Tutorial Flashcards
List the 7 layers of the OSI MODEL
Layer 7 Application Layer 6 Presentation Layer 5 Session, 4 Transport, 3 Network, 2 Data-Link 1 Physical
Describe the purpose of each OSI Layer
Physical: defines all electrical and physical specifications for devices major function: Establishment and termination of a connection to a communications medium. Media, Signal and Binary Transmission. Modulation or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel.
Data-link layer:
Provides a functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer.
Network Layer:
Routes messages through complex networks
Transport Layer: Is responsible for assembling packets into their proper sequence, checking for errors and passing them to the session layer.
What is bandwidth
The amount of data that can be transmitted over a network cable at one time.
what is attenuation?
The gradual weakening of a signal as it passes through a wire or other medium
Advantages of Unshielded Twisted Pair (UTP) over Shielded Twisted Pair (STP)
UTP is inexpensive, easy to install due to no special connectors, Lighter , smaller diameter, less rigid
Advantages of Shielded Twisted Pair (STP) over Unshielded Twisted Pair (UTP)
Shield is electrically grounded reducing emissions and susceptibility to EMI. Less susceptible to cross talk, greater bandwidth
Advantages of Fibre Optic Cables
No susceptibility to EMI or Cross talk , much greater bandwidth, greater cost, difficult to install, special connectors required, fragile
Name and Draw the LAN physical Topologies
Bus, Star, Ring, Mesh, Hybrid
What is the difference between physical and logical topologies?
physical topology describes the network you can see, whereas the logical topology desribes the network from the viewpoint of the data travelling on the network
What is the ethernet notation
n signal m
n = Data rate in MBps
m= T for UTP/STP networks and X for fibre networks
signal = signalling type (base for base band/ broad for broadband)
What are the internetworking devices?
Repeaters
Hubs
Switches
Bridges
Routers
Gateways
What are the 3 techniques used for moving data through switched networks? + Diagrams
Circuit switching, Message Switching, Packet Switching
Describe the Internetworking devices (Repeaters, Bridges, Routers,Gateways) and their layers of operations
Repeaters: transmit signal over greater distances , operate Physical Layer
Bridges: Connect two or more network segments, Data link layer
Routers: Connect two or more network segment and send packets to their appropriate destinations, and can thus be used to reduce network traffic in each segment Operates in layer 3
Gateways: Gateways operate at layers of the OSI model ranging from the application layer to the transport Connects netowrk segments are used to translate between protocols and data formats
What is a VLAN + diagram of a VLAN
Virtual Local Area Network, Allows a network to become larger however separate the traffic in order to ensure a faster network by reducing traffic flow as well increasing security.
What is the Class B subnet mask?
255.255.0.0
What is a domestic IP address?
192.168.0.0-192.168.255.255
What is inspected by packet filtered firewalls?
Individual Data packets compared against a set of rules which will drop or reject packets
What is the definition of a Combat System?
Set of person and machine resources which comprise the fighting capabilities of the vessel. Inc. Weapons, Sensors, intelligence, CMS, information systems
What is the definition of a combat management system?
A military management system comprising a close integration of person and machines which together enable: production of a comprehensive tactical picture, formulation and issuing of directives for the deployment of available resources, monitoring compliance with directives and modifying them
What are the primary time-critical components of naval Command and Control?
Tactical Data Fusion, Situation Assessment, Resource Allocation, Resource Planning
What is the generic Combat System Model?
Page 7 CMS
What are the CMS time scales and their ranges?
Long Term: Major Sea areas, day-months
Medium Term: 1000s of miles, hours-days
Current: few hundred miles. seconds to minutes
Immediate: limited ranges of information’s in changes to the current environment, minutes to fractions of seconds
What is the definition of a command System?
Logical grouping of personnel and machines responsible for the immediate to current activities of the Combat Management System and for the management of the Combat System in the short term.
What is the definition of the Command Support system?
Logical grouping of personnel and machines responsible for the medium to long term activities: inc Medium & long term planning, Organic & non-organic information fusion, management of non-organic information systems
What is a centralised CMS system? + characteristics
A centralised structure comprises one central functional processor carrying out all data handling compilations and control function
1.) Difficult and expensive to amend/enhance
2.) single point of failure, limited redundancy
3.) Vulnerable point to point links
4.) Heavy loading on central computer
What is a federated CMS system? + Characteristics
A federated structure which comprises a number of of subsystems which are autonomous in data handling to a certain degree, but are still controlled to a certain degree by one controlling computer
1.) Load on central computer reduced
2.) Still require controlling computer
3.) Degree of distributed processing
4.) Utilises serial highway or LAN so increased flexibility for expansion
5.) Communication protocol or standard required
What is a distributed CMS system? + Characteristics
A Distributed structure which divides the data handling load via the processors in the system without using fixed or central points. In essence blade server technology
1.) No single point of failure
2.) Complex data handling required
3.) Increased redundancy - single member system loss does not affect whole system
4.) Utilises serial highway or LAN so increased flexibility for expansion
5.) communication protocol or standard required
Draw the functional grouping/Hybrids with the Combat System.
Page 15
How is the effectiveness of the CSH maintained?
CSH combat system highway, HCHM Highway controller health monitoring, If a fault occurs the HCHM will log the fault and broadcast the details in a Highway State Message (HSM) so that a maintainer can take proper repair action.
What are the operational Requirements of CSS?
Display the recognised Maritime Picture (RMP)
Display the wide area picture
Provide added value information
Communications Access to shore HQs
Access Shore Databases
Provide encyclopaedic data
Decision and Planning Aids
What impact will NEC have on defence?
1.) Timely information and intelligence
2.) Integration of sensors, decision makers, weapons platforms and support capabilities to enable agility and thus permit commanders to better synchronise effects
3.) Reduction of fratricide
4.) Increased interoperability and collaboration
5.) efficient use of available resources
6.) establishment of common standards
7.) Effective UK homes defence
What are the 3 levels NEC operates at?
Strategic, Operational, Tactical
What are possible problem areas of NEC?
Over-Control, Information Overload, Information Assurance, Procurement
