Converged Networks Lecture 1 The Evolution of Telephony

Converged Networks Lecture 1: The Evolution of Telephony in the Enterprise © 2006 Cisco Systems, Inc. All rights reserved.

Basic Telephone System § A telephone system has four elements: A telephone set to convert sound to electrical signals and back to sound One or more central switching facilities Connections to the central switching facilities Connections among multiple switching centers across telephone networks § Subscribers connect to the telephone network using: Dedicated wire connections in overhead or underground cables Radio waves (cellular, satellite, or radiotelephone) Vo. IP © 2006 Cisco Systems, Inc. All rights reserved.

Basic Components of a Modern Telephone System Long Distance and International Connections IP Central Office with Switches Fiber Local Loop POTS and ADSL Home Office with Corporate VPN including Vo. IP © 2006 Cisco Systems, Inc. All rights reserved. Cellular Phone System

Traditional POTS Services § PSTN or PTT (POTS) has remained practically unchanged for over 100 years offering: Bi-directional, or full duplex, voice path to carry sound both ways at once Dial tone and ringing signals Subscriber dialing Operator services, such as directory assistance, long distance, and conference calling assistance Power © 2006 Cisco Systems, Inc. All rights reserved.

ISDN and T 1 Services § ISDN: A set of standards that allow data and voice to be carried on copper wire from the telephone exchange to customer premises: BRI: 2 B-channels and 1 D-channel for control PRI: 23 B-channels (30 in Europe) and 1 D-channel for control § T 1 Carrier System: Specification for digital transmission between telephone exchanges and sometimes directly to customer premises. T 1 uses copper wire or fiber. © 2006 Cisco Systems, Inc. All rights reserved.

Digital Telephone Services § Digital Telephone Services include: Voice mail Caller ID Call waiting Reminder calls (Three-way) conference calling Enhanced 911 (in North America) Centrex A number of other similar services © 2006 Cisco Systems, Inc. All rights reserved.

PBX and Centrex § Centrex (a virtual PBX): Call Transfer Call Divert – on no reply and on busy calls Call Waiting Three-Party Conference Call Pick Up (Group) Ring Back Reminder or Alarm Call Typical Centrex telephone. Note the Recall button and the Message Last Number Redial Waiting lamp. Centrex Hotline (non-dialed connection) Centrex Warm Line (delayed Hotline) Centrex Hunt Groups, with optional bypass numbers © 2006 Cisco Systems, Inc. All rights reserved.

Long-Distance Calling Challenges May I have a line to Chicago? Is this a business call? PSTN Yes it is. Thank you. One second please. Chicago Office PBX © 2006 Cisco Systems, Inc. All rights reserved.

Long-Distance and WATS § Long-distance trunk lines connect telephone exchanges. § Long-distance services include: OUT-WATS: Flat-rate long-distance calling IN-WATS: Toll-free calling using 1 -8 xx numbers © 2006 Cisco Systems, Inc. All rights reserved.

Separate Voice, Video, and Data Networks § London Office § San Jose Office PBX § Tokyo Office PBX © 2006 Cisco Systems, Inc. All rights reserved.

Converged Voice, Video, and Data Network PSTN IP WAN © 2006 Cisco Systems, Inc. All rights reserved.

Traditional Hierarchical Model © 2006 Cisco Systems, Inc. All rights reserved.

Cisco Enterprise Architecture © 2006 Cisco Systems, Inc. All rights reserved.

Campus Architecture combines a core infrastructure of intelligent switching and routing including: § IP Communications § mobility § advanced security © 2006 Cisco Systems, Inc. All rights reserved.

Data Center Architecture The Data Center is a cohesive, adaptive network architecture supporting: § requirements for consolidation § business continuance § security © 2006 Cisco Systems, Inc. All rights reserved.

Branch Architecture The Branch allows enterprises to extend head-office applications and services including: § security § IP communications § advanced application performance supporting thousands of remote locations/users © 2006 Cisco Systems, Inc. All rights reserved.

Teleworker Architecture § Teleworker architecture allows enterprises to securely deliver voice and data services to remote, small or home offices. © 2006 Cisco Systems, Inc. All rights reserved.

WAN Architecture § WAN architecture offers the convergence of voice, video and data services over a single IP communications network. © 2006 Cisco Systems, Inc. All rights reserved.

Example: Enterprise Network © 2006 Cisco Systems, Inc. All rights reserved.

Network Traffic Mix and Requirements § Converged network traffic mix: Voice and video traffic Voice applications traffic Mission-critical applications traffic Transactional traffic Routing update traffic Network management traffic Bulk transfer (best-effort) and scavenger (less-than-best-effort) traffic § Key requirements: Performance (bandwidth, delay, and jitter) Security (access and transmission) © 2006 Cisco Systems, Inc. All rights reserved.

Example: Integrated Services in a Converged Network © 2006 Cisco Systems, Inc. All rights reserved.

Intelligent Information Network (IIN) § IIN integrates networked resources and information assets. § IIN extends intelligence across multiple products and infrastructure layers. § IIN actively participates in the delivery of services and applications. © 2006 Cisco Systems, Inc. All rights reserved.

Phases of IIN § Three phases in building an IIN are: Integrate transport Integrate services Integrate applications © 2006 Cisco Systems, Inc. All rights reserved.

Cisco SONA Framework § Cisco SONA is an architectural framework. § Cisco SONA brings several advantages to enterprises: Outlines how enterprises can evolve toward the IIN Illustrates how to build integrated systems across a fully converged intelligent network Improves flexibility and increases efficiency § Cisco provides an extensive product line, services, proven architectures, and experience to help the enterprises achieve their business goals. © 2006 Cisco Systems, Inc. All rights reserved.

Cisco SONA Layers © 2006 Cisco Systems, Inc. All rights reserved.

SONA—Networked Infrastructure Layer § The goal is “anywhere/anytime connectivity. ” © 2006 Cisco Systems, Inc. All rights reserved.

SONA—Interactive Services Layer Interactive services includes: § voice and collaboration services § mobility services § security and identity services § storage services § computer services © 2006 Cisco Systems, Inc. All rights reserved. § application networking services § network infrastructure virtualization § services management § adaptive management services

SONA—Application Layer includes: § business applications § collaboration applications © 2006 Cisco Systems, Inc. All rights reserved.

Introduction to Vo. IP Lecture 1 Paul Flynn © 2006 Cisco Systems, Inc. All rights reserved.

Vo. IP Part 1 – Sept - Dec 1. Introduction 2. Transporting Voice over IP Network 3. Speech Coding Techniques 4. Signalling 1 – H 323 5. Signalling 2 – SIP 6. Media Gateway Control 7. Vo. IP and SS 7 8. ATM 9. QOS and Traffic management 10. Designing a Vo. IP Network © 2006 Cisco Systems, Inc. All rights reserved.

Network Components SF RTP SJ IXC CO CO - Central Office Trunk - Switch-switch connection Loop - Line from switch to phone Tandem switch - provides switch-switch interconnection IXC - interexchange carrier PBX - Private branch exchange © 2006 Cisco Systems, Inc. All rights reserved.

The PSTN: Separate Voice and Signaling Networks • SSP: Service Switching Point (Telephone Switch) • STP: Signaling Transfer Point (Router) • SCP: Service Control Point (Database, Logic) © 2006 Cisco Systems, Inc. All rights reserved. Voice SS 7 SSP STP Trunk SSP Trunk Signaling (Packet) (TDM) Trunk SSP STP SCP

Local Loop Speaker 2 wire S w i t c h Talker Echo 2 wire Listener s w i t c h 2 wire § 2 wire from phone to switch § Tip and Ring - derived from old switchboard plugs § 4 wire used at switch § Conversion performed by hybrid © 2006 Cisco Systems, Inc. All rights reserved.

Local Loop (cont. ) Problems with Analog Transmission Speaker 2 wire H y b r i d Talker Echo 2 wire Listener H y b r i d 2 wire § Several problems with analog § Attenuation - loss of signal power § Distortion - unequal loss at different frequencies § Noise - induced into line which is amplified along with signal by network components § Echo - due to 2/4 wire conversion § Physical impairments - bad lines, bridge taps, load coils © 2006 Cisco Systems, Inc. All rights reserved.

Digitizing Voice • Assumption is that human speech information is contained in the range of 300 -3400 Hz Filter & use signal below 4 k. Hz to prevent aliasing Sample and quantize signal at 8 k. Hz encoder produces 64 kbit/sec stream of data © 2006 Cisco Systems, Inc. All rights reserved.

Waveform Coders (codec) Voice ENCODER Low Pass Filter BW = Fmax Sampler 2 * Fmax Samples/Sec Quantizer n Bits/Sample 2 n Levels Binary Encoder Clock Voice De. CODER Pulse Detector © 2006 Cisco Systems, Inc. All rights reserved. Binary to Decimal Decoder Filter BW = Fmax

Non-Linear vs. Linear Encoding Companding (a-law vs -law) Output Input Non- Linear Encoding Closely Follows Human Voice Characteristics High Amplitude Signals Have More Quantization Distortion (Both a- & - Law) © 2006 Cisco Systems, Inc. All rights reserved. Linear Encoding Relatively Easy to Analyze, Synthesize, and Regenerate All Amplitudes Have Roughly Equal Quantization Distortion

Linear Predictive Coding Source Coding 10 20 ms 0001 0010 0011 0100 0101 0111 1000 1001 1010 1011 1100 1101 1110 1111 Actual Code © 2006 Cisco Systems, Inc. All rights reserved. 1001 1011 0001 0010 0011 0100 0101 0111 1000 1001 1010 1011 1100 1101 1110 1111 Predicted Code

Bandwidth Requirements Voice Band Traffic Encoding/ Compression G. 711 PCM A-Law/u-Law G. 726 ADPCM Result Bit Rate 64 kbps (DS 0) 16, 24, 32, 40 kbps G. 729 CS-ACELP 8 kbps G. 728 LD-CELP 16 kbps G. 723. 1 CELP © 2006 Cisco Systems, Inc. All rights reserved. 6. 3/5. 3 kbps Variable

Voice Quality Anything Above an MOS of 4. 0 Is “Toll” Quality Compression Method MOS Score Delay (msec) 64 K PCM (G. 711) 4. 4 0. 75 32 K ADPCM (G. 726) 4. 2 1 16 K LD-CELP (G. 728) 4. 2 3– 5 8 K CS-ACELP (G. 729) 4. 2 15 8 K CS-ACELP (G. 729 a) 3. 6 15 © 2006 Cisco Systems, Inc. All rights reserved.

Voice Activity Detection - 31 dbm B/W Saved Voice Activity (Power Level) Hang Timer No Voice Traffic Sent SID Buffer SID - 54 dbm Pink Noise Voice “Spurt” Time © 2006 Cisco Systems, Inc. All rights reserved. Silence Voice “Spurt”

Applications of Speech Coding § Telephony, PBX § Wireless/Cellular Telephony § Internet Telephony § Speech Storage (Automated call-centers) § High-Fidelity recordings/voice § Speech Analysis/Synthesis § Text-to-speech (machine generated speech) © 2006 Cisco Systems, Inc. All rights reserved.

Different Types of Signaling (when you place a call) § Supervisory - Determines state of line/trunk whether on/off-hook EM signal leads, loop open/closed § Addressing - passes digit information for call routing DTMF, DNIS § Informational - indicates call progress Busy signal, dial tone, ring back © 2006 Cisco Systems, Inc. All rights reserved.

Summary Page Local Loop FXS/ FXO Loopstart/ SF Gndstart RTP SJ IXC CO T 1/ E 1 DTMF/ MF CAS/ CCS © 2006 Cisco Systems, Inc. All rights reserved.

Voice Transport Protocols © 2006 Cisco Systems, Inc. All rights reserved.

Voice Transport Protocol Overview Encoder/ Decoder IP ATM, FR, HDLC Cisco Gateway T 1/E 1 CAS/CCS PBX PSTN © 2006 Cisco Systems, Inc. All rights reserved. Cisco Gateway

Queuing § Voice always given priority over data § Real-time queue for voice and video Data queue serviced only if nothing in Real Time queue - (Exhaustive like priority queuing) § Non-real time queue (Data) WFQ by default WFQ Disabled if Frame Relay Traffic Shaping Enabled Fancy queuing disabled if voice-encap set on interface © 2006 Cisco Systems, Inc. All rights reserved.

Voice Over IP © 2006 Cisco Systems, Inc. All rights reserved.

Protocols Used • H. 225. 0 for Connection and Status – Q. 931 ‘derived’ messages – ‘RAS’ for Endpoint-GK signaling. • H. 245 for negotiating channel usage and capabilities • Media transport – RTP/RTCP -- standard payloads (RFC 1889/1890) – ‘native’ uni/multicast support © 2006 Cisco Systems, Inc. All rights reserved.

Vo. IP Camps Conferencing Industry Netheads “IP over Everything” Circuit switch engineers “We over IP” “Convergence” ITU standards H. 323 SIP “Softswitch” BICC ISDN LAN conferencing I-multimedia WWW Call Agent SIP & H. 323 BISDN, AIN H. xxx, SIP IP “any packet” Our focus © 2006 Cisco Systems, Inc. All rights reserved.

IP SIP Phones and Adaptors 1 Are true Internet hosts • Choice of application • Choice of server 2 • IP appliances Implementations Analog phone adaptor 3 • 3 Com (3) • Columbia University Palm control • MIC World. Com (1) • Mediatrix (1) • Nortel (4) • Siemens (5) © 2006 Cisco Systems, Inc. All rights reserved. 44 5

PSTN to IP Call PBX PSTN External T 1/CAS 1 Call 9397134 Gateway Internal T 1/CAS (Ext: 7130 -7139) 2 Call 7134 Ethernet Regular phone (internal) 5 3 SIP server sipc Bob’s phone © 2006 Cisco Systems, Inc. All rights reserved. SQL database sipd 4 7134 => bob

IP to PSTN Call PSTN PBX External T 1/CAS 5 Call 5551212 Internal T 1/CAS 4 Call 85551212 Gateway (10. 0. 2. 3) 3 Ethernet 5551212 Regular phone 1 (internal, 7054) Bob calls 5551212 SIP server sipc © 2006 Cisco Systems, Inc. All rights reserved. SQL database 2 sipd Use sip: 85551212@10

End-to-End Delay Sender Receiver Network First Bit Last Bit Transmitted Received A Processin g Delay © 2006 Cisco Systems, Inc. All rights reserved. A Network Transit Delay Processin g End-to-End Delay t

Fixed Delay Components Propagation Delay Serialization Delay— Buffer to Serial Link Processing Delay § Propagation—six microseconds per kilometer § Serialization § Processing Coding/compression/decoding Packetization © 2006 Cisco Systems, Inc. All rights reserved.

Variable Delay Components Queuing Delay Dejitter Buffer § Queuing delay § Dejitter buffers § Variable packet sizes © 2006 Cisco Systems, Inc. All rights reserved.

Delay Variation—“Jitter” Sender Receiver Network B A C Sender Transmits t A D 1 B D 2 = D 1 © 2006 Cisco Systems, Inc. All rights reserved. C D 3 = D 2 Sink Receives t 85

Network Qo. S Toolkit © 2006 Cisco Systems, Inc. All rights reserved.

Logical Connections Call Leg 1 Call Leg 2 IP Cloud Call Leg 3 Call Leg 4 © 2006 Cisco Systems, Inc. All rights reserved.

Summary § The traditional three-layer hierarchical model no longer completely meets the needs of large converged networks carrying voice, video, and data. IIN aligns IT resources with business priorities. § Cisco Enterprise Architecture and SONA provide a framework for deploying converged networks. § Dealing with complex traffic mixes is a key feature of Cisco Enterprise Architecture. The Service layer of SONA addresses the performance and security requirements of converged networks. § IIN aligns IT resources with business priorities. § Cisco SONA provides an evolutionary path to IIN. © 2006 Cisco Systems, Inc. All rights reserved.