Digital Telephony Over Cable

Written for anyone with a stake in this up-and-coming field, Digital Telephony Over Cable serves as a companion guide for implementors and managers alike. It provides an accessible overview of more than a thousand pages of technical specifications with in-depth explanations of the most salient features, and offers extensive background on many of the underlying technologies that make digital telephony over cable possible. You will learn how all of these specifications come together to create a complete, functional telephony network running over a shared access medium.

Readers will find in-depth coverage of important topics such as:

• PacketCable architecture
• PacketCable devices
• Security issues, including cryptography, key management, ciphers, and X.509 certificates
• Quality of service issues, focusing on DOCSIS and DQoS
• DOCSIS and MAC specifications for cable modem communication over shared coax
• Network-based call signaling, featuring MGCP and NCS
• Distributed call signaling, featuring SIP
• Network management, covering SNMP, billing, and electronic surveillance
• Internetworking with PSTN

The book concludes with a look into the future of cable modem telephony, including possible changes to current specifications, ownership issues for the MTA, and Fiber to the Home (FTTH) technology.

Contents

1: Background.

The Residential Broadband Pipe.

Hybrid Fiber Coax Networks.

Customer Premise Equipment.

The PacketCableT Project.

The Rest of the Book

Classes of Attack..

2: Security.

Security and Conventional Telephony.

Security in Digital Networks.

Key Management.

Specific Security Mechanisms and Algorithms.

X.509 Certificates.

Other Certificates.

Ticket Granting Server Certificate.

Provisioning Server Certificate..

3: The Access Link.

The DOCSIS Specifications.

Overview of the Cable Access Network.

DOCSIS Protocol layers.

MAC Management.

Example Upstream Bandwidth Allocation.

Quality of Service (QoS).

Baseline Privacy Key Management (BPKM).

Where do we go from here?.

4: Network-Based Call Signaling.

Media Gateway Control Protocol (MGCP).

Response to RSIP.

Encoding Session Descriptions.

Security.

Bearer Channel Security.

Key Management in NCS.

Basic NCS Call Flow.

Call Features..

5: Distributed Call Signaling.

Trust.

Intelligent MTAs.

SIP Messaging.

Details of DCS Signaling.

Tearing Down a Call.

Implementing Features..

6: Quality of Service.

DQoS and RSVP.

Customer and Operator Expectations.

Gates.

Security and DqoS.

DQoS and DOCSIS.

Codecs.

Buckets and Jitter Buffers.

Flowspecs.

Flowspecs, DOCSIS, and SDP.

A Note About RTCP.

More About Gates.

Common Open Policy Service (COPS).

Protocol Operation.

Examples of COPS Messages.

Initialization of the COPS Connection.

Operation.

Gate Coordination.

Gate Coordination Message Contents.

Example Gate Coordination Message.

Use of Gate Coordination Messages.

Example Call Flow..

7: Provisioning, Back Office and Electronic Surveillance.

Simple Network Management Protocol (SNMP).

Power-On Initialization.

Event Messages.

Billing Correlation ID.

Electronic Surveillance.

CCC Message Format.

Example Call Flow.

Complication..

8: Interworking with the PSTN.

Architecture.

Signaling.

Media Control..

9: The Future.

Changes to Current Specifications.

New Specifications.

Business Issues.

Fiber to the Home (FTTH).

Putting it All Together.

Glossary.

Cyclic Redundancy Checks.

Standard Encodings.

Bearer-channel Keying Material.