TCP (reliable transmission) netstat -n
TCP Connection-Oriented (Guaranteed Link Establishment with Three Handshake) Reliable Delivery Full Duplex Oriented Byte Streaming Peer-to-Peer (and)
Eg file transfer
How does TCP achieve reliable transmission
Stop waiting for agreement for a round trip time
ARQ automatically retransmits the request
Confirm the missing
- Discard duplicate M1
- Retransmit to confirm m1
Confirmation late
- Accept late confirmation and do nothing
Improved pipeline continuous ARQ
Every time a window needs to be moved until the data before the window is received, the window moved past is sent to the window forward clearance
Improved Cumulative Recognition
TCP implements flow control
The URG is transmitted directly to the sender out of the cache
The SYN request establishes the session
ACK confirms receipt of message
PSH sends constant incoming data into the buffer but does not wait for the buffer to be full before handing it to the next layer.
The sliding window
There is selective confirmation
RTTn = (1-a)RTTo +aRTTne
TCP avoids network congestion
Slow start
$$x =2^n \thinspace\thinspace\thinspace\thinspace \thinspace x< ssthresh (slow start) \ x++ \thinspace\thinspace\thinspace\thinspace Ssthresh <x< CWND (loss of package) (add increment) \\ (re-assignment)ssthresh /=2 \thinspace\thinspace\thinspace\thinspace x=0 \\ x= 2^n \thinspace\thinspace\thinspace\thinspace x< ssthresh\\ x++ \thinspace\thinspace\thinspace\thinspace ssthresh<x< CWND (packet loss) (add increment) \\ $$
Fast recovery
Quick retransmission immediately confirm the lost packet
$$x =2^n \thinspace\thinspace\thinspace\thinspace \thinspace x< ssthresh (slow start) \ x++ \thinspace\thinspace\thinspace\thinspace Ssthresh <x< CWND (lost) (add increment) \\ (re-assignment)ssthresh /=2 \thinspace\thinspace\thinspace\thinspace \thinspace x= CWND /2 \ x++ \ ThinSpace \ ThinSpace \ ThinSpace \ ThinSpace \ ThinSpace SSTHRESH <x< CWnd (Loss of Packets) (Add Increments) \ $$
UDP (Unreliable Transport)
A packet can complete the communication of data
Eg chat multicast
DNS UDP+53 or TCP 53