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QOS
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)
VoIP
© 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 VoIP
© 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 T1 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
 T1 Carrier System: Specification for digital transmission
between telephone exchanges and sometimes directly
to customer premises. T1 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 1-8xx numbers
© 2006 Cisco Systems, Inc. All rights reserved.
Separate Voice, Video, and Data Networks
 London
Office
 San Jose
Office
PBX
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
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Cisco Enterprise Architecture
© 2006 Cisco Systems, Inc. All rights reserved.
Campus Architecture
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
Application Layer includes:
 business applications
 collaboration applications
© 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.