Unit 1 STQ 201-204 Flashcards
Into what two categories can the OSI model be divided?
- Application layer (upper)
2. Data Transport layer (lower)
What are the responsibilities of the Data Transport layers of the OSI model?
Defines how data is sent across the physical media, through Internetwork devices, to the destination computer, and to the application on the destination machine
This layer’s specifications include physical addressing, sequencing of frames, and flow control
Data Link or Layer 2
This layer typically includes multiplexing, virtual circuit management, and error checking and recovery
Transport or Layer 4
This layer typically defines the electrical, mechanical, procedural, and functional specifications for network communications
Physical or Layer 1
A hub operates at this layer
Physical or Layer 1
TCP operates at this layer
Transport or Layer 4
Switches and bridges operate at this layer
Data Link or Layer 2
This layer provides routing and related functions that enable multiple data links to be combined into an Internetwork
Network or Layer 3
This layer provides a variety of coding and conversion functions that are applied to application layer data
Presentation or Layer 6
A router operates at this layer
Network or Layer 3
Telnet, FTP, and SMTP that exist in the TCP/IP suite operate at this layer
Application or Layer 7
This layer establishes, manages, and terminates communication sessions between presentation layer entities
Session or Layer 5
At this layer, common data compression and encryption schemes are used
Presentation or Layer 6
What is a physical topology?
It is the layout of the network media that interconnects the devices on a network
What is a logical topology?
It defines the way in which devices communicate and data is transmitted throughout the network
What is the rule of thumb to distinguish physical from logical topologies?
If you can see it and touch it, it’s physical. If you cannot see it or touch it, it’s logical
A topology affects the network’s capabilities; what is the impact of choosing one topology over another?
- Equipment type
- Equipment capabilities
- Network growth
- Network management method
What are the advantages of a bus topology?
- Works well for small networks (2-10 devices)
- Inexpensive to install (esp. Thinnet)
- Requires less cable
- Easy to add wksts
What are the disadvantages of a bus topology?
- No longer recommended for new installs
- Backbone breaks -> network is down
- Number of devices can include is limited
- Problem isolation is difficult
- Slower access time
What are the advantages of a star topology?
- Easy to add devices
- Failure of one cable will not bring down entire network
- Hub provides centralized management
- Easy to find device and cable problems
- Can be upgraded to faster network speeds
- Most common topology–many equipment options
What are the disadvantages of a star topology?
- Requires more media than a ring or bus network
- Failure of the central hub can bring down the entire network
- Installation & equipment costs are higher than most bus networks
What are the advantages of a ring topology?
- Data packets can travel faster
- No collisions
- Easier to locate device & cable problems
- Terminators not needed
What are the disadvantages of a ring topology?
- Requires more cable than a bus network
- Break in the cable will bring down many ring networks
- All devices suspended from the network when new devices are added
- Limited amount of equipment available
