Computer Network Overview Flashcards
(12 cards)
Define Computer Network
Group of devices that are connected to offer certain services
What are End Devices “Hosts”
- Source or destination of messages
- Must have a unique physical or logical address
○ unique - static
○ e.g. IP-Address (logical)
○ MAC-Address (physical)
Peripheral devices properties
Don’t have logical address
Rely on connected host for communications
Network Media
Metallic “copper wires”, electrical pulses
Protocol Stack (Suite)
A group of protocols that work together to ensure successful communication
OSI (Reference) Model
1.7 Application
1.6 Presentation
1.5 Session
1.4 Transport
1.3 Network
1.2 Data Link
1.1 Physical
TCP/IP (Protocol Model)
- Application
- Transport
- Internet
- Network Access
What is segmentation in the TCP/IP stack?
The transport layer (TCP/UDP) breaks large application-layer messages into smaller, numbered chunks called segments so they fit below the Maximum Segment Size (MSS).
Why is segmentation needed?
Smaller chunks reduce retransmit cost and let multiple flows share the link fairly.
Where are segment pieces re-joined?
At the destination transport layer: TCP uses sequence numbers + acknowledgment to reorder and reassemble the byte stream.
Define encapsulation in one sentence.
As data moves down the stack, each layer wraps the payload it receives with its own header (and sometimes trailer), forming a new PDU for the layer below.
What is added at the data-link layer during encapsulation?
Frame header (dest MAC, src MAC, EtherType) and trailer (FCS checksum).
Contrast segmentation vs. IP fragmentation.
Segmentation is done by the sender’s transport layer before handing data to IP.
* Fragmentation is done by routers when an IP packet exceeds a link’s MTU; each fragment gets its own IP header with offset/flags.
