1. Protocols and the TCP/IP Suite Overview and Discussion
Voice-over-IP
Overview and Discussion
Chapter 2

2. Protocols and the TCP/IP Suite
ITU VoIP Network Model
Gatekeeper
PSTN
Internet
Gateway
Zone
Terminal
Chapter 2

3. Protocols and the TCP/IP Suite
ITU H.323 Architecture
Control Application
Speech
G.7xx
compression
Q.931
Call
Signaling
H.245
Call
Control
H.225
RAS
RTCP
RTP
UDP
TCP IP
Data Link Protocol
Physical Layer Protocol
Chapter 2

4. Protocols and the TCP/IP Suite
ITU H.323 Logical Channels
Call signaling channel (Q.931)
Call control channel (H.245)
Forward data channel (RTP) >>>>
<<<< Reverse data channel (RTP)
Data control channel (RTCP)
Caller
Callee
Chapter 2

5. Protocols and the TCP/IP Suite
IETF Architecture
Speech
Control Application
Compression
Gateway
Location
Protocol
Session Initiation
Protocol
RTCP
RTP
SDP
UDP
TCP/UDP IP
Data Link Protocol
Physical Layer Protocol
Chapter 2

6. H.323 Call Flow

7. H.323 Call Flow
1 Endpoint A sends a setup message to Endpoint B on TCP Port 1720.
2 Endpoint B replies to the setup message with an alerting message and a port number
to start H.245 negotiation.
3 H.245 negotiation includes codec types (G.729 and G.723.1), port numbers for the
RTP streams, and notification of other capabilities the endpoints have.
4 Logical channels for the UDP stream are then negotiated, opened, and acknowledged.
5 Voice is then carried over RTP streams.
6 Real Time Transport Control Protocol is used to transmit information about the RTP
stream to both endpoints.

8. Virtual Switch Controller

9. Protocols and the TCP/IP Suite
                                                                                          
Protocols and the TCP/IP Suite
Typical SIP
Control Flow
Chapter 2

10. VoIP Class Discussion Topics
Protocols and the TCP/IP Suite
VoIP Class Discussion Topics
VoIP <-> PSTN Comparison (Varshey, et. al.)
differences
coexistence/evolution
Performance Issues in Practice (James, et.al.)
packet loss
speech coding/compression
silence suppression and echo
delay and jitter
Reliability Issues (Johnson, et. al.)
Chapter 2