Feb. 25, 2004 Prof. Paul Lin 1 CPET The Data Link Layer Paul I-Hai Lin, Professor Electrical and Computer Engineering Technology Purdue University, Fort Wayne Campus

Feb. 25, 2004 Prof. Paul Lin 2 Topics of Discussion Data Link Layer Design Issues Data Link Layer Design Issues Error Detection and Correction Error Detection and Correction Elementary Data Link Protocols Elementary Data Link Protocols Sliding Window Protocols Sliding Window Protocols Protocol Verification Protocol Verification Example Data Link Protocols Example Data Link Protocols

Feb. 25, 2004 Prof. Paul Lin 3 Functions of the Data Link Layer Receive services from physical layer layer Receive services from physical layer layer Provide services to the network layer (upper) Provide services to the network layer (upper) Unacknowledged connectionless serviceUnacknowledged connectionless service Acknowledged connectionless serviceAcknowledged connectionless service Acknowledged connection-oriented serviceAcknowledged connection-oriented service Communication control Communication control Establishment of linkEstablishment of link Transfer dataTransfer data De-establishment of linkDe-establishment of link

Feb. 25, 2004 Prof. Paul Lin 4 The Data Link Layer Design Consideration Control and Management of Data Transfer Control and Management of Data Transfer Data DescriptionData Description Control DescriptionControl Description Handshaking ProceduresHandshaking Procedures Data Frame - Header or Control + Data Information + Trailer (CRC error checking)Data Frame - Header or Control + Data Information + Trailer (CRC error checking) Topology Topology Point-to-pointPoint-to-point Multi-point or BroadcastMulti-point or Broadcast

Feb. 25, 2004 Prof. Paul Lin 5 The Data Link Layer Design Consideration (continue) A protocol layer that performs the following tasks A protocol layer that performs the following tasks Packetizing - forming a virtual path for transmitting the data bitsPacketizing - forming a virtual path for transmitting the data bits Data framing - break data bits (from layer 3) into frames and compute checksum for each frame; will be recomputed by the receiving sideData framing - break data bits (from layer 3) into frames and compute checksum for each frame; will be recomputed by the receiving side MAC (Media Access Control) AddressingMAC (Media Access Control) Addressing CRC (Cyclic Redundancy Code) Error CheckingCRC (Cyclic Redundancy Code) Error Checking Error control – Positive Ack., Negative Ack; timer; frame sequencingError control – Positive Ack., Negative Ack; timer; frame sequencing Flow control – transmission rate or speedFlow control – transmission rate or speed

Feb. 25, 2004 Prof. Paul Lin 6 Examples of Data Link Protocols HDLC – High-Level Data Link Control (ISO modified SDLC) HDLC – High-Level Data Link Control (ISO modified SDLC) SDLC – Synchronous Data Link Control (IBM -> ANSI and ISO)SDLC – Synchronous Data Link Control (IBM -> ANSI and ISO) ADCCP – Advanced Data Communication Control Procedure (ANSI modified SDLC)ADCCP – Advanced Data Communication Control Procedure (ANSI modified SDLC) LAP - Link Access Procedure (CCITT modified HDLC as part of X.25 network interface standard)LAP - Link Access Procedure (CCITT modified HDLC as part of X.25 network interface standard) LAPB – an updated version of LAPLAPB – an updated version of LAP

Feb. 25, 2004 Prof. Paul Lin 7 Examples of Data Link Protocols Data Link Layer in the Internet Data Link Layer in the Internet PPP - The Point-to-Point ProtocolPPP - The Point-to-Point Protocol Including router-to-router traffic and home user-to-ISP traffic (Modems, ADSL, Cable Modems)Including router-to-router traffic and home user-to-ISP traffic (Modems, ADSL, Cable Modems) RFC 1661 PPP PPP RFC 1662 PPP in HDLC Like Framing H PPP in HDLC Like Framing H RFC 1663 PPP Reliable Transmission PPP Reliable Transmission

Feb. 25, 2004 Prof. Paul Lin 8 Examples of Data Link Protocols IEEE 802 Standards subdivides the data link layer into two sub-layers IEEE 802 Standards subdivides the data link layer into two sub-layers Logical Link Control (LLC)802.2 Logical Link Control (LLC) Media Access Control (MAC): CSMA- CD, Token Ring, Wireless LAN, etcMedia Access Control (MAC): CSMA- CD, Token Ring, Wireless LAN, etc LLC MAC

Feb. 25, 2004 Prof. Paul Lin 9 Examples of Data Link Protocols Data Link for Wireless Sensor Network Data Link for Wireless Sensor Network czhong/documents/milcom_2001_final.pdfhttp://bwrc.eecs.berkeley.edu/People/Grad_Students/ czhong/documents/milcom_2001_final.pdfhttp://bwrc.eecs.berkeley.edu/People/Grad_Students/ czhong/documents/milcom_2001_final.pdfhttp://bwrc.eecs.berkeley.edu/People/Grad_Students/ czhong/documents/milcom_2001_final.pdf Other Layer 2 Examples Other Layer 2 Examples ISDN Fiber Data Interface, VLAN, etc Data Interface, VLAN, etc IEEE 802.1Q Tunneling 708/products_configuration_guide_chapter09186a f00d.htmlIEEE 802.1Q Tunneling 708/products_configuration_guide_chapter09186a f00d.html 708/products_configuration_guide_chapter09186a f00d.html 708/products_configuration_guide_chapter09186a f00d.html