application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice. Legal practice is not just about applying laws; it is also
about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability to reason ethically and consider the consequences of legal decisions
SOLUTION MANUAL
OF
COMMUNICATION NETWORKS
BY
ALBERTO LEON GARCIA
& INDRA WIDJAJA
Chapter 1-10 with Verified
business trends. Case studies from leading businesses can be helpful, as they illustrate how business concepts are applied in real-world
scenarios. Group discussions and practicing sample case studies can aid in refining analytical skills.________________________________________2.
,Solutions to Chapter 1
1a. Describe the step-by-step procedure that is involved from the time you deposit a letter in a mailbox to the time
the letter is delivered to its destination. What role do names, addresses and mail codes (such as ZIP codes or postal
codes) play? How might the letter be routed to its destination? To what extent can the process be automated?
business trends. Case studies from leading businesses can be helpful, as they illustrate how business concepts are applied in real-world scenarios. Group discussions and
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal
precedents, and suggest possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice.
Legal practice is not just about applying laws; it is also about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability
to reason ethically and consider the consequences of legal decisions
Solution:
The steps involved in mailing a letter are:
1. The letter is deposited in mailbox.
2. The letter is picked up by postal employee and placed in sack.
3. The letter is taken to a sorting station, where it is sorted according to destination, as
determined by the mail code and grouped with other letters with the same destination mail
code. (If there is no mail code, then it is determined by the largest geographical unit, for
example, country (if specified), otherwise state (if specified), otherwise city (if specified).)
4. The letter is shipped to the post office that handles the mail for the specific mail code (or
country or city).
5. The letter is then sorted by street address.
6. The letter is picked up at the post office by the postal worker responsible for delivering to the
specified address.
7. The letter is delivered according to the number and street.
The name is not really used, unless the street address is missing or incorrect. The name is at the
destination to determine who the letter belongs to. (Unless of course the letter is being sent to a
small town, where most inhabitants are known to the postal worker.)
The mail delivery process can be automated by using optical recognition on the mail code. The
letter can then be sorted and routed to the destination postal station, and even to the destination
neighborhood, depending on the amount of geographical detail built into the mail code.
1b. Repeat part (a) for an e-mail message. At this point, you may have to conjecture different approaches about
what goes on inside the computer network.
Solution:
The steps involved in e-mailing a message are:
1. The message is sent electronically by clicking 'Send'. (In Chapter 2 we see that the Simple
Mail Transfer Protocol (SMTP) is used to do this.)
2. The mail provider of the sender sends a request to a name server for the network address of
the mail provider of the recipient. The mail provider is determined by the information following
the @ symbol.
3. If the mail provider finds the network address of the recipient's mail provider, then it sends the
message to that address.
, Leon-Garcia/Widjaja 1
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice. Legal practice is not just about applying laws; it is
also about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability to reason ethically and consider the consequences of legal decisions
4. Upon receipt of the message the mail provider either informs the recipient automatically that
there is mail or waits until mail is requested by the recipient, depending on how the mail
service is set up. The recipient is determined by the information before the @ symbol. business
trends. Case studies from leading businesses can be helpful, as they illustrate how business concepts are applied in real-world scenarios. Group discussions and
practicing sample case studies can aid in refining analytical skills.________________________________________2.
1c. Are the procedures in parts (a) and (b) connection-oriented or connectionless?
Solution:
The transfer service of letters in a postal system is connectionless. Users do not set up
connections prior to the transfer of each letter. (Note however that the postal system may have
regularly scheduled shipments of bundles of mail from city to city, because the volume of mail
between cities is predictable. These regular shipments can be viewed as pre-arranged
"connections.")
E-mail transfer is also a connectionless service in that the user does not set up end-to-end
connections to send a message. We will see in Chapter 2, however, that e-mail protocols use
connection-oriented procedures to exchange messages.
NOTE: For parts (a) and (b) other step-by-step procedures are possible.
2a. Describe what step-by-step procedure might be involved inside the network in making a telephone connection.
Solution:
1. The telephone number specifies an "address" where the receiver is located. In the North
American telephone numbering system the first three digits are the area code which specifies
the main geographical region of the receiver; the next three digits specify a particular
telephone office in the North American network. The final four digits identify the particular
location of the receiver.
2. When a telephone number is dialed equipment at the other end of the telephone line uses the
sequence of dialed numbers to determine a route across the telephone network from the call-
originating phone to the destination phone. A circuit is established between the originating
and destination phone along the identified route.
3. A ringing tone is then applied at the destination to indicate that there is an incoming call. If the
destination party (a person, an answering machine, or some other device) is ready to answer,
the call is completed through the lifting of the phone set or some equivalent action. The
setting up of telephone calls is discussed in Chapter 4.
2b. Now consider a personal communication service that provides a user with a personal telephone number. When
the number is dialed, the network establishes a connection to wherever the user is located at the given time. What
functions must the network now perform in order to implement this service?
Solution:
1. The key difference here is that the personal telephone number is not tied to a specific
location. Instead the personal number is associated with one or more pieces of equipment,
for example, a cell phone, that can request service from various points in the network. This
necessitates the translation of the personal telephone number to a number that corresponds
to a specific location in the network at a given time.
2. When the telephone number is dialed, a message requesting a connection setup is sent to
, the "home" location of the personal number.
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice. Legal practice is not just about applying laws; it is
also about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability to reason ethically and consider the consequences of legal decisions
3. The home location must somehow be able to redirect the connection setup process to the
current location of the user. For example, the user may register one or more forwarding
"addresses" to which calls are to be redirected. The signaling system is used to locate the
user. In cellular telephony, for example, requests for connections to a given mobile
telephone are broadcast over specific signaling channels.
4. Once the location of the destination is identified a connection is established. business trends. Case studies from leading businesses
can be helpful, as they illustrate how business concepts are applied in real-world scenarios. Group discussions and practicing sample case studies can aid in refining analytical
skills.________________________________________2.
3. Explain how the telephone network might modify the way calls are handled to provide the following services:
Solutions follow questions:
a. Call Display: the number and/or name of the calling party is listed on a screen before the call is answered.
Along with the request for connection setup, the system sends identifying information regarding the
originator's phone.
b. Call Waiting: a special sound is heard when the called party is on the line and another user is trying to
reach the called party.
When a second caller tries to access a busy line, the system applies an audible sound, for example, a
"beep" or a tone, to the voice signal that is being sent to the called party. The tone alerts the called
party that there is an incoming call and provides the choice of answering the second call without
disconnecting the first call.
c. Call Answer: if the called party is busy or after the phone rings a prescribed number of times, the network
gives the caller the option of leaving a voice message.
If the call is not answered after so many rings, the system establishes a connection to another
number (that is, forwards the call) that is associated with the answering system. The call is then
automatically answered by an answering system.
d. Three-Way-Calling: allows a user to talk with two other people at the same time.
After the establishment of a call between two parties, the caller can then indicate to the telephone
system that he or she wants to call a third party. Without disconnecting the first pair, the system sets
up a connection to the second called party, and once established, transmits both conversations to all
parties simultaneously. Special equipment is required to combine and distribute the voice signals of
the three parties.
4a. Suppose that the letter in problem 1 is sent by fax. Is this mode of communications connectionless or
connection-oriented? Real-time or non-real time?
Solution:
In order to send the letter by fax, a telephone connection must first be established. Therefore the
mode of communications is connection-oriented. The transfer of information across the network
occurs in real-time.
4b. Repeat part (a) if a voice mail message is left at a given telephone.
Solution:
Again, the process of leaving a voice mail message is connection-oriented, since there must be an
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice. Legal practice is not just about applying laws; it is also
about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability to reason ethically and consider the consequences of legal decisions
SOLUTION MANUAL
OF
COMMUNICATION NETWORKS
BY
ALBERTO LEON GARCIA
& INDRA WIDJAJA
Chapter 1-10 with Verified
business trends. Case studies from leading businesses can be helpful, as they illustrate how business concepts are applied in real-world
scenarios. Group discussions and practicing sample case studies can aid in refining analytical skills.________________________________________2.
,Solutions to Chapter 1
1a. Describe the step-by-step procedure that is involved from the time you deposit a letter in a mailbox to the time
the letter is delivered to its destination. What role do names, addresses and mail codes (such as ZIP codes or postal
codes) play? How might the letter be routed to its destination? To what extent can the process be automated?
business trends. Case studies from leading businesses can be helpful, as they illustrate how business concepts are applied in real-world scenarios. Group discussions and
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal
precedents, and suggest possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice.
Legal practice is not just about applying laws; it is also about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability
to reason ethically and consider the consequences of legal decisions
Solution:
The steps involved in mailing a letter are:
1. The letter is deposited in mailbox.
2. The letter is picked up by postal employee and placed in sack.
3. The letter is taken to a sorting station, where it is sorted according to destination, as
determined by the mail code and grouped with other letters with the same destination mail
code. (If there is no mail code, then it is determined by the largest geographical unit, for
example, country (if specified), otherwise state (if specified), otherwise city (if specified).)
4. The letter is shipped to the post office that handles the mail for the specific mail code (or
country or city).
5. The letter is then sorted by street address.
6. The letter is picked up at the post office by the postal worker responsible for delivering to the
specified address.
7. The letter is delivered according to the number and street.
The name is not really used, unless the street address is missing or incorrect. The name is at the
destination to determine who the letter belongs to. (Unless of course the letter is being sent to a
small town, where most inhabitants are known to the postal worker.)
The mail delivery process can be automated by using optical recognition on the mail code. The
letter can then be sorted and routed to the destination postal station, and even to the destination
neighborhood, depending on the amount of geographical detail built into the mail code.
1b. Repeat part (a) for an e-mail message. At this point, you may have to conjecture different approaches about
what goes on inside the computer network.
Solution:
The steps involved in e-mailing a message are:
1. The message is sent electronically by clicking 'Send'. (In Chapter 2 we see that the Simple
Mail Transfer Protocol (SMTP) is used to do this.)
2. The mail provider of the sender sends a request to a name server for the network address of
the mail provider of the recipient. The mail provider is determined by the information following
the @ symbol.
3. If the mail provider finds the network address of the recipient's mail provider, then it sends the
message to that address.
, Leon-Garcia/Widjaja 1
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice. Legal practice is not just about applying laws; it is
also about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability to reason ethically and consider the consequences of legal decisions
4. Upon receipt of the message the mail provider either informs the recipient automatically that
there is mail or waits until mail is requested by the recipient, depending on how the mail
service is set up. The recipient is determined by the information before the @ symbol. business
trends. Case studies from leading businesses can be helpful, as they illustrate how business concepts are applied in real-world scenarios. Group discussions and
practicing sample case studies can aid in refining analytical skills.________________________________________2.
1c. Are the procedures in parts (a) and (b) connection-oriented or connectionless?
Solution:
The transfer service of letters in a postal system is connectionless. Users do not set up
connections prior to the transfer of each letter. (Note however that the postal system may have
regularly scheduled shipments of bundles of mail from city to city, because the volume of mail
between cities is predictable. These regular shipments can be viewed as pre-arranged
"connections.")
E-mail transfer is also a connectionless service in that the user does not set up end-to-end
connections to send a message. We will see in Chapter 2, however, that e-mail protocols use
connection-oriented procedures to exchange messages.
NOTE: For parts (a) and (b) other step-by-step procedures are possible.
2a. Describe what step-by-step procedure might be involved inside the network in making a telephone connection.
Solution:
1. The telephone number specifies an "address" where the receiver is located. In the North
American telephone numbering system the first three digits are the area code which specifies
the main geographical region of the receiver; the next three digits specify a particular
telephone office in the North American network. The final four digits identify the particular
location of the receiver.
2. When a telephone number is dialed equipment at the other end of the telephone line uses the
sequence of dialed numbers to determine a route across the telephone network from the call-
originating phone to the destination phone. A circuit is established between the originating
and destination phone along the identified route.
3. A ringing tone is then applied at the destination to indicate that there is an incoming call. If the
destination party (a person, an answering machine, or some other device) is ready to answer,
the call is completed through the lifting of the phone set or some equivalent action. The
setting up of telephone calls is discussed in Chapter 4.
2b. Now consider a personal communication service that provides a user with a personal telephone number. When
the number is dialed, the network establishes a connection to wherever the user is located at the given time. What
functions must the network now perform in order to implement this service?
Solution:
1. The key difference here is that the personal telephone number is not tied to a specific
location. Instead the personal number is associated with one or more pieces of equipment,
for example, a cell phone, that can request service from various points in the network. This
necessitates the translation of the personal telephone number to a number that corresponds
to a specific location in the network at a given time.
2. When the telephone number is dialed, a message requesting a connection setup is sent to
, the "home" location of the personal number.
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
possible solutions to legal issues.Moreover, law exams prepare students for the ethical dilemmas and moral questions they will face in practice. Legal practice is not just about applying laws; it is
also about understanding the broader social and ethical implications of decisions. Law exams often test a student's ability to reason ethically and consider the consequences of legal decisions
3. The home location must somehow be able to redirect the connection setup process to the
current location of the user. For example, the user may register one or more forwarding
"addresses" to which calls are to be redirected. The signaling system is used to locate the
user. In cellular telephony, for example, requests for connections to a given mobile
telephone are broadcast over specific signaling channels.
4. Once the location of the destination is identified a connection is established. business trends. Case studies from leading businesses
can be helpful, as they illustrate how business concepts are applied in real-world scenarios. Group discussions and practicing sample case studies can aid in refining analytical
skills.________________________________________2.
3. Explain how the telephone network might modify the way calls are handled to provide the following services:
Solutions follow questions:
a. Call Display: the number and/or name of the calling party is listed on a screen before the call is answered.
Along with the request for connection setup, the system sends identifying information regarding the
originator's phone.
b. Call Waiting: a special sound is heard when the called party is on the line and another user is trying to
reach the called party.
When a second caller tries to access a busy line, the system applies an audible sound, for example, a
"beep" or a tone, to the voice signal that is being sent to the called party. The tone alerts the called
party that there is an incoming call and provides the choice of answering the second call without
disconnecting the first call.
c. Call Answer: if the called party is busy or after the phone rings a prescribed number of times, the network
gives the caller the option of leaving a voice message.
If the call is not answered after so many rings, the system establishes a connection to another
number (that is, forwards the call) that is associated with the answering system. The call is then
automatically answered by an answering system.
d. Three-Way-Calling: allows a user to talk with two other people at the same time.
After the establishment of a call between two parties, the caller can then indicate to the telephone
system that he or she wants to call a third party. Without disconnecting the first pair, the system sets
up a connection to the second called party, and once established, transmits both conversations to all
parties simultaneously. Special equipment is required to combine and distribute the voice signals of
the three parties.
4a. Suppose that the letter in problem 1 is sent by fax. Is this mode of communications connectionless or
connection-oriented? Real-time or non-real time?
Solution:
In order to send the letter by fax, a telephone connection must first be established. Therefore the
mode of communications is connection-oriented. The transfer of information across the network
occurs in real-time.
4b. Repeat part (a) if a voice mail message is left at a given telephone.
Solution:
Again, the process of leaving a voice mail message is connection-oriented, since there must be an
application, rather than simply recalling legal rules. Additionally, many law exams involve essays where students must present well-argued opinions, critically evaluate legal precedents, and suggest
