Keylii Hinton
Computer Network I
2/20/2024
6) List the available residential access technologies in your city. For each type of access,
provide the advertised downstream rate, upstream rate, and monthly price.
1. Fiber Optic:
Downstream Rate: Up to 1 Gbps or higher
Upstream Rate: Up to 1 Gbps or higher
Monthly Price: Varies depending on the provider and the chosen package, but can range from
$50 to $150 or more.
2. Cable Internet:
Downstream Rate: Up to 500 Mbps
Upstream Rate: Up to 50 Mbps
Monthly Price: Typically ranges from $30 to $100 or more, depending on the provider and
package.
3. DSL (Digital Subscriber Line):
Downstream Rate: Up to 100 Mbps (for newer VDSL technology)
Upstream Rate: Up to 10 Mbps
Monthly Price: Usually ranges from $20 to $60, depending on the provider and package.
4. Satellite Internet:
Downstream Rate: Up to 100 Mbps (depending on the provider and plan)
Upstream Rate: Up to 10 Mbps (depending on the provider and plan)
Monthly Price: Can range from $50 to $150 or more, with additional equipment and installation
costs sometimes included.
5. Fixed Wireless:
Downstream Rate: Up to 100 Mbps
Upstream Rate: Up to 50 Mbps
Monthly Price: Varies based on the provider and location, but typically ranges from $30 to $100
per month.
6. Mobile Broadband (4G/5G):
Downstream Rate: Up to 1 Gbps (5G) or lower (4G)
Upstream Rate: Up to 100 Mbps (5G) or lower (4G)
Monthly Price: Prices vary widely depending on data caps, speed tiers, and the provider, ranging
from $20 to $100 or more per month.
9) Dial-up modems, HFC, DSL and FTTH are all used for residential access. For each of
these access technologies, provide a range of transmission rates and comment on whether
the transmission rate is shared or dedicated.
1.
Dial-up Modems:
Transmission Rates can vary but typically ranges from 28.8 kbps to 56 kbps. The
transmission rate is dedicated, meaning the entire bandwidth is allocated to a single user during
their session.
2.
Hybrid Fiber-Coaxial (HFC):
The transmissions rates can vary widely depending on the network congestion. This can
range from a few Mbps to hundreds of Mbps. The transmission rate is shared among multiple
users in the same neighborhood or local area. Bandwidth is divided dynamically based on
demand.
3. Digital Subscriber Line (DSL):
Based on the distance from the telephone exchange, line quality, and DSL technology. Typical
rates range from 256 kbps to 100 Mbps. The transmission rate is dedicated to each subscriber's
line.
4. Fiber to the Home (FTTH):
Typically offers symmetrical speeds ranging from 100 Mbps to 1 Gbps or even higher.
The transmission rate is dedicated to each subscriber's fiber connection. Fiber optic cables
provide high bandwidth, and each subscriber typically receives the full speed they subscribe to
without sharing with others in the same neighborhood.
10) Describe the most popular wireless Internet access technologies today. Compare and
contrast them.
Wireless LANs - WLAN is a type of local acres network that uses wireless communication to
connect devices within a limited area such as a home or office. It uses access points or routers to
transmit and receive daa wirelessly.
Wifi - This is a wireless technology that allows for electronic devices to connect to a LAN
wirelessly. Similar to a WLAN wifi enables devices to exchange data and access the internet
within a limited range of an access point or router.Wi-Fi networks are a type of WLAN but not
all WLANs are Wi-Fi.
Bluetooth - This is a wireless technology that is the standard for exchanging data over short
distances most of the time between two personal devices. Unlike most other wireless
technologies bluetooth doesnt infact connect you to the internet.
5G/4G/LTE - This is cellular network technology that is used for wireless broadband
communication for mobile devices and data terminals, designed to increase data capacity and
speed on cellular networks. 5G being the most recent and fastest method of communication
while 4G and LTE still has good speed and such but is just the older slower version.
Satellites - Satellites are used for many things. For instance, communication satellites are
particularly relevant to wireless communication, as they relay signals between ground stations
and facilitate global communication networks, including satellite internet services and satellite
television. Not to mention they are responsible for such accurate GPS’s
13) Suppose users share a 2 Mbps link. Also suppose each user transmits continuously at 1
Mbps when transmitting, but each user transmits only 20 percent of the time.
a. When circuit switching is used, how many users can be supported?
When circut switching is used only two people can be supported for an end to end
connection. Not to mention that this has to be set up prior to aswell, with this it will have near
guaranteed performance.
b. For the remainder of this problem, suppose packet switching is used. Why will there be
essentially no queuing delay before the link if two or fewer users transmit at the same
time? Why will there be a queuing delay if three users transmit at the same time?
When packet switching is used, there will be essentially no queuing delay before the link
if two or fewer users transmit at the same time because the packets from these users can be
transmitted immediately without waiting in a queue. However, if three users transmit at the same
time, there will be a queuing delay because the packets from one or more users will have to wait
in a queue before being transmitted.
.
c. Find the probability that a given user is transmitting.
The probability that one user is active at a time is around 20% or p = 0.2
d. Suppose now there are three users. Find the probability that at any given time, all three
users are transmitting simultaneously. Find the fraction of time during which the queue
grows.
If there are three users we multiply the probability of each user transmitting together p^3
so .2^3 = .008. The moment the queue grows is p = .008
24) . What is an application-layer message? A transport-layer segment? A network-layer
datagram? A link-layer frame?
a) Application-Layer Message is a unit of data echancged between applications, it
represents the data or information generated by a application like a web browser.
b) A Transport-Layer Segment is a unit of data encapsulation at the transport layer of the
OSI model or the TCP/IP model. It represents the data packet created by the transport
layer protocol by adding a transport header to the application-layer message.
c) Network-Layer Datagram is a unit of data at the network layer of the OSI or TCP/IP
model. It represents the data packet created by the network layer protocol by adding a
network header to the transport-layer segment.
d) Link-Layer Frame is a unit of data at the data link layer of the OSI or TCP/IP model. It
represents the data packet created by the data link layer protocol by adding a link-layer
header and trailer to the network-layer datagram.
25) Which layers in the Internet protocol stack does a router process? Which layers does a
link-layer switch process? Which layers does a host process?
Routers processes in the network layer (Layer 3) of the OSI model. Routers make forwarding
decisions based on IP addresses, routing tables, and routing protocols. They route packets
between different networks or subnets. However some routers also process on the data link layer
(Layer 2): Some routers can also operate at this layer, primarily for functions like ARP (Address
Resolution Protocol) for mapping IP addresses to MAC addresses, and for encapsulating packets
into the appropriate data link layer protocol, just like Ethernet.
Link-layer switches, also known as Ethernet switches, primarily operate at the data link layer
(Layer 2) of the OSI model or the Internet protocol stack. Therefore, link-layer switches process:
Data Link Layer (Layer 2): Switches forward frames based on MAC addresses. They learn MAC
addresses by inspecting incoming frames and build a MAC address table (also known as a
forwarding table or CAM table) to efficiently forward frames only to the port where the
destination MAC address is located.
Hosts, such as computers, smartphones, and other network-connected devices, primarily operate
at the upper layers of the OSI model or the Internet protocol stack. Therefore, hosts process:
Application Layer (Layer 7): Hosts run various applications that interact with network services,
such as web browsers, email clients, and file transfer applications.
26) What is the difference between a virus and a worm?
Virus - This is a type of malware that attaches itself to files and other real programs. Viruses
typically spread when the infected program or file is executed by the user. Once executed, the
virus can duplicate itself and attach to other programs or files on the same system. Viruses can
spread through various means such as email attachments, infected software downloads, USBs, or
even file sharing over a network.
Worm - This is a type of malware program that replicates itself and spreads independently
without needing to attach itself to a file or program. Worms can propagate rapidly across
networks by exploiting vulnerabilities and using various communication protocols such as email,
instant messaging, file sharing, etc. Unlike viruses, worms can spread automatically without any
user intervention once they gain access to a vulnerable system.
The main difference between the two is that a virus requires a executable program or file while a
worm doesnt require any of that to duplicate, they are standalone programs that can
independently propagate on its own.