(2) Suguru Yamaguchi Nara Institute of Science and Technology Department of Information Science
Flow Control Information Network 1 / 2012 2
Flow Control DLL : Automatic Repeat Request (ARQ) Stop-and-wait Go-back-N Selective-repeat Information Network 1 / 2012 3
(Unrestricted) Information Network 1 / 2012 4
Stop-and-wait ARQ (1) Sender t 1 t 5 t 4 t 1 t 2 t 3 Receiver t 1 : Round Trip Time t 2 : Frame Transmission Time t 3 : Frame Processing Time t 4 : ACK Transmission Time t 5 : ACK Processing Time Information Network 1 / 2012 5
Stop-and-wait ARQ (2) 1 ACK 2t 1 +t 2 +t 3 +t 4 / 1 Information Network 1 / 2012 6
Stop-and-wait ARQ (3) Timeout Lost ACK Information Network 1 / 2012 7
Automatic Repeat Request (ARQ) SEQ n ACK n = n+1,, n n n, ACK for n n+1 ACK for n ACK for n n+1 Information Network 1 / 2012 8
Go-back-N ARQ (1) Stop-and-Wait Protocol ACK ARQ ARQ i n i+1,2,3 n ACK Information Network 1 / 2012 9
Go-back-N ARQ (2) ACK e.g. 7 Information Network 1 / 2012 10
Go-back-N ARQ (3) ACK Go-back-N N ACK (on-the-fly frame ) Information Network 1 / 2012 11
Selective-Repeat ARQ (1) Go-back-N Go-back-N Go-back-N ( ) Information Network 1 / 2012 12
Selective-Repeat ARQ (2) Negative ACK (NAK) n ACK Information Network 1 / 2012 13
(Role allocation) : Transport Network Data Link Information Network 1 / 2012 14
HDLC & PPP Information Network 1 / 2012 15
High-Level Data Link Control (HDLC) ISO ISDN Information Network 1 / 2012 16
HDLC Frame (1) Address: Control: Data: Checksum: CRC-CCITT Information Network 1 / 2012 17
HDLC Frame (2) Control Field Control field of: (a) an information frame (b) a supervisory frame (c) an unnumbered frame Information Network 1 / 2012 18
HDLC Frame (3) Control Field 3 : Information frame (I-frame) Supervisory frame (S-frame) ARQ Unnumbered frame (U-frame) e.g. Information Network 1 / 2012 19
X.25 WAN: Wide Area Network LAN (Local Area Network) WAN e.g., ISDN CCITT standard ITU-T standard Layer 1 Layer 3 of the OSI reference model Network layer PLP Data link layer HDLC (ITU-T), LAPB (CCITT) Physical layer X.21 bis Information Network 1 / 2012 20
X.25 Network Model DTE DTE PSN DCE DCE PSE DTE: Data Terminal Equipment DCE: Data Circuit terminating Equipment PSE: Packet Switch Exchange PSN: Packet Switch Network DCE DTE Information Network 1 / 2012 21
Point-to-Point Protocol (PPP) PPP (RFC 1557) : demultiplexing Bit transparency: ( ) : : / PPP over SONET/SDH / 2 Information Network 1 / 2012 22
PPP Data Control Protocol PPP (max. frame length, authentication) For IP: IP IP Control Protocol (IPCP) Information Network 1 / 2012 23
PPP Phase Diagram A / Information Network 1 / 2012 24
Sublayers of the Data Link Information Network 1 / 2012 25
1960 (point-to-point connection) 1970 LAN(Local Area Network) ISO/OSI 8802 IEEE802 IEEE802.2 (ISO8802/2) Logical Link Control (LLC) IEEE802.x Information Network 1 / 2012 26
Sublayers of the Data Link Layer Network Layer ISO/OSI Local Area Network Definitions (8802) CCITT Data link Layer Definition Data link Layer Logical Link Control Sublayer Media Access Control Sublayer 8802/2 LLC 8802/3 CSMA/CD 8802/4 Token Bus 8802/5 Token Ring CCITT X.25 (HDLC/LAPB) Physical Layer Information Network 1 / 2012 27
Logical Link Control (LLC) (1) Unacknowledged Connectionless Service (LLC type1) LAN, real-time traffic (voice/speech) Acknowledged Connection-oriented Service (LLC type2) ( ) Information Network 1 / 2012 28
Logical Link Control (LLC) (2) Acknowledged connectionless Service (LLC type3) (acknowledge) Unacknowledged Connection-oriented Service ( ) Information Network 1 / 2012 29
Media Access Control (MAC) (1) Information Network 1 / 2012 30
Media Access Control (MAC) (2) MAC (multiplexing) Information Network 1 / 2012 31