Chapter 4: The Medium Access Sublayer

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Chapter 4 The Medium Access Sublayer
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Learning Objectives

• Explain IEEE 802.3 (Ethernet) network data
  transport and media specifications
• Explain IEEE 802.5 (Token Ring) network data
  transport and media specifications
• Describe Microsoft networking services and
  protocol support, including NetBIOS, NetBEUI,
  NDIS, and ODI

continued
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Learning Objectives

• Explain the IPX/SPX and NWLink protocols
• Explain the TCP/IP protocol

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Ethernet Transport System

• Uses the Carrier Sense Multiple Access with
  Collision Detection (CSMA/CD) access method for
  data transmission on a network
• Regulates transmission by sensing the presence of
  packet collisions
• Typically implemented in a bus or star topology

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Characteristics of Ethernet Communications

• No central control governs data transmission.
• The network can be accessed from many points and
  all nodes have equal ability to transmit on the
  network.
• Data units are transmitted as encapsulated
  frames.
• Each transmitted frame contains addresses of the
  sending and receiving nodes.

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Characteristics of Ethernet Communications

• Frame addressing includes the ability to specify
  one node, multiple nodes, or all nodes on the
  network.
• The packets reach every network node.
• It is the responsibility of the receiving node to
  recognize and accept frames with its address as
  its destination.
• Data transmission is relatively fast.

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Characteristics of Ethernet Communications

• Efficient error detection keeps transmission
  delays to a minimum.
• The communication specification discourages
  implementation of features that might lead to
  incompatible network variations.

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The IEEE 802.3 Standards
The 802.3 packet format
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Ethernet II

• An Ethernet frame-formatting method used on the
  Internet and other modern networks

The Ethernet II packet format
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Signal Transmission
One Ethernet node transmitting
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Signal Transmission Definitions

• Carrier sense is the process of checking a
  communication medium, such as cable, for a
  specific voltage or signal level that indicates
  the presence of a data-carrying signal.
• A collision occurs when two or more packets are
  detected at the same time on an Ethernet network.

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Network Addressing

• Ethernet addressing is accomplished through the
  OSI MAC (media access control) sublayer within
  the data link layer.
• The MAC sublayer uses an address associated with
  the NIC to direct encapsulated data to the data
  link layer of the receiving node.

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Ethernet Physical Layer Media

• A driver is software that enables a computer to
  communicate with other devices.

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Connection via a NIC
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Token Ring Transport System

• Remains a primary LAN technology
• Uses a physical star topology but with the logic
  of a ring topology to pass a token from node to
  node

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Multistation Access Unit

• A multistation access unit (MAU) is a central hub
  that links token ring nodes into a topology that
  physically resembles a star but in which packets
  are transferred in a logical ring pattern.

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Multistation Access Unit
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IEEE 802.5 Standards
The 802.5 frame format
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Error Determination Through Beaconing

• Beaconing is the error condition on a token ring
  network that indicates one or more nodes is not
  functioning.

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Microsoft Networking Services
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Microsoft Networking Services
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NetBIOS and NetBEUI

• Network Basic Input/Output System (NetBIOS) is a
  combination software interface and network-naming
  convention. It is well suited for small LANs
  using Microsoft or IBM operating systems.
• NetBIOS Extended User Interface (NetBEUI) is a
  protocol that incorporates NetBIOS for
  communications across a network.

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NetBIOS/NetBEUI Communications
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To Give Your Computer a Network Name

• Entering a workstation name

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To Set Up the NetBEUI Protocol for Windows 98

• Setting up a protocol

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To Set Up the NetBEUI Protocol for Windows 98

• Selecting the NetBEUI as the protocol

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To Configure a NICin Windows 98

• Selecting a NIC

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To Configure a NICin Windows 98

• Entering the driver type

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To Configure a NICin Windows 98

• Setting the network bindings

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NDIS

• The Network Driver Interface Specification (NDIS)
  is a software driver specification that enables
  Microsoft network protocols to communicate with a
  NIC.

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ODI

• The Open Datalink Interface (ODI) driver is used
  by Novell NetWare networks to transport multiple
  protocols on multiple networks.

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IPX and NWLink

• Xerox Network System (XNS) is a protocol
  developed by Xerox for Ethernet communications.
• Internet Packet Exchange (IPX) is a protocol
  developed by Novell for use with its NetWare file
  server operating system.

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IPX and NWLink

• Sequence Packet Exchange (SPX) is a Novell
  protocol used for network transport when there is
  a particular need for data reliability.
• NWLink is a network protocol that simulates the
  IPX/SPX protocol for Microsoft Windows 95 and NT
  communications with Novell NetWare file servers
  and compatible drivers.

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To Install NetWare Client Service

• Setting up a client for NetWare Networks
• Installing Client Service for NetWare in Windows
  NT 4.0

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TCP/IP

• Transmission Control Protocol/Internet Protocol
  (TCP/IP) is a protocol particularly well suited
  for medium and large networks.
• TCP performs extensive error checking to ensure
  that data is delivered successfully
• IP consists of rules for packaging data and for
  ensuring it reaches the correct destination
  address

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TCP/IP

• A terminal is a device consisting of a monitor
  and a keyboard to communicate with a host
  computer that runs programs. It does not have a
  processor to use for running programs locally.

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TCP/IP

• Static addressing is an IP addressing method that
  requires the network administrator to manually
  assign and set up a unique network address on
  each workstation connected to a network.
• Dynamic addressing is a method in which an IP
  address is assigned to a workstation without the
  need for the network administrator to hard-code
  it in the workstations network setup.

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TCP/IP

• Dynamic Host Configuration Protocol (DHCP)
  provides a way for a server to automatically
  assign an IP address to a workstation on its
  network.
• The Windows Internet Naming Service (WINS)
  enables the server to convert workstation names
  to IP addresses for Internet communications.

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TCP/IP

• A subnet mask is a method to show which part of
  the IP address uniquely identifies the network
  and which part uniquely identifies the
  workstation.

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To Install the TCP/IP Protocol on a Windows NT
Computer

• Indicating if there is a DHCP server
• Accessing the TCP/IP protocol properties

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To Install the TCP/IP Protocol on a Windows NT
Computer

• Entering the IP address and subnet mask

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Advantages of TCP/IP

• Well suited for medium to large networks and
  enterprise networks
• Designed for routing and has a high degree of
  reliability
• Used worldwide for directly connecting to the
  Internet by Web servers
• Compatible with standard tools for analyzing
  network performance
• Parallel ability to use DHCP and WINS through a
  Microsoft NT server

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Disadvantages of TCP/IP

• More difficult to set up and maintain than
  NetBEUI or IPX/SPX
• Somewhat slower than IPX/SPX and NetBEUI on
  networks with light to medium traffic volume

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Protocols Associated with TCP/IP

• Telnet
• File Transfer Protocol (FTP)
• Simple Mail Transfer Protocol (SMTP)
• Domain Name Service (DNS)

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Protocols Associated with TCP/IP

• Telnet is a TCP/IP application protocol that
  provides terminal-emulation services.
• The file transfer protocol (FTP) is an
  application protocol used to transfer data files
  from one computer system to another.
• The network file system (NFS) is a UNIX-based
  network file transfer protocol that ships files
  as streams of records.

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Protocols Associated with TCP/IP

• Simple Mail Transfer Protocol (SMTP) is an e-mail
  protocol used by systems having TCP/IP network
  communications.
• A domain name service (DNS) is a TCP/IP
  application protocol that translates domain
  computer names to IP addresses or IP to addresses
  to domain names.

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