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Transcript of 1 © 2001, Cisco Systems, Inc. Technology Overview - Voice Gateway SS7 Interconnect for Voice...
1© 2001, Cisco Systems, Inc. Technology Overview - Voice Gateway
SS7 InterconnectSS7 Interconnectfor Voice Gatewayfor Voice Gateway
Key Technologies for PSKey Technologies for PSProject and Program ManagersProject and Program Managers
Created and Presented by Steve WellsCreated and Presented by Steve Wells
2Technology Overview - Voice Gateway
What’s an SS7 Voice Gateway?
Why’s that important?
What’s it all about?
• Challenges
• Concepts
• Components
• Layout
SS7 Interconnect forSS7 Interconnect forVoice GatewayVoice Gateway
3Technology Overview - Voice Gateway
The Changing WorldThe Changing World
Telecommunications is undergoing rapid change.
The infrastructure is Old World.
The needs and opportunities areNew World.
POTS and PANSPlain Old Telephone Service
Pretty Amazing New Services
4Technology Overview - Voice Gateway
Old World InfrastructureOld World Infrastructure
Voice network and data networkon the same wires.
• Circuit switched lines.
• Voice traffic on voice lines.
• Packet data on voice lines.
• Optimized for voice.
• Voice calls average 6 minutes.
5Technology Overview - Voice Gateway
New World ChallengesNew World Challenges
1980’s and 90’s - traffic growth
• Voice grew linearly.
• Data grew exponentially.
• Now: data traffic = 5 × voice traffic.
• Data traffic: brief bursts, then quiet.
• Data on voice lines wastes bandwidth.
• Calls average 32 minutes.
6Technology Overview - Voice Gateway
New World ObjectivesNew World Objectives
Data on packet data lines.Voice as packet data (VoIP).Optimize for data.
Statistical multiplexing provides efficient bandwidth use.
Business NeedsConsolidate 2 networks (voice and data) into 1.Provide access for data calls.
Consumer MarketConsolidate entertainment (TV), telephone, and Internet access into one communications network.
7Technology Overview - Voice Gateway
Switching Network
Line Concentration
Digital Trunk Subsystem
Call ControlConnection Control
Features
Common ChannelSignaling Complex
AdministrationMaintenance
Billing
TDM Switchby SNALE TDM Switchby SNALE
Services PlaneIN Service Logic AAA, Address Resolution
ServiceLogic
Open Packet TelephonyOpen Packet TelephonyOpen Packet TelephonyOpen Packet Telephony
SCP Partners
VCO4K
UnifiedComm.
VSCSignaling Controller
Call Manager
IN / AIN / CTI
Call Control PlaneSignaling and Call ControlService Access FunctionSwitch-Based Service LogicEnd-to-End VoiceServices
DefinitionConversionSimulatorConfigurationAnalyzer
InterworkingTool Set
CallLogic
Full Access to Existing and New
IN/AIN Products
Flat Efficient Transport Layer
User Programmable
Call Control
Connection PlaneConnection NegotiationTranscodingBearer SwitchingMedia Control: RTP, PNNI, Etc.
SwitchingLogic
MGCP / SIP / H.323
8Technology Overview - Voice Gateway
Signaling System 7Signaling System 7
Out of Band Signaling
• More signal data at higher speeds.
• Signals sent anytime.
• Signals to network elements with no direct trunk connection.
• Circuit resources are not used until the connection can be completed.
9Technology Overview - Voice Gateway
Signaling System 7Signaling System 7
Voice as Packet Data
• More voice data on fewer lines.
• Non-voice data can share the line.
• A voice packet can go down any trunk.No tying up dedicated switches to keep calls connected.
• Phones and calls with special features.
10Technology Overview - Voice Gateway
SS7 ArchitectureSS7 Architecture
SSP Service Switch Point Starts/ends callAccess end points and controls.Bridge unmated pairs.Cross to mate for reliability.Diagonal to another network.Extended to non-home pair.Fully associated Service Points.
A-Links - F-Links
PSTN SS7Signaling Network
BB
B B
BB
F
F
EE A A
A
A A
AAA
A A
D
D
D
CCCC
SSP SSP
SSP SSP
STP
STP
STP
STP
STP
STP
STP
STP
SCP
SCP
STP Signal Transfer Point Routes call
SCP Service Control Point “Specials” database
11Technology Overview - Voice Gateway
The technical challenges are immense.
Voice over IPVoice over IP
Performance must be great. Users will: Demand a high Quality of Service. Assume calls will stay connected. Count on phones to work during power failures. Hold fully duplex conversations. Presume privacy and security. Dial in to the Internet. Send and receive Faxes.
12Technology Overview - Voice Gateway
Voice over IPVoice over IP
Infrastructure Challenges
• Old wire.
• Existing electronics / hardware is getting old.Not state of the art.
Tired and failure prone.
• Huge investment and effort needed to install new lines and equipment.
13Technology Overview - Voice Gateway
Voice over IPVoice over IP
Security and Reliability Challenges• Callers must send and receive only their own
voice packets.
• DES Security -- Data Encryption Standard.
• IP phones must have battery backup, e.g. 4 hours.
• Low power consumption components for usewhile self-powered.
• Non-volatile memory to maintain phone functions.
14Technology Overview - Voice Gateway
Voice over IPVoice over IP
Latency (Delay) Challenges Accumulation Delay - to collect a frame of voice data.
Processing Delay - to convert a frame into packets.
Network Delay - to transmit packets across a network.
Polling Delay - till the head end asks for more packets.
Echo - must be cancelled with digital filtering.
Jitter - the packets don’t arrive at regular intervalsif they’re even in the right order!
Lost packets - must be interpolated or packets must have redundancy. Voice packets can’t be resent a few seconds later like lost internet data. (Think about it.)
15Technology Overview - Voice Gateway
Voice over IPVoice over IP
Phone Billing Challenges
Billing is handled by software call agents, routing through a voice enabled cable modem, or a utility box Broadband Telephony Interface.
Recurring line charges.
Local, long distance, and international calls with varying rates based on day, time of day, and actual connect duration.
Per use charges: directory assistance or call return.
Special per minute services:C++ Programmers’ Psychic Hotline
16Technology Overview - Voice Gateway
What makes VoIP possible? Digital Signal Processing (DSP) Hardware is
incredibly fast and getting faster!
Talented engineers at Cisco are top 10% people!
Voice over IPVoice over IP
Fax Challenges Precise timing is needed or the call will drop.
Lost data packets can drop the call, too.
Nobody said VoIP telephony was easy!
17Technology Overview - Voice Gateway
Solution ComponentsSolution Components
SLT
AS5x00
Signaling Controller
AKA: Cisco SC2200
Host
Signaling Link Terminal
AKA: SLT
Cisco Voice Gateway
Based on Sun Netra 1400s and
1800s
Based on 2611 w/ Special Cisco IOS Image for the SLT
Cisco IOS = 12.1(3)T
Based on AS5300 w/ 12.1(2a)T2 or Later
Supports over 60 Different ISUP Variants into
Q.931+ over IP
Supports Terminating A or F Links and
Encapsulating MTP 3 Layers and aboveover IP; Provides
Muxing F Links off E1s
H.323 Voice-over-IP Media Gateway Responsible for
Voice Packetization, H.323 Signaling
Diagram Description Details Purpose
Cisco SC2200
NodeCisco SC2200
Host
18Technology Overview - Voice Gateway
Universal Access ServersUniversal Access Servers
Low End Mid Range High End
Density
Cisco AS25008 or 16Async Ports
Cisco AS5300 (Access Server)4 or 8 T1/E1/PRI192/240 PortsAnalog/ISDN
CiscoAS5800(Access Server)48 T1/E1/PRI or2 CT3Up to 1440 PortsAnalog/ISDN
CiscoAccessPathTS3(Access Server)168 T1/E1/PRI4032/5040 PortsAnalog/ISDN
19Technology Overview - Voice Gateway
CPE Software Features
CPE Software Features
• PPP Multilink
• PPP extensions
DIAL ACCESS Software Features
DIAL ACCESS Software Features
• Integrated V.90 Modem & ISDN Support
• Dial Access Stacking Architecture (DASA)
• SS7 Integration
• AAA Support
• AAA
• Web Caching Via WCCP
• IGP Support/BGP Peering
• MPLS/Traffic Engineering
• IP QoS Support
• IGP Support/BGP Peering
• MPLS/Traffic Engineering
• QoS Support
POP Software Features
POP Software Features
CORE Software Features
CORE Software Features
Dial Internet Access Dial Internet Access Software FeaturesSoftware Features
DialPlatform
Cache
DistributionRouter
CoreRouter
IP CorePSTN
Layer 2Interconnect
20Technology Overview - Voice Gateway
SS7 Solutions ProvideSS7 Solutions Provide
• Opportunity for revenue sharing
• Service portfolio
A new interface for access servers
Allows selective acceptance of calls (white/black list screening)
• Target markets
Lower interconnect and capital costs enable down-market expansion
SS7 is often more readily available than PRI for faster time to market
• Geographic reach
Certain countries require SS7 interconnect
• Network scale
SS7 enables more revenue minutes per circuit (faster call setup time)
Cisco SC2200Cisco
SC2200
AS5X00AS5X00
VoIP Network
SS7Network
PSTN IMT
SS7 Links