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1 Computing AS Level (JoshH) > Network Topologies > Flashcards

Flashcards in Network Topologies Deck (28)
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1

What hardware do we require for a computer to be able to join a network?

Network Adapter (Network Interface Card - NIC)
Router
Client Device
Server

2

What is the NIC

This is the specifically designed to allow the computer to a network (Wired or Wireless)

3

What is the Router

Router provides the link between devices in your network and any servers or the internet.
Modern Routers also:
Receive every packet of data and routes them to the correct destination
Act as a switch(creates the connection between devices)
Act as a firewall
Acts as wireless access point
Act as modem (converting digital signals to analogue)

4

What is the client device

The client device is a piece of computer hardware or software that accesses a service made available by a server on a network.
AKA the device that the user is using

5

What is the server

A Server is the computer device or program that provides a service to client over the internet. Commonly the server is a dedicated machine that provides a sole service.
Example:
Web Server
Mail Server
File Server

6

Why is it good to use networks?

Connect to the internet
Collaborate on documents
Share software
Share files
Message each other

7

3 features of a LAN

High speed
Small geographical area
Usually owned by a single person/organisation

8

3 features of a WAN

Operate over larger distances
Link LANs together
Internet is an example
Collective or distributive ownership

9

3 features of a PAN

Organised around an individual
Often involve phones, tablets etc and use bluetooth
Typically within a range of 10 metres

10

Draw a star topology

Each computer is individually connected to a central point that is usually a switch

11

What are switches?

All of the computers on the network plug into a port on the switch using a cable
They transmit the data being sent from one node to the other
They can read destination addresses and send the only to the intended computers (They build up a table of MAC (machine access code) addresses)

12

Pros of a star topology

Fast connection due to dedicated communication channel to each client
Less traffic even when other users are online
Fault finding becomes easier to trace
Relatively secure as connection is not shared
New clients easily added without affecting other clients
If 1 cable fails the rest of the network is unaffected

13

Cons of a star topology

Expensive to set up due to cable costs (need a cable for every device
If cable does fail, the client is unable to receive data
Difficult to install as multiple cables are required. If LAN is split across buildings then this is made worse
The server can become congested as all communications must pass through it.

14

How does a star network work?

The switch or hub keeps a record of each node's unique MAC address.
When requests and data are received the switch will identify where to pass the data on to.

15

Draw a bus network

Main server is accessed off one main cable (often called the backbone)
Each client and device is branched off from backbone.
Signals are sent and received by every device,
Terminators exist at either end to prevent signals bouncing back and forth.

16

How does a bus network work?

In a bus network data cannot be transmitted simultaneously in both directions.
Every station will receive all network traffic and each station has equal transmission priority.
A device will send out a broadcast message to the network but only the intended recipient will accept and process the message.

17

What does CSMA/CD stand for?

Carrier Sense Multiple Access with Collision Detection

18

What is CSMA/CD

If 2 nodes try to transmit simultaneously, a carrier sensing scheme detects other signals while transmitting a frame. Both Nodes stop transmitting and wait for a random time before retrying.

19

Pros of bus network

Cheaper to install than a star network as only 1 main cable required
Easier to install
Easy to add new clients by branching them off the new clients

20

Cons of a bus network

Less secure than a star as all data is transmitted down backbone
Transmission times get slower when more users are online
If the main cable is affected, all clients are affected
Less reliable than a star network due to reliance on main cable
More difficult to find a fault when one occurs

21

Define Physical topology

Physical topology - is the actual connection of cables

22

Define Logical topology

Logical topology - the conceptual way in which data is transmitted

23

Features of a Peer to Peer Network (P2P)

There is no central server
Individual devices are connected to each other, Computer are equal = peers
Share files stored on the devices
Video on demand is often distributed via P2P networks as hundreds of computers can hold part of the video therefore sharing the load.
No central control (normally no administrative computer)
Each computer can be personalised to determine what data, disk space, peripherals on their computer can be shared on the network

24

Peer-to-peer; suitable for?

Fewer than 10 users
Located in the same areas
No security concerns (or user knowledge concerns)
Limited growth in the future

25

Features of Client - Server Networking

One or more devices (Client) are connected to a powerful central computer called a Server.
Each client may have its own files but..
Server holds resources for clients to use
May be more than 1 server:
File Server - Mail Server - Web Server etc.
Used with more than 10 users
Network security, resources, admin and other functions dictated and provided by servers

26

What are WPA and WPA2

Security Protocols
Wi-Fi Protected Access (2)
Built into wireless network cards, providing encryption of data transmitted from the card. WPA2 uses 128-bit key, generated for each packet sent.

27

What is Service Set Identification (SSID)

Identify the network - Informal name of the local network (WPS-Chrome)
Usually followed by a security key (upto 32 bytes) usually a string
These are commonly set by ISP
Lots of people change them
SSIDs must be locally unique

28

What is one issue with bus networks?

Collisions can occur because data can be transmitted in both directions.
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is used to prevent collisions. CSMA/CD (detection) will only detect issues and not stop them.