3213 Quiz 1 Flashcards
What is ARPANET
-Type of connection, and name?
Computer to computer network
Wide area network
How does ARPANET work
Switched network infrastructure
Packets of fixed size
What is circuit switching? (Wired telephone network)
Pros/Cons?
Dedicated path between 1 or more links
Pros: Guaranteed QoS, fixed transmission rate, no data loss
Cons: Inefficient, and complex. One connection suffocates link vs packet switching
What is Packet switching (ARPANET, Internet, 3G+)
Pros/Cons?
No dedicated path, packets transmitted independently.
Pros: links shared by many packets, packets accepted even under heavy traffic.
Cons: No QoS guarantee, packet delay/loss during traffic, overhead encapsulation traffic.
LAN network topologies
Bus Topology
- Simple/inexpensive
- Single point of failure, collision = diminishing capacity
Ring Topology
- small frame (token) circulates dictating who can transmit data
- Fair access
- Breaks if any link fails
Star topology
- Each station connected directly to central node
- Central node broadcast and/or switch
Hub vs Switch?
Only one station can transmit otherwise collision occurs, and broadcast data to all connected computers
Switch: Sends data only to specified computers.
IP Addressing (Address format + Routing)
IP Address = Net ID + Host ID
IP Packets are routed only based on Net ID in destination IP Address
- Only has to know major networks/ smaller routing table -> Faster routing
What is a protocol and its data unit type?
Set of rules that govern how two or more entities in a layer are interacting
ex: HTTP, TCP, IP
Communicate by exchanging Protocol Data units (PDU’s)
What are services
Services wrapped in PDU’s, available at Serice Access Points (SAP)
layer n+1 transfers info by invoking services by layer n
What is a Data link layer?
4 Main actions
Attempts to provide reliable communication over physical layer(same network)
Divides stream of bits into frames
adds header to specify address of receiver (MAC)
Adds trailer to header to detect/recover lost frames
Flow control
What is a Network Layer
- Addressing, Routing, frag
Oversees delivery of packets between devices across multiple networks/links
- Logical addressing / scale to large networks
- provides routing for optimal path across large internetwork
- Fragmentation and reassembly of packets to accommodate different media.
What is a transport layer?
Purpose
Network layer gets packet to receiver, transport gets entire message to correct process on receiver.
- Reliable mechanism for process to process
- Ensures data units are delivered error free, in sequence, with no loss/dup
Transport Layer supporting purpose
- Addressing, segment, flow
Port addressing: Specifies port address to send to receiver
Segmentation and reassembly: Divide into segments containing sequence number, to reassemble message correctly, and identify/replace missing packets.
Flow and error control: Performed end to end
The application layer does what?
Provides actual service/ interface to the user
OSI Downfall reason?
TCP/IP Launched same time with 5 layer, less complex, more efficient