OSI (3-7) Flashcards
Logical Addressing
IP, IPX, AppleTalk
Layer 3
Switching
Forwarding decisions Packet Switching Circuit Switching Message Switching Layer 3
Packet Switching
AKA routing
Data stream divided into packets with Layer 3 header with source and destination address
Circuit Switching
Dynamically brings up a dedicated communication link between two parties.
e.g. phone call
Layer 3
Message Switching
Not well suited for real-time applications
Data stream divided into messages tagged with destination address
Affiliated with store-and-forward network
Connection Services
Improve communication reliability
Flow (congestion) control
Packet reordering
Layer 3
Flow Control
aka Congestion Control
Prevents sender from sending data more rapidly than receiver can handle
Packet Reordering
Packets placed in proper sequence
Layer 3 devices
Router, multilayer switch
TCP
Transmission Control Protocol
Connection-oriented transport protocol
Reliable
UDP
User Datagram Protocol
Connectionless transport protocol
Unreliable
Layer 4 flow control
Windowing
Buffering
Windowing
Used by TCP
Multiple segments can be set at a time, receiver sends single acknowledgement for all in window
RTT
Round-Trip Time
aka Real Transfer Time
Time receiver has to acknowledge receipt of window
Buffering
Device uses chunks of memory to store segments if bandwidth not available to send
