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47
s2
iu
en
dyg
tu
, Data and Computer Communications
10th Edition
tu
William Stallings
10TH EDITION
d
TABLE OF CONTENTS
yg
PART ONE — OVERVIEW
Chapter 1 Data Communications, Data Networks, and the Internet
Chapter 2 Protocol Architecture, TCP/IP, and Internet-Based Applications
en
PART TWO — DATA COMMUNICATIONS
Chapter 3 Data Transmission
Chapter 4 Transmission Media
iu
Chapter 5 Signal Encoding Techniques
Chapter 6 Digital Data Communication Techniques
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Chapter 7 Data Link Control
Chapter 8 Multiplexing
Chapter 9 Spread Spectrum
47
PART THREE — COMMUNICATION NETWORKS
Chapter 10 Circuit Switching and Packet Switching
Chapter 11 Asynchronous Transfer Mode
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PART FOUR — WIRELESS COMMUNICATIONS
Chapter 12 Wireless Transmission
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Chapter 13 Wireless Networks
Chapter 14 Cellular Wireless Networks
Chapter 15 Bluetooth and IEEE 802.15
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Chapter 16 Wireless LANs
PART FIVE — LOCAL AREA NETWORKS
Chapter 17 Local Area Network Overview
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Chapter 18 Ethernet
, Chapter 19 Token Ring LANs and FDDI
PART SIX — INTERNET PROTOCOLS
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Chapter 20 Network Layer Protocols: IP, IPv6, ICMP, and ICMPv6
Chapter 21 Transport Layer Protocols: UDP and TCP
Chapter 22 Network Security
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Chapter 23 Internet Applications: HTTP, FTP, SMTP, DNS, and VoIP
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PART SEVEN — WIDE AREA NETWORKS
Chapter 24 Wide Area Protocols and Services
Chapter 25 xDSL
en
APPENDICES
Appendix A Fourier Analysis
Appendix B Protocols and Standards
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Appendix C Sockets: A Programmer's Introduction
Appendix D Queue Modeling Concepts
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Appendix E Error Detection: Parity Check and CRC
© 2013 Pearson Education, Inc. All rights reserved.
47
??
??
??
??
, 2.4 No. There is no way to be assured that the last message gets through,
except by acknowledging it. Thus, either the acknowledgment process
continues forever, or one army has to send the last message and then
act with uncertainty.
tu
2.5 A case could be made either way. First, look at the functions
performed at the network layer to deal with the communications
network (hiding the details from the upper layers). The network layer is
d
responsible for routing data through the network, but with a broadcast
network, routing is not needed. Other functions, such as sequencing,
flow control, error control between end systems, can be accomplished at
yg
layer 2, because the link layer will be a protocol directly between the
two end systems, with no intervening switches. So it would seem that a
network layer is not needed. Second, consider the network layer from
the point of view of the upper layer using it. The upper layer sees itself
en
attached to an access point into a network supporting communication
with multiple devices. The layer for assuring that data sent across a
network is delivered to one of a number of other end systems is the
network layer. This argues for inclusion of a network layer.
In fact, the OSI layer 2 is split into two sublayers. The lower sublayer
iu
is concerned with medium access control (MAC), assuring that only one
end system at a time transmits; the MAC sublayer is also responsible for
addressing other end systems across the LAN. The upper sublayer is
s2
called Logical Link Control (LLC). LLC performs traditional link control
functions. With the MAC/LLC combination, no network layer is needed
(but an internet layer may be needed).
47
2.6 a. No. This would violate the principle of separation of layers. To layer
(N – 1), the N-level PDU is simply data. The (N – 1) entity does not
know about the internal format of the N-level PDU. It breaks that
PDU into fragments and reassembles them in the proper order.
b. Each N-level PDU must retain its own header, for the same reason
??
given in (a).
2.7 Data plus transport header plus internet header equals 1820 bits. This
data is delivered in a sequence of packets, each of which contains 24
??
bits of network header and up to 776 bits of higher-layer headers
and/or data. Three network packets are needed. Total bits delivered =
1820 + 3 × 24 = 1892 bits.
??
2.8 UDP provides the source and destination port addresses and a checksum
that covers the data field. These functions would not normally be
performed by protocols above the transport layer. Applications can't
provide port addresses (they aren't really addresses). Port-ids have to
??
be unambiguous between the application and the layer (or OS). If they
were provided by the application then the same port-id could be
-7-
??
??
??
47
s2
iu
en
dyg
tu
, Data and Computer Communications
10th Edition
tu
William Stallings
10TH EDITION
d
TABLE OF CONTENTS
yg
PART ONE — OVERVIEW
Chapter 1 Data Communications, Data Networks, and the Internet
Chapter 2 Protocol Architecture, TCP/IP, and Internet-Based Applications
en
PART TWO — DATA COMMUNICATIONS
Chapter 3 Data Transmission
Chapter 4 Transmission Media
iu
Chapter 5 Signal Encoding Techniques
Chapter 6 Digital Data Communication Techniques
s2
Chapter 7 Data Link Control
Chapter 8 Multiplexing
Chapter 9 Spread Spectrum
47
PART THREE — COMMUNICATION NETWORKS
Chapter 10 Circuit Switching and Packet Switching
Chapter 11 Asynchronous Transfer Mode
??
PART FOUR — WIRELESS COMMUNICATIONS
Chapter 12 Wireless Transmission
??
Chapter 13 Wireless Networks
Chapter 14 Cellular Wireless Networks
Chapter 15 Bluetooth and IEEE 802.15
??
Chapter 16 Wireless LANs
PART FIVE — LOCAL AREA NETWORKS
Chapter 17 Local Area Network Overview
??
Chapter 18 Ethernet
, Chapter 19 Token Ring LANs and FDDI
PART SIX — INTERNET PROTOCOLS
tu
Chapter 20 Network Layer Protocols: IP, IPv6, ICMP, and ICMPv6
Chapter 21 Transport Layer Protocols: UDP and TCP
Chapter 22 Network Security
d
Chapter 23 Internet Applications: HTTP, FTP, SMTP, DNS, and VoIP
yg
PART SEVEN — WIDE AREA NETWORKS
Chapter 24 Wide Area Protocols and Services
Chapter 25 xDSL
en
APPENDICES
Appendix A Fourier Analysis
Appendix B Protocols and Standards
iu
Appendix C Sockets: A Programmer's Introduction
Appendix D Queue Modeling Concepts
s2
Appendix E Error Detection: Parity Check and CRC
© 2013 Pearson Education, Inc. All rights reserved.
47
??
??
??
??
, 2.4 No. There is no way to be assured that the last message gets through,
except by acknowledging it. Thus, either the acknowledgment process
continues forever, or one army has to send the last message and then
act with uncertainty.
tu
2.5 A case could be made either way. First, look at the functions
performed at the network layer to deal with the communications
network (hiding the details from the upper layers). The network layer is
d
responsible for routing data through the network, but with a broadcast
network, routing is not needed. Other functions, such as sequencing,
flow control, error control between end systems, can be accomplished at
yg
layer 2, because the link layer will be a protocol directly between the
two end systems, with no intervening switches. So it would seem that a
network layer is not needed. Second, consider the network layer from
the point of view of the upper layer using it. The upper layer sees itself
en
attached to an access point into a network supporting communication
with multiple devices. The layer for assuring that data sent across a
network is delivered to one of a number of other end systems is the
network layer. This argues for inclusion of a network layer.
In fact, the OSI layer 2 is split into two sublayers. The lower sublayer
iu
is concerned with medium access control (MAC), assuring that only one
end system at a time transmits; the MAC sublayer is also responsible for
addressing other end systems across the LAN. The upper sublayer is
s2
called Logical Link Control (LLC). LLC performs traditional link control
functions. With the MAC/LLC combination, no network layer is needed
(but an internet layer may be needed).
47
2.6 a. No. This would violate the principle of separation of layers. To layer
(N – 1), the N-level PDU is simply data. The (N – 1) entity does not
know about the internal format of the N-level PDU. It breaks that
PDU into fragments and reassembles them in the proper order.
b. Each N-level PDU must retain its own header, for the same reason
??
given in (a).
2.7 Data plus transport header plus internet header equals 1820 bits. This
data is delivered in a sequence of packets, each of which contains 24
??
bits of network header and up to 776 bits of higher-layer headers
and/or data. Three network packets are needed. Total bits delivered =
1820 + 3 × 24 = 1892 bits.
??
2.8 UDP provides the source and destination port addresses and a checksum
that covers the data field. These functions would not normally be
performed by protocols above the transport layer. Applications can't
provide port addresses (they aren't really addresses). Port-ids have to
??
be unambiguous between the application and the layer (or OS). If they
were provided by the application then the same port-id could be
-7-
