1. Physical and Data Link Layers Chapter 2 Connecting People To Information

2. Upon completion of this chapter, you will be able to perform the following tasks: Identify and describe the data link sublayers and their functions Explain the use of MAC addresses Describe the topology and functionality of LANs Differentiate between LAN and WAN protocols Objectives

3. Connecting People To Information Physical and Data-Link Standards Separate physical and data link layers for LAN and WAN Physical (bits, signals, clocking) Data Link (frames)

4. Connecting People To Information Physical and Data-Link Standards Separate physical and data link layers for LAN and WAN Physical (bits, signals, clocking) LAN Data Link (frames) EthernetEthernet 802.3802.3 802.5802.5 FDDIFDDI 802.2 LLC

5. Connecting People To Information Physical and Data-Link Standards Separate physical and data link layers for LAN and WAN Physical (bits, signals, clocking) LAN WAN Data Link (frames) EthernetEthernet 802.3802.3 802.5802.5 FDDIFDDI 802.2 LLC X.25 Link Frame Relay ISDN PPP EIA-530 V.35 Dial on Demand SDLC HDLC V.24 HSSI G.703 EIA/TIA-232 EIA/TIA-449

6. Connecting People To Information LAN Data Link Sublayers LLC refers upward to higher-layer software functions MAC refers downward to lower-layer hardware functions Media Access Control Logical Link ControlNetworkNetwork Data Link Physical LLCLLC MAC

7. Connecting People To Information LAN Data Link Sublayers LLC refers upward to higher-layer software functions MAC refers downward to lower-layer hardware functions Media Access Control Logical Link Control NetworkNetwork Data Link Physical LLCLLC MAC Frame 802.2 LLC MAC Packet or Datagram

8. Connecting People To Information LLC Sublayer Functions Enable upper layers to gain independence over LAN media access Allow service access points (SAPs) from interface sublayers to upper-layer functions

9. Connecting People To Information Physical and Logical Addressing 0000.0c12.3456

10. Connecting People To Information MAC Address MAC address is burned into ROM on a network interface card 24 bits 0000.0c12. 3456 Vendor Code Serial Number ROM RAM

11. Connecting People To Information Finding the MAC Address Host YHost Z Query Response Example 1: Destination local Router A Example 2: Destination not local Host Z Broadcast Host Z MAC ? Host Z MAC ? Host Z Host Y MAC Host Y MAC Host Z MAC Host Z MAC Host Y Query Broadcast Host Z MAC ? Host Z MAC ? Host Z Response Host Y MAC Host Y MAC Router A MAC Router A MAC Routing Table: Net for Host Z Routing Table: Net for Host Z

12. Connecting People To Information Written Exercise: Determining MAC Addresses Host A 0000.0c12.1111 Host B 0000.0c12.2222 Host D 0000.0c12.4444 Router C 0000.0c12.3333 Router C 0000.0c12.5555 Network Y Network X

13. Common LAN Technologies

14. Connecting People To Information Ethernet Token Ring FDDI LAN Technology Overview FDDI Dual Ring

15. Connecting People To Information Ethernet and IEEE 802.3 Several framing variations exist for this common LAN technology

16. Connecting People To Information Physical Layer: Ethernet/802.3 Host 10BaseT—Twisted Pair 10Base2—Thin Ethernet 10Base5—Thick Ethernet PC Mac SunHost Hub MAC

17. Connecting People To Information The Ethernet/802.3 Interface Cisco router’s data link to Ethernet/802.3 uses an interface named E plus a number (for example, E0) 0800.2006.1a56 0000.0c12. 7c4d E0 E1 0800.890c.34d5 0000.0c12. 83e2

18. Connecting People To Information Ethernet/802.3 Operation ABCD D B and C Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical

19. Connecting People To Information Ethernet/802.3 Broadcast DCBA Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical

20. Connecting People To Information Ethernet Frame Variations Ethernet Frame 802.3 Frame Preamble DA SA Type Data FCS 86624 Preamble DA SA Length 802.2 Header and Data 802.2 Header and Data FCS 86624

21. Connecting People To Information DSAP SSAP CTRL AA CTRL OUI Ether Type Ether Type Upper Layer Data IP, AppleTalk Upper Layer Data IP, AppleTalk DATA Ethernet Frame Variations 802.3 Frame Preamble DA SA Length 802.2 Header and Data 802.2 Header and Data FCS 802.2 Frame SNAP Frame

22. Connecting People To Information Ethernet/802.3 Reliability ABCD Collision ABCD JAMJAMJAMJAMJAMJAMJAMJAMJAMJAMJAMJAM

23. Connecting People To Information High-Speed Ethernet Options 100BaseFX 100BaseT4 100BaseTX 100VG-AnyLAN

24. Common WAN Technologies

25. Connecting People To Information WAN Technology Overview SDLC HDLC LAPB PPP X.25 Frame Relay ISDN

26. Connecting People To Information Physical Layer: WAN (Modem) Data Terminal Equipment End of the user’s device on the WAN link DTE Data Circuit-Terminating Equipment End of the WAN provider’s side of the communication facility DCE EIA/TIA-232 V.35 X.21 HSSI Others CSU/DSU

27. Connecting People To Information Data Link Layer: WAN Protocols SDLC—Synchronous Data Link Control HDLC—High-Level Data Link Control LAPB—Link Access Procedure, Balanced Frame Relay—Simplified version of HDLC framing PPP—Point-to-Point Protocol X.25—Packet level protocol (PLP) ISDN—Integrated Services Digital Network (data-link signaling) (Modem) CSU/DSU (Modem)