Đang tải... (xem toàn văn)
Students will be able to:Explain how physical layer protocols and services support communications across data networks.Build a simple network using the appropriate.Explain the role of the data link layer in supporting communications across data networks.Compare media access control techniques and logical topologies used in networks
Chapter 3: Network Access Introduction to Networks Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Chapter 3: Objectives Students will be able to: Explain how physical layer protocols and services support communications across data networks Presentation_ID Build a simple network using the appropriate Explain the role of the data link layer in supporting communications across data networks Compare media access control techniques and logical topologies used in networks © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Chapter 3.1 Physical Layer Protocols 3.2 Network Media 3.3 Data Link Layer Protocols 3.4 Media Access Control 3.5 Summary Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Getting it Connected Connecting to the Network Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Getting it Connected Connecting to the Network Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Getting it Connected Network Interface Cards Connecting to the Wireless LAN with a Range Extender Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Purpose of the Physical Layer The Physical Layer Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Purpose of the Physical Layer Physical Layer Media Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Purpose of the Physical Layer Physical Layer Standards Standard organization Presentation_ID Networking Standards ISO • • EIA/TIA • • • • ISO 8877: Officially adopted the RJ connectors (e.g., RJ-11, RJ-45) ISO 11801: Network cabling standard similar to EIA/TIA 568 TIA-568-C: Telecommunications cabling standards, used by nearly all voice, video and data networks TIA-569-B: Commercial Building Standards for Telecommunications Pathways and Spaces TIA-598-C: Fiber optic color coding TIA-942: Telecommunications Infrastructure Standard for Data Centers ANSI • 568-C: RJ-45 pinouts Co-developed with EIA/TIA ITU-T • G.992: ADSL IEEE • • • 802.3: Ethernet 802.11: Wireless LAN (WLAN) & Mesh (Wi-Fi certification) 802.15: Bluetooth © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Fundamental Principles of Layer Physical Layer Fundamental Principles Media Copper cable Fiber Optic cable Wireless media Presentation_ID Physical Components Frame Encoding Technique Signalling Method • • • • • • • • • • • • • • • • • • • • • • • UTP Coaxial Connectors NICs Ports Interfaces Single-mode Fiber Multimode Fiber Manchester Encoding Non-Return to Zero (NRZ) techniques 4B/5B codes are used with Multi-Level Transition Level Changes in the electromagnetic field Intensity of the electromagnetic field Phase of the electromagnetic wave (MLT-3) signaling • • • • 8B/10B PAM5 Wavelength multiplexing using different colors • • DSSS (direct-sequence spread-spectrum) • Pulses of light A pulse equals No pulse is Connectors NICs Interfaces Lasers and LEDs Photoreceptors Access Points NICs • • Radio waves OFDM (orthogonal frequency division multiplexing) Radio Antennae © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 10 LAN Topologies Logical Topology for Shared Media Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 51 LAN Topologies Contention-Based Access Presentation_ID Characteristics Contention-Based Technologies • • • • • Stations can transmit at any time Collision exist CSMA/CD for 802.3 Ethernet networks CSMA/CA for 802.11 wireless networks There are mechanisms to resolve contention for the media © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 52 LAN Topologies Multi-Access Topology Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 53 LAN Topologies Controlled Access Presentation_ID Characteristics Controlled Access Technologies • • • • • • Only one station can transmit at a time Devices wishing to transmit must wait their turn Token Ring (IEEE 802.5) Fiber Distributed Data Interface (FDDI) No collisions May use a token passing method © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 54 LAN Topologies Ring Topology Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 55 Data Link Frame The Frame Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 56 Data Link Frame The Header Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 57 Data Link Frame Layer Address Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 58 Data Link Frame The Trailer Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 59 Data Link Frame LAN and WAN Frames Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 60 Data Link Frame Ethernet Frame Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 61 Data Link Frame Point-to-Point Protocol Frame Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 62 Data Link Frame 802.11 Wireless Frame Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 63 Network Access Summary • Physical Layer Protocols • Network Media • Data Link Layer Protocols • Media Access Control Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 64 Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential 65 ... in networks © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Chapter 3.1 Physical Layer Protocols 3.2 Network Media 3.3 Data Link Layer Protocols 3.4 Media Access Control 3.5 ... data networks Presentation_ID Build a simple network using the appropriate Explain the role of the data link layer in supporting communications across data networks Compare media access. .. it Connected Connecting to the Network Presentation_ID © 2008 Cisco Systems, Inc All rights reserved Cisco Confidential Getting it Connected Connecting to the Network Presentation_ID © 2008 Cisco