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Transport Layer - Coggle Diagram
Transport Layer
TCP
reliable and in-order
one sender - one receiver
Congestion and Flow control set win size
Flow
Receiver control
set by rwnd value
Congestion
Sender control
Tahoe: restart from 1
Reno: restart from ssthresh
ssthresh set 1/2 of cwnd, increase by 1 after ssthresh
MSS: maximum segment size
full duplex data : bi-directional data flow in same connection
Segment Struct
sequence num: first byte of byte stream of seg
acknowledgement num : next expect byte stream num.cumulative
Connection-orientated
3-way handshake
init close first,receiver close class
UDP
best efford
connectionless: no handshaking
add reliability at app layer
no congestion control : blast away as fast as poss
Multiplexing: add transport header / Demulti : use header to define socket
Connectionless Demulti : Dest PORT/IP
Connection-Orientated : 4 tuples
Reliable Data Transfer
rdt 3.0
Performance
U= (L/R)/(RTT + (L/R))
stop and wait: low util
Pipelined: multiple in-flight packet
Go-Back-N
receiver send: cumulative ACK (does not ACK if gap)
Timer for oldest unACK-pack, restransmit all unACKed packet
Selective repeat
receiver send individual ACK
Timer for each unACK packet, retransmit only that unACK
pass segment to network layer
logical communication between processes