switched and packet switched

� Wireless, broadband, 2G, 3G, ….

� Proliferation of protocols can be challenging…

Slide 18

Example: 3GPP MSC Server Stacks

MTP

ISUP

L1

ATM

CPS AAL5

SSCOP

SSCF-NNI

MTP3b

SCCP

TCAP

MAP

L1

ATM

CPS AAL5

SSCOP

SSCF-NNI

MTP3b

H.248

L1

ATM

CPS AAL5

SSCOP

SSCF-NNI

MTP3b

PSTN

C

HLR

Cl.5/4

Mc

Nc

L1

ATM

CPS AAL5

SSCOP

SSCF-NNI

MTP3b

RANAP

MM

CC/SS/SMS

To User Equipment

IuCSIuCS

SAAL

-NNI

Q.2150.1

AA

To Mobile StationL1

MTP2

MTP3

SCCP

BSSAP+

GsGs

MTP

SCCP

BSSAP

MM

CM

L1

L2

IP v6/v4

SCTP

M3UA

L1

L2

IP v6/v4

SCTP

M3UA

L1

L2

IP v6/v4

SCTP

M3UA

SCCP

BICC

BSSAP BSS Application Part — GSM 08.08 / 08.06

ISUP ISDN User Part — ITU Q.76x

M3UA MTP3 User Adaptation — RFC 4666

MAP Mobile Application Part — GSM 09.02

MTP Message Transfer Part (1,2,3) — ITU Q.70x

MTP3b Message Transfer Part over ATM — ITU Q.2210

RANAP RAN Application Part — TS 25.413

SAAL Signaling AAL — ITU Q.2100

CC/SS/SMS Call Control, Supp Serv, Short Message Service)

MM Mobility Management

SCCP Service Connection Control Part — ITU Q.71x

SCTP Stream Control Transport Protocol — RFC 2960

SSCF-NNI Service Specific Coord. Function — ITU Q.2140

SSCOP Service Specific Connection Oriented Protocol — ITU Q.2110

TCAP Transaction Capabilities Application Part — ITU Q.77x

Slide 19

NMS Network Signaling Support

Natural Access

ISDN/CAS

TX 4000TX 4000CTX 4000e

SIP SS7ISUP BICC TCAP

SigtranM3UA

MTPTDM

VisionSignaling

Server

Slide 20

SS7 Signaling BoardsTX Series

� Support for a full 32 SS7 links and up to 4

high-speed links (HSL)

� Software-selectable T1 or E1 (120 ohm)

trunks

� Full node-level redundancy for high

availability

� On-board software, freeing host computer

� Protocols meet telephony standards,

compatible with all major switches

� Variety of form factors and density

� Part of the Open Access family

� Powerful and flexible solutions for global

SS7 applications

Features

Value Proposition

Benefits

� Leverage NMS’s worldwide SS7

expertise

� Scalable hardware with minimum host

loading

� Rich and robust API with ITU, ANSI

standards

� Competitively-priced, flexible licensing

TX SeriesSignalingBoards

Slide 21

Vision Signaling Server

� ISUP (ITU and ANSI) signaling for call control

� 4, 16, or 32 low-speed signaling links (DS0s)

� 4 high-speed links (HSL) (DS1s)

� Carrier-grade

� NEBS-compliant

� Redundant, fault tolerant configurations

� AC or DC powered

VisionSignaling

Server

Slide 22

SIP for Natural Access

� Uses the Natural Access NCC Service, API

� Common programming model simplifies application development

� Supports important extensions for services, such as call transfer, call hold, and auto attendant

� Works with the VoIP service to establish media path connections to Natural Access’ rich media processing resources

� Implemented with RADVISION SIP stack

SIP

Slide 23

ISDN/CAS

� Broad range of TDM signaling protocols

� ISDN — 11 variants including Euro-ISDN, QSIG ECMA 143, NI-2, Lucent 5ESS

� Channel Associated Signaling (CAS)

� Worldwide MFC-R2 variants

� Many others including CAS R1.5, winkstart, SS5, OPS/OPX,

European CAS, digital E&M

� Multiple versions of CAS and ISDN can run on a board

� Selectable during runtime

� On-board execution enables efficient call processing while offloading the host CPU

PSTNTrunking

Slide 24

Summary

� Signaling network evolution towards converged, SIP-based networks is underway

� Transition will take many years

� Operators must leverage existing installed base of SS7 services and equipment

� For the next several years, transition technologies are needed to bridge the gap between today’s service architectures and converged networks

� NMS signaling products can help smooth the transition

Slide 25

Questions?

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