Transport Layer
Two protocols:
the TCP: connection oriented transport layer protocol, only one tcp has two ends, each tcp only connection point to point (one to one) would need to transfer the file segment transfer. Session is established, reliable transmission (transmission is reliable, it was found pass over the document sequence error, then send a command to), traffic is transmitted, full duplex communication, the byte stream oriented.
UDP: a packet to complete the file transfer protocol called UDP, no staging, no session is established, unreliable transport, do not flow control. It is responsible for issuing, is not responsible for the other, there is no congestion control, support one to one, one to many, many to many, it's first 8 bytes.
UDP:
TCP
TCP connection has two ports: IP Address and Port
acknowledgment is lost: their past data, the other party to respond to my bag did not receive lost, that I will send a similar packet, the first before the other will put a packet drop, keep the most recent data packets give me a reply packet
to confirm late: after the first transmission of data packets each other for a long time I have not received a reply packet, overtime and I made the same packet and then the other side gave me a reply he received packets to recover data before this time to pack up, I accept to confirm late, but do nothing.
QQ chat using the UDP protocol, file transfer protocol is TCP
email is TCP
UDP multicast and broadcast applied
netstat -n: computer for viewing active sessions
netstat -nb: You can view the session process in the computer which position , what is the application of hair
Port common application-layer protocol that is used:
the HTTP = the TCP + 80
the HTTPS = the TCP + 443
the RDP = the TCP + 3389
the FTP = the TCP + 21 is
shared folder = the TCP + 445
the SMTP = the TCP + 25
the TELNET = the TCP + 21 is
the POP3 = the TCP + 110
+ 53 = UDP the DNS
SQL TCP + 1433 =
