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Multistation Access Units (MAUs)

Multistation Access Units (MAUs). Connect workstations in a logical ring through a physical star topology Move the token and packets around the ring Amplify data signals Connect in a daisy-chained manner to expand a token ring network Provide orderly movement of data.

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Multistation Access Units (MAUs)

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  1. Multistation Access Units (MAUs) • Connect workstations in a logical ring through a physical star topology • Move the token and packets around the ring • Amplify data signals • Connect in a daisy-chained manner to expand a token ring network • Provide orderly movement of data

  2. Multistation Access Units (MAUs) • A passive hub connects nodes in a star topology, performing no signal enhance-ment as the packet moves from one node to the next through the hub. • An active hub connects nodes in a star topology, regenerating, retiming, and amplifying the data signal each time it passes through the hub.

  3. Ring-in (RI) connection Ring-out (RO) connection MAU MAU with Eight Connections

  4. Type 6 patch cable RI RO RI RO Type 6 patch cable RI RO MAUs Connected Using the RI and RO Ports

  5. To Draw the Network Diagram • Drawing the token ring network in Microsoft Paint

  6. Multiplexers • A multiplexer is a switch that divides a communication medium into multiple channels so several nodes can communicate at the same time. • A signal that is multiplexed must be demultiplexed at the other end.

  7. Multiplexers

  8. Multiplexers • Work at the OSI physical level, switching from channel to channel using one of three physical methods: • Time division multiple access (TDMA) • Frequency division multiple access (FDMA) • Statistical multiple access

  9. Multiplexers • TDMA enables multiple devices to communi-cate over the same communications medium by creating time slots in which each device transmits. • FDMA creates separate channels on one communication medium by establishing different frequencies for each channel. • Statistical multiple access multiplexing allocates the communication resources according to what is needed for the task.

  10. Repeaters • A repeater amplifies and retimes a packet-carrying signal so it can be sent along all cable segments. • As used in this context, a segment of cable is one cable run within the IEEE specifications.

  11. How Repeaters Are Used • To extend a cable segment • To increase the number of nodes beyond the limit of one segment • To sense a problem and shut down a cable segment • To amplify and retime a signal (as a component in other network devices)

  12. Research lab Research lab Repeater President’s office Business office Using a Repeaterto Extend a Network

  13. Repeaters • An attached unit interface (AUI) connects coax or fiber-optic backbone cable to a network node, such as a repeater. • A partitioned segment is one that has been shut down because a portion of the segment is malfunctioning.

  14. To Diagram the Interoffice Network • Microsoft Paint diagram of two rooms connected by a repeater

  15. Bridges • A bridge is a network device that connects different LAN segments using the same access method.

  16. How Bridges Are Used • To extend a LAN when the maximum connection limit has been reached • To extend a LAN beyond the length limit • To segment LANs to reduce data traffic bottlenecks • To prevent unauthorized access to LAN (for security)

  17. Bridge Bridged Network

  18. Bridges • A network device that operates in promiscuous mode reads frame destination address information before sending a packet onto other connected segments of the network.

  19. Types of Bridges • A local bridge connects networks in close proximity and is used to segment a portion of a network to reduce problems caused by heavy traffic. • A remote bridge joins networks across the same city, between cities, and between states to create one network.

  20. Important Functions of a Bridge • Learning • Filtering • Forwarding

  21. LAN 1 Bridge A LAN 2 Bridge B LAN 3 Cascaded Network Segments

  22. Token Ring Bridging • Token ring bridges use source routing to forward packets on the network. • Hops are the number of times a packet travels point-to-point from one network to the next. Source route bridging

  23. Routers • A router connects networks having the same or different access methods. • It forwards packets to networks by using a decision-making process based on: • Routing table data • Discovery of the most efficient routes • Preprogrammed information from the network administrator

  24. How Routers Are Used • To efficiently direct packets from one network to another, reducing excessive traffic • To join neighboring or distant networks • To connect dissimilar networks • To prevent network bottlenecks by isolating portions of a network • To secure portions of a network from intruders

  25. A Router Forwarding a Frame to the Right Network

  26. Static and Dynamic Routing • Static routing involves control of routing decisions by the network administrator through preset routing instructions. • In dynamic routing, the router constantly: • Checks the network configuration • Automatically updates routing tables • Makes its own decisions about how to route frames

  27. Routing Tables and Protocols • Routers maintain information about node addresses and network status in databases. • The routing table database contains the addresses of other routers and each end node. • Routers regularly exchange information about network traffic, the network topology, and the status of network lines. • Routers exchange information by using one or more routing protocols.

  28. Local and Remote Routers • A local router joins networks in the same building or between buildings in close proximity. • A firewall is software and/or hardware employed to restrict who has access to a network, to specific network segments, or to certain network resources (such as servers). • A remote router joins networks across large geographical areas, such as between cities, states, and countries.

  29. A Local Router Connecting Networks in Adjacent Buildings Business building Manufacturing building Router

  30. Brouters • A brouter, also called a multiprotocol router, is a network device that acts like a bridge or a router, depending on how it is set up to forward a given protocol. • It is used on networks that operate with several different protocols.

  31. How Brouters Are Used • For efficient packet handling on a multiprotocol network with some protocols that can be routed and some that cannot • To isolate and direct network traffic to reduce congestion • To join networks • To secure a certain portion of a network by controlling who can access it

  32. Hubs • A hub is a central network device that connects network devices in a star topology. • It is also referred to as a concentrator (or switch), which is a device that can have multiple inputs and outputs all active at one time.

  33. Services Offered by Hubs • Provide a central unit from which to connect multiple nodes into one network • Permit large numbers of computers to be connected on single or multiple LANs • Reduce network congestion through centralizing network design • Provide multiprotocol services

  34. Types of Hubs • MAUs • 10BASE-T hubs • 100BASE-X hubs • Intelligent and modular hubs

  35. 10BASE-T Hubs • One of the simplest hubs • Popular way to connect workgroups on small and large LANs • Uses physical star topology to connect PCs to the central hub • Additional hubs are added by connecting one hub to the next.

  36. Switching Hubs • Permit significant increase in the throughput capability of an existing 4 Mbps, 10 Mbps, or 16 Mbps network by taking full advantage of exiting bandwidth capabilities • Allow an existing network to be separated into multiple smaller segments, each independent of the others • Can be installed on LANs in a WAN where specific LANs are experiencing increased network traffic

  37. 100BASE-X Hubs • Multimedia, video, and GUI client/server applications have fostered the need for high-bandwidth, high-speed technologies.

  38. Intelligent and Modular Hubs • An intelligent hub has network management and performance monitoring capabilities. • A modular hub, also called a chassis hub, contains a backplane into which different modules can be inserted. • A backplane is the main circuit board in modular equipment, containing slots as plug-ins for modular cards. It provides connections between the modular boards, a power source, and grounding.

  39. To Diagram 10BASE-T Star Topology on Two Floors • Network diagram of 10BASE-T network segments connected to an intelligent hub

  40. Gateways • A gateway enables communications between two different types of networked systems, such as between complex protocols or between different e-mail systems.

  41. How Gateways Are Used • To convert commonly used protocols to a specialized protocol • To convert message formats from one format to another • To translate different addressing schemes • To link a host computer to a LAN continued

  42. How Gateways Are Used • To provide terminal emulation for connections to a host computer • To direct e-mail to the right network destination • To connect networks with different architectures

  43. Systems Network Architecture (SNA) • SNA is a layered communications protocol used by IBM for communications between IBM mainframe computers and terminals. • It employs seven-layered communications that are similar to the OSI model, but there are differences in the way the services are grouped within the layers.

  44. SNA gateway IBM/Mainframe Connected through an SNA Gateway

  45. ATM Switches • An ATM switch determines the network channel used to transmit an ATM cell received from a node, taking into account the type of information in the cell (voice, video, data) and the transmission speed needed.

  46. Capabilities of ATM Switches • Provide high-speed communications on a network backbone • Provide cell transmissions directly to the desktop • Enable high-speed communication between network hubs • Centralize network design for better management continued

  47. Capabilities of ATM Switches • Connect to very high speed networks, such as SONET • Enable network design around workgroup members at dissimilar locations (virtual LANs) • Reduce network bottlenecks through high-speed communications and efficient traffic management through workgroups

  48. ATM switch ATM Switch

  49. Virtual LANs (VLANs) • A virtual LAN (VLAN) uses switches, routers, and internetworking software to configure a network into subnetworks of logical workgroups, independent of the physical network topology.

  50. Advantages of VLANs • VLANs enable a network to operate at the most efficient level; it is not limited by physical topology. • Network resources can be managed based on the actual work groupings of users. • VLANs can be reconfigured to move a user from an old workgroup to new one.

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