<Jeremy's IT Lab> Day 30: TCP & UDP

TCP & UDP

: L4 (Transport layer)

-> transparent transfer data btw end-host

-> provide

   - reliable data transfer

   - error recovery

   - data sequencing

   - flow control

-> provide L4 addressing (port#) (NOT physical int/port)

   - identify Application Layer protocol

   - session multiplexing

   - designated by IANA (Internet Assigned Numbers Authority)

• well-known port #: 0 ~ 1023
• Registered port #: 1024 ~ 49151
• Ephemeral/ Private/ Dynamic port #: 49152 ~ 65535

 

TCP(Transmission Control Protocol):

(1) Connection oriented 

   -> Establishing : Three-way Handshake

    SYN ------------->

    <-------ACK, SYN

    ACK-------------->

   -> Terminating : Four-way Handshake

    FIN ------------->

    <-------------ACK

    <--------------FIN

    ACK-------------->

 

(2) reliable communication (sent again not acknowledged segment)

    Seq: 20 -------------------------->

    <--------------------------ACK: 21

    Seq: 21 -----X-->

    Seq: 21 -------------------------->

 

(3) sequencing

    Seq: 10 -------------------------->

    <--------------Seq: 50 , ACK: 11

    Seq: 11, ACK: 51 -------------->

 

(4) flow control 

  - window side: sliding window (dynamically adjust size)

 

UDP(User Datagram Protocol):

(1) X Connection oriented 

(2) X reliable communication

(3) X sequencing

(4) X flow control 

 

TCP	UDP	TCP& UDP
FTP data (20)	DHCP server (67)	DNS (53)
FTP control (21)	DHCP client (68)
SSH (22)	TFTP (69)
Telent (23)	SNMP agent (161)
SMTP (25)	SNMP maneger (162)
HTTP (80)	Syslog (514)
POP3 (110)
HTTPS (443)