Networks Part 1 (Overview) Flashcards
What is a computer network?
A collection of computers/nodes connected by communication links (can be wired or wireless).
What is a “network node”?
A device that is connected to a network.
It requires a unique address so it can be found by other devices.
What are the components of a network?
- Applications and Users - things that use the network to get some form of service.
- Host/End System/Node - things that supply or receive data, often interfaces that allow the functioning or access to a network.
- Links/Channels - things that connect nodes (can be wired or wireless)
- Communication Devices/Nodes - relay messages between links towards destination host (Repeaters, NICs, Switches ect..)
What are the different types of networks based on scale?
- Personal Area Network (1 square meter)
- Local Area Network (Room to a Campus)
- Metropolitan Area Network (City)
- Wide Area Network (Country/Continent)
- The Internet (Planet)
What is MANET?
Mobile Ad-hoc Network
A network of nodes that dynamically self organise and allow transfer of data over each other.
E.g In nodes A-B-C, A might be out of range of C, but B can be used as a relay node to transfer data between nodes that would have been out of range from one another.
What is the MANET network?
Mobile Ad-hoc Network
A network of nodes that dynamically self organise and allow transfer of data over each other.
E.g In nodes A-B-C, A might be out of range of C, but B can be used as a relay node to transfer data between nodes that would have been out of range from one another.
What is the RFID network?
Radio Frequency Identification
A network of “Readers” which send signals to “Tag” nodes, labels which have no components or battery. The “Tag” nodes are able to reflect the signals of the “Readers”, which allows it to identify the tag.
This can enable systems such as smartcards or NFC contactless.
What is a “Sensor Network”?
A network where a group of sensors act as nodes. Each sensor collects data, often in different locations, and reports the data back to a central location. The data can then be stored, viewed, and used in analysis.
What is a protocol stack?
A list of interconnected protocols used in a network layer.
What is a “service”?
A set of “primitives” (operations) that a layer provides to the layer above it.
Primitives tell a service to perform an action, or report on an action that has been taken by a peer entity.
What is a “connection-oriented service”?
A service where a connection is first established before sending data. All data sent will travel along the same route. Once it has finished transferring data, the connection is then released.
What is “connection-oriented packet switching”?
A service where no connection is established before sending data. Packets are sent with their full destination address, and make their own way to their destination, often taking different routes through different nodes. They are re-arranged into their correct order upon arriving at their destination.
What is OSI layer 1? What is its data unit?
The Physical Layer
Allows the activation, maintenance and deactivation of end systems by defining the specifications of the:
- Electronic Systems (Voltage levels, timing of signals)
- Mechanical Systems (Physical data rates)
- Procedures (Maximum Transmission Distances)
- Functional Specifications (Physical Connectors)
not super sure on the (stuff)
Data unit is a bit.
What is OSI layer 2? What is its data unit?
The Data-Link Layer
Provides a data transmission service free from transmission errors between adjacent nodes using the physical layer.
It must:
1. Process acknowledgements of received data.
2. Detect and recover from damaged, lost and duplicate frames.
3. Make sure the transmitter doesn’t overload the receiver.
4. Control access to the medium in broadcast networks.
Data unit is a frame.
What is OSI layer 3? What is its data unit?
The Network Layer
Controls how a packet is routed from its source to its destination through a subnet.
It must:
1. Determine a route for each source/destination pair.
2. Perform congestion control (when there are too many messages in transmit)
3. Overcome the problem of switching between network types (moving between LAN and WAN protocols)
Data unit is a packet.
