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Network Components

Network Components. Two basic components to the BN hardware devices that connect the networks to the backbone hubs bridges switches routers brouters gateways network cable. Hubs. very simple devices that pass all traffic in both directions between the LAN sections they link

dawn-puckett
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Network Components

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  1. Network Components • Two basic components to the BN • hardware devices that connect the networks to the backbone • hubs • bridges • switches • routers • brouters • gateways • network cable

  2. Hubs • very simple devices that pass all traffic in both directions between the LAN sections they link • same or different cable types • use physical layer protocols • pass on every message • used to connect LANs of similar technology, or to extend the distance of one LAN • can be called repeaters or amplifiers

  3. HUB Devices Repeater/Amplifier HUB (MAU)

  4. Hubs • inexpensive • easy to Install • can connect different media • very little delay • limited distance between devices • limited on the number of repeaters • no protocol or rate conversion • no error detection • does not filter

  5. Bridges • connect two LAN segments that use the same data link and network protocol • operated at the data link layer • same or different cable types • forward only those messages that need to go out (filtering) • “learn” whether to forward packets • internal routing table • combination of “black box” hardware and software

  6. Bridges There are three types of bridges: • Simple bridge • Learning bridge • Multiport bridge

  7. Repeater/ Amplifier Repeater/ Amplifier HUB (MAU) HUB (MAU) Bridges Interconnecting Bridge

  8. Bridges • may be different data rates and different media easy to Install • no modifications required to the communications software • can learn the ports for data transmission • understand only data link layer protocols and addresses • no protocol conversion • broadcasts when it does not know the address

  9. Switches • connect more than two LAN segments that use the same data link and network protocol. • operate at the data link layer • same or different type cable • ports are usually provided for 4, 8, 16, or 32 LAN segments • ports are used simultaneously • connect lower speed segments to high speed BN

  10. Switches • Cut-through switches • use circuit-switching to immediately connect the port with the incoming message to the correct outgoing port • very fast as decisions are done in hardware • outgoing packet is lost if port is in use • Store-and-forward switches • copy the incoming packet to memory prior to processing the destination address -- transmit it when the outgoing port is ready

  11. Wing A Wing B First Floor Switch Wing C Wing C Switches Interconnecting

  12. Switches • much more sophisticated than previously • enable all ports to work at the same time • can convert protocols • configurable • high speed • understand only data link layer protocols and addresses • much more expensive then previous options • higher maintenance

  13. Routers • connect two or more LANs that use the same or different data link protocols, but the same network protocol. • same or different cable types • operate at the network layer • forward only messages that need to go out • routers use the internetwork address • internal routing tables • only processes messages addressed to it

  14. Routers • choose the best route to send the packet (path) • IDs of other networks • paths to the networks • relative efficiency of the paths

  15. Routers • The router must deal with network differences: • addressing schemes • minimum packet size • interfaces • reliability

  16. Routers Interconnecting Router \ Ethernet LAN2 X.25 Network the “cloud” Token Ring LAN1

  17. Routers • can mix-in-match protocols and convert them • enable all ports to work at the same time • can be used as an extra layer of security • configurable • high speed • hard to configure and manage • access lists must be kept current • high maintenance/high training costs • very expensive

  18. Brouters • devices that combine the functions of both bridges and routers • operate at both the data link and network layers • same or different data link protocol • same network protocol • as fast as bridges for same data link type networks

  19. Gateways • complex machines that are interfaces between two or more dissimilar networks • connect two or more LANs that use the same or different data link layer, network layer, and cable types • operates at the network layer (3) or higher layers (4-7) • forwards only those messages that need to go out • a combination of both hardware and software

  20. Gateways • translates one network protocol to another • translates data formats • translates open sessions between application programs • translates to mainframes

  21. Gateways • Exists in four major types: • LAN-to-IBM mainframe • Network-to-network • System-to-network • System-to-system

  22. LAN-to-IBM Mainframe • Allow LANs using TCP/IP and Ethernet to be connected to IBM mainframe using SNA • Eliminates the need for each PC on the LAN to have SNA hardware/software that makes it act like an IBM 3270 terminal Mainframe Gateway

  23. Network-to-Network \ X.25 Network A X.75 Gateway \ X.25 Network B X.75 provides terminal address translation

  24. System-to-Network \ X.25 Network Gateway Minicomputer or Microcomputer

  25. System-to-System • allows connecting one vendor’s architecture to another vendor’s architecture • allows both the existence of OSI-based and proprietary architectures (like SNA or AppleTalk) • gives management to tools necessary to plan a gradual migration to a completely OSI environment • applications can work with other application

  26. System-to-System Profs E-mail Gateway \ X.25 Network LAN E-mail Server Profs E-mail LAN E-mail Gateway

  27. Backbone Network Devices Physical Data Link Network Device Operates at Messages Layer Layer Layer Hub Physical All transferred S/D Same Same Bridge Data link Filtered using S/D Same Same data link layer add. Switch Data link Switched using S/D Same Same data link layer add. Router Network Routed using S/D S/D Same network layer add. Brouter Data link & Filtered & routed S/D S/D Same Network Gateway Network Routed using S/D S/D S/D network layer add.

  28. Terminology Warnings • Multiprotocol bridges translate between different data link layer protocols. • Multiprotocol routers translate between different network layer protocols. • Protocol filtering bridges forward only packets of a certain type, i.e., token-ring or ethernet • Encapsulating bridges connect networks with different data link protocols, encapsulating messages with correct protocol for transmission • Layer-3 switches (IP switches) - can also switch messages based on their network layer address

  29. Shared Media Technologies • Fast Ethernet • Fast Token Ring • Fiber Distributed Data Interface

  30. Fast Ethernet • 100Base-X Ethernet • 100VG-AnyLAN • Gigabit Ethernet • Iso-ENET (isochronous ethernet)

  31. 100Base-X Ethernet • IEEE 802.13 • identical to 10Base-T Ethernet • three data link layer protocols • 100 Mbps data rate • standard ethernet bus topology • ethernet data link packets • ethernet CSMA/CD media access protocol

  32. 100Base-X Ethernet Three versions of 100Base-X Ethernet • 100Base-TX • 100Base-FX • 100Base-T4

  33. 100VG-AnyLAN • IEEE 802.12 • both Ethernet or token-ring • Demand Priority Access Method (DPAM) polling • polls each computer to see if it has data to send • can use a priority system (notification system) • four sets of twisted pair running at 25 Mbps • faster than 100Base-T

  34. Gigabit Ethernet • IEEE 802.3Z • 1000Base-X • 1000 Mbps (1000 Mbps = 1 Gbps) • high speed of transmission may cause collisions to go undetected • mainly used for point-to-point full-duplex communication links (BN, MAN) • PCs send or receive data at rates up to 100 Mbps

  35. Gigabit Ethernet Four versions of 1000Base-X Ethernet • 1000 Base-LX (fiber up to 440 meters) • 1000 Base-SX (fiber up to 260 meters) • 1000 Base-T (four pairs twisted-pair up to 100 meters) • 1000 Base-CX (one cat 5 cable up to 24 meters)

  36. Iso-ENET • IEEE 802.9A • isochronous Ethernet • standard 10Base-T Ethernet + 6.144 Mbps • both transmitted on the same twisted pair • 6.144 circuit configured for ISDN for transmission of voice and video • mainly used for desktop videoconferencing and multimedia products

  37. Improving Circuit Capacity How much bandwidth to expect LAN Type Speed Ethernet 10 Mbps Token Ring 16 Mbps Fast Ethernet 100 Mbps Faster Ethernet 1 Gbps Fast Token Ring 100 Mbps FDDI 100 Mbps ATM 2.4 Gbps

  38. Selecting a Backbone Network 5 important factors to consider: • Throughput • Network cost • Type of application • Ease of network management • Compatibility with current and future technologies

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