This detailed study of the H.323 architecture consists of lecture and hands-on tasks, enabling you to understand what H.323 is and how it works. The lessons in this course are clear, very technical, and always presented with hands-on examples. In fact, the course is at least 60% hands on, so you can investigate each lesson and confirm your understanding of RAS, H.225, H.245, and RTP.

What You'll Learn

• Purpose of Real-Time Transport Protocol (RTP) and RTP Control Protocol (RTCP)
• Different components of H.323
• Register, Admission, and Status (RAS) and other H.323 protocols
• Relationship between H.323 and H.248
• Overview of H.245
• H.323 versions 2, 3, 4, and 5

Who Needs to Attend

Technical people who support H.323-based systems; anyone who wants a vendor-neutral, technical understanding of how H.323 systems work.

Prerequisites

• Voice over IP Foundations

Follow-On Courses

• VoIP Protocol Essentials: SIP
• The IP Multimedia Subsystem (IMS)
• MEGACO (H.248) and the IMS

Course Outline

1. Real-Time Transport Protocol (RTP)

• Payload Types
• RTP Timestamps
• Silence Suppression
• Supporting Real-Time Traffic
• The First Voice Packet
• The Second Voice Packet
• The Third Voice Packet
• A Jitter Buffer Operation
• The Adaptive Jitter Buffer Example
• RTP Sequence #
• Synchronization Source
• Contributing Source (CSRC)
• DTMF (RFC 2833)
• Telephony Tones & Signals (RFC 2833)
• RTP Header Compression (RFC 2508)
• RTP Packet - Find RTP Fields using Ethereal (now called Wireshark)
• RTP Control Protocol (RTCP)
  • Source Descriptions (SDES)
  • Sender Reports (SENDER)
  • Receiver Reports (RECEIVER)
  • RTCP Calculates Round Trip
  • RTCP BYE Report

2. ASN.1

• Sending Data, not the Format
• ASN.1 Basics
• ASN.1 Modules
• Basic Encoding Rules (BER)
• Packed Encoding Rules (PER)
• ASN.1 Exercise
  • Decode an H.245 terminalCapabilitySet Message
  • How to Reference H.245 Annex A
  • OID

3. H.323 Architecture

• H.323 Stack
• H.323 Components
  • Terminal
  • MCU
  • Gateway
  • Gatekeeper
  • Border Element
• GK Zone
• Relationship between H.323 and H.248
• H.323 Administrative Domain
• RAS vs. Annex G

4. RAS

• RAS and other H.323 Protocols
• RAS Request/Response
• RAS Message Set
• RAS at Layer 4
• RAS at Layer 3
• Close Look at Popular RAS Messages
  • GRQ - GCF/GRJ Exchange
  • GK Discovery
  • RRQ - RCF/RRJ Exchange
  • LW RRQs
  • ARQ - ACF/ARJ Exchange
  • LRQ - LCF/LRJ
  • BRQ - BRF/BRJ Exchange
  • DRQ - DCF/DRJ
  • IRQ - IRR
  • RAAI - RAC
  • SCI - SCR

5. H.225.0

• Usage of Q.931
• Q.932 Messages Supported/Forbidden
• Q.922 Messages
• Direct Endpoint Signaling
• GK Routing
• Direct Endpoint Signaling - Only called endpoint registered
• Call Example - Both endpoints registered across multiple zones
• Call Example - Using multiple zones and LRQ/LCF
• RSVP Sync (Cisco)

6. H.245

• H.245 Overview
• H.245 Tunneling
• Call Setup Example - Using RAS, Call signaling channel, and H.245
• Terminal Capability Exchange
• Master/Slave Determination
• Logical Channel Signaling
• Overlap Dialing
• The Capability Table
• Simultaneous Capabilities
• Capability Descriptors
• The Role of the Master

7. Fast Connect Procedure

• SETUP
• CALL PROCEEDING
• PROGRESS
• fastStart Procedure

8. T.38 and H.323

• The T.38 Process
• Reading a T.38 Decode

9. H.323 Versions

• Version 2
• Version 3
• Version 4
• Version 5

Labs

1. H.323 Endpoint Configuration

2. H.323 GK Configuration

3. GK Registration

4. CODEC Negotiation

5. GK-to-GK Routing

6. Using Ethereal (now called Wireshark) Capture and Decode (Live Labs and Capture)

• RAS
• H.225
• H.245
• GK Registration
• Slow Start
• GK Routed
• Fast Connect
• Direct Endpoint Signaling
• H.245 Tunneling
• Call Setup
• Busy Call
• Abandoned Call
• Codec Mismatch
• Vacant Number
• GK ID Mismatch
• NAT Traversal
• Silence Suppression
• RFC 2833
• PROGRESS - Interoperability into CAS