1. Feb. 25, 2004 Prof. Paul Lin 1 CPET 355 3. The Data Link Layer Paul I-Hai Lin, Professor Electrical and Computer Engineering Technology Purdue University, Fort Wayne Campus

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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 http://www.faqs.org/rfcs/rfc1661.htmlRFC 1661 PPP http://www.faqs.org/rfcs/rfc1661.html http://www.faqs.org/rfcs/rfc1661.html RFC 1662 PPP in HDLC Like Framing H http://www.faqs.org/rfcs/rfc1662.htmlRFC 1662 PPP in HDLC Like Framing H http://www.faqs.org/rfcs/rfc1662.html http://www.faqs.org/rfcs/rfc1662.html RFC 1663 PPP Reliable Transmission http://www.faqs.org/rfcs/rfc1663.htmlRFC 1663 PPP Reliable Transmission http://www.faqs.org/rfcs/rfc1663.html http://www.faqs.org/rfcs/rfc1663.html

8. 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 802.2 Logical Link Control (LLC)802.2 Logical Link Control (LLC) Media Access Control (MAC): 802.3 CSMA- CD, 802.5 Token Ring, 802.11 Wireless LAN, etcMedia Access Control (MAC): 802.3 CSMA- CD, 802.5 Token Ring, 802.11 Wireless LAN, etc LLC MAC

9. Feb. 25, 2004 Prof. Paul Lin 9 Examples of Data Link Protocols Data Link for Wireless Sensor Network Data Link for Wireless Sensor Network http://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.pdfhttp://bwrc.eecs.berkeley.edu/People/Grad_Students/ czhong/documents/milcom_2001_final.pdf Other Layer 2 Examples Other Layer 2 Examples ISDN http://www.ralphb.net/ISDN/proto_l2.htmlISDN http://www.ralphb.net/ISDN/proto_l2.htmlhttp://www.ralphb.net/ISDN/proto_l2.html Fiber Data Interface, VLAN, etc http://www.protocols.com/pbook/lan.htmFiber Data Interface, VLAN, etc http://www.protocols.com/pbook/lan.htm http://www.protocols.com/pbook/lan.htm IEEE 802.1Q Tunneling http://www.cisco.com/en/US/products/hw/switches/ps 708/products_configuration_guide_chapter09186a00 8019f00d.htmlIEEE 802.1Q Tunneling http://www.cisco.com/en/US/products/hw/switches/ps 708/products_configuration_guide_chapter09186a00 8019f00d.html http://www.cisco.com/en/US/products/hw/switches/ps 708/products_configuration_guide_chapter09186a00 8019f00d.html http://www.cisco.com/en/US/products/hw/switches/ps 708/products_configuration_guide_chapter09186a00 8019f00d.html