Computer Networking

CS 465

What is the Internet?

The internet is a HUGE number of connected computer, all running on the same protocol.

Endsystems are connected to the internet via what?

links (wired and wireless)

What are link speeds measured in?

bits/second (bps)

List the four types of links

Copper wire, coaxial cable, fiber optics, and satellite (radio)

What type of link is used in landlines?

Copper wire

What type of link is used in TV cables?

Coaxial cable

Which is faster: copper wire or coaxial cable

coaxial cable

What type of link uses light?

Fiber optics

What type of link is used at the bottom of oceans?

Fiber optics

What type of links easily snap and are difficult to fix?

Fiber optics

What type of link is uses in radios and starlink?

Satellite

Why may satellite links be preferred over other links?

Larger range

What directs traffic through the internet?

Packet switches

Can multiple paths/routes be taken in the internet?

Yes, multiple paths can be taken through different links (if another/faster link is congested)

What is the most popular protocol?

TCP/IP

Why should protocols be detailed?

Protocols are how computers/devices communicate with one another. If a protocol is not detailed enough, then the two communicating computers will not understand each other.

What are the two sides of an endsystem/host?

Client and server

Give a brief description of a client.

A client is asking for data from the server (phone, laptop, etc).

Give a brief description of a server.

A server has the data in which the client wants and distributes that data to the client.

What is the difference between a host and an end system?

A host and end system refer to the same thing, and can be used interchangeably.

Give a few examples of hosts or end systems?

Phone, computer, fridge, TV

Why are protocols necessary in computer networking?

Protocols are the rules in place which allow devices to communicate with one another; they are extremely detailed. All computers should be running the same protocol.

What is an ISP?

An Internet Service Provider is someone (a company) who provides an internet service to a consumer base.

What is an edge router?

An edge router is the nearest router which gets your end system onto the internet.

Name at least three different types of access technologies.

Three examples of access technologies are coaxial cables, fiber optic cables, and satellites.

What are access technologies?

Way in which you can connect to the internet.

What does IETF Stand for?

Internet Engineering Task Force

What does RFCs standing for?

Requests for Comments

What is an IETF?

Maintains the documents and the standard RFCs

Describe a distributed application.

Typically involve multiple end systems, but can be run on one machine using multiple process.

What do sockets need to know?

IP’s, Process ID’s, and ports

What is DSL Internet Access?

Uses digital subscriber lines to transmit data over copper wire. DSL modem connects to the DSLAM using a splitter to break down frequencies (this is how a phone can be used while someone is on the internet in the same house).

What is a Hybrid Fiber-Coaxial Access Network

Broadband network that combines fiber-optic and coaxial cable to deliver internet and cable services. It uses VoIP (Voice over IP). CMTS located in cable head end send data in and out to/from the internet.

What is FTTH Internet Access

Uses fiber optic cables to send traffic directly to house (ONT), meaning after the optical splitter no traffic is shared. It’s expensive and not easy to repair if broken. FTTH is usually only found in large cities.

Ethernet Internet Access

Sets of standards and protocols to send data. Uses a ethernet switch to send data to institutional router before going to the institutional ISP. Includes PAN, LAN, WAN/MAN.

DOCSIS

international telecommunications standard that enables high-bandwidth data transfer over an existing coaxial cable TV system. Protocol for modems.

Whats the difference between DOCSIS versions 3.1 and 4

Both versions have an upload speed of 1-2 Gbps, and a download speed of 10 Gbps. However, version 4 introduces latency, better efficiency, and more frequencies.

What is a distributed application?

Any program/process that runs on multiple hosts or processes that exchange information.

What is a socket?

Software endpoints for network communications.

What is socket interface?

The API that allows us to create and use dockets.

Describe Circuit Switched Network.

Old/outdated. How the landline system works. Build the circuit before sending any data. Expensive to build and you must close the circuit when not actively using.|
FDM (Frequency Division Multiplexing) and TDM (Time Division Multiplexing)

What is FDM?

(Frequency Division Multiplexing) each user will get assigned a frequency to use. Bleeding (interference between frequencies) may occur, so a buffer is required. Expensive to run and maintain.

What is TDM?

(Time Division Multiplexing) each user gets a sliver of a frequency at a certain time slot. This is a preferred method. Higher cost, more material, and more time effective than FDM.

Describe a Packet Switched Network.

No path is made before communication starts; instead a path is based on speed, distance, and/or congestions.

At times you can get very fast speeds; but if there is large congestion, then you’ll have slow or maybe even no connection.

What are the types of nodal delays at a router. Include descriptions and formula’s if applicable.

d_proc (Processing Delay): time to examine a packet header and decide which link it will be transmitted over.

d_trans (Transmission Delay): the time to push the bits onto a line. (Packet Length or Size)/(Transmission Rate)

d_queue (Queuing Delay): the time a packet waits in the buffer for packets that arrived to the node before it’s transmitted.

d_prop (Propagation Delay): the time for the bits to travel from one node to another across the link. (Length of Link)/(Propagation speed)

Total Delay: the sum of all nodal delays on a link. d_proc+d_trans+d_queue(if applicable)+d_prop

What are the layers in the Internet Protocol Stack?

Application Layer (message): distributed applications that exchange data (e.g. HTTP, SMTP, SFTP).

Transport Layer (segments): messages between two endpoints; ports. (e.g. TCP, UDP)

Network Layer (datagrams): path determination and local addressing.

Data Link Layer: physical addressing.

Physical Layer: Media, signal, and binary transmission.