Part 1
R1
What is the difference between a host and an end system? List the types of end systems? Is a Web server an end system?
A host and an end system are terms that are used interchangeably meaning that a host is an end system.
The types of application programs that run are web browser programs, web server programs, and e-mail
readers and senders. So Yes a web server is an end system.
R4
List six access technologies. Classify each one as residential access, company access or mobile access
Cable Modems -> Residential Access
Digital subscriber Line -> Residential Access
Hybrid fiber-coaxial cable -> Residential Access
Ethernet Technologies -> Company Access
Wireless LAN -> Wireless Access
Bluetooth -> Wireless Access
R5
Is HFC transmission rate dedicated or shared among users? Are collisions possible in a downstream HFC channel? Why or Why
not?
HFC transmission is in fact shared among users, it has protocols that are created to limit if not reduce the
possibility of collisions.
R8
What are some physical media that Ethernet can run over?
Ethernet can use twister pair and coaxial.
R9
Dial-up modems, HFC, and DSL are all used for residential access. For each of theses technologies provide a range of transmission
rates and comment on whether the transmission rate is shared or dedicated.
Dial-up is a dedicated transmission that servers 56.6kbps and under. HFC is a shared transmission and the
rate really is dependent on the users on the line. On the other end DSL which is a dedicated transmission
has a range of 768 kbps to 1.5 mbps downstream and 128kbps to 768 kbps upstream.
R11
What advantage does a circuit-switched network have over a packet-switched network? What advantages does TDM have over
FDM in a circuit-switched network?
Circuit-switched networks have a huge overhead that is created to make sure that message is delivered. In
contrast the packet-switched networks are very quick but do not offer the guarantee. TDM allows all the
bandwidth to be used for a short period of time. This is very versatile for burst packet sending.
R12
Why is it said that packet switching employs statistical multiplexing? Contrast statistical multiplexing with the multiplexing that
takes place in TDM.
Statistical Multiplexing is the idea that link capacity is determined dynamically, rather than a
predetermined bandwidth. TDM multiplexing gives all of the bandwidth for a short period of time. This
can be problematic and cause gaps. Statistical Multiplexing fixes this issue by only allowing the time
needed to send each message be used.
Part 2
1.
Other than conventional computers, (i.e. computers such as laptops, personal computers, minicomputers and mainframes and
supercomputers), what other types of devices can appear as nodes in a computer network? (Name at least three).
Three types of conventional computers would be, cell phones, pda’s and according to the book, toasters.
2.
Explain what it means for a communication link to fall into the unguided media category, and list two types of unguided media
links.
In order to be considered unguided media you first cannot be using a solid medium. Two types of
unguided media would be satellite radio waves and terrestrial radio waves.
3.
List the three different types of guided media that are commonly employed as to implement links in computer
networks.
1) Coax wire
2) Optical fiber
3) Twister pair
4.
Define the notions of simplex, half-duplex , and full-duplex transmission.
A simplex transmission is a connection between one sender and one receiver where there is a pair of
wires where the sender has a plus and minus terminals in which data can be transmitted from the sender
to the receiver. In comparison a half duplex allows the sender and receiver to both send and receive data
but only one node can send at a time. Finally the Full-duplex transmission which has two pairs of wires
such that both sides can send and receive messages. The problem with this is that these wires suffer from
Emi so to fix that it would be suggested to use twisted wires instead.
5.
Twisted pairs are used a lot in both data and voice communications
1)
Why does it require a pair of wires to carry a signal from a sender to a receiver?
You use two wires to complete the circuit in order for the current to flow from the sender terminal to
the receiver. Based on a couple factors the receiver can then decode the binary into 1’s and 0’s. The
sender sends information through the negative terminal.
2)
Why are the two wires that carry the signal twister together?
The twisting of wires is done this way to prevent / cut down on the amount of electro-magnetic
interference.
3)
If you pull the telephone wire out of a telephone handset and examine the connect, you will see 4 contacts, suggesting that
the cable to the telephone consists of 4 wires, that is, two twisted pairs. Why are there two twisted pairs instead of one?
In order to communicate bilaterally, the ability for the headset to sender and receive messages you
will need two twisted pairs.
4)
The telephone wiring in residential homes is made up of four pairs of twisted pair, even though a telephone only uses two
of those pairs. What are the two extra twister pairs for?
This allows the residential area to install another phone line without having to rip up the current
line.
6.
What is the difference between RJ-11 and RJ-45 cable?
The difference between these two cables is the amount of twist over a set length. The RJ-45 has more
twists per length then the RJ-11.
7.
Expand the following network acronyms, and state briefly how the concepts denoted by the acronyms differ from each other?
1) LAN – Local Area Network. This is used in residential homes and on school campus to provide
2)
8.
internet/networking services.
WAN – Wide Area Network. This network ranges over a large region, state, country, continent or even
planet.
PAN – Personal Area Network. This network ranges a very short distance.
3)
Explain what Bluetooth is?
Bluetooth is a wireless PAN.
9.
Explain the concept of a network topology, and list four topologies more frequently used in a computer network.
A topology when in context to networking is a pattern of interconnecting nodes. The four types that
popularly used are ring, star, mesh, and bus.
10. Explain what is meant when we say that a link is point to point
Point to point means that messages are sent from point to point until it reaches the destination. In
contrast to broadcast, which is sent to every node in the network.
11. How does a computer network differ from an internetwork?
A computer network is used t connect single computers to each other. In comparison an internetwork
connects various computer networks to one another.
12. What do we mean when we say that a machine is multi-homed?
A machine is considered to be multi-homed if it is a member of more than one network