1. Chapter 8 8/6/20151 Network Components u Two basic components to the BN u hardware devices that connect the networks to the backbone u hubs u bridges u switches u routers u brouters u gateways u network cable

2. Chapter 8 8/6/20152 Hubs u very simple devices that pass all traffic in both directions between the LAN sections they link u same or different cable types u use physical layer protocols u pass on every message u used to connect LANs of similar technology, or to extend the distance of one LAN u can be called repeaters or amplifiers

3. Chapter 8 8/6/20153 HUB Devices HUB (MAU) Repeater/Amplifier

4. Chapter 8 8/6/20154 Hubs u inexpensive u easy to Install u can connect different media u very little delay u limited distance between devices u limited on the number of repeaters u no protocol or rate conversion u no error detection u does not filter

5. Chapter 8 8/6/20155 Bridges u connect two LAN segments that use the same data link and network protocol u operated at the data link layer u same or different cable types u forward only those messages that need to go out (filtering) u “learn” whether to forward packets u internal routing table u combination of “black box” hardware and software

6. Chapter 8 8/6/20156 Bridges There are three types of bridges: u Simple bridge u Learning bridge u Multiport bridge

7. Chapter 8 8/6/20157 Bridges Interconnecting HUB (MAU) Repeater/ Amplifier HUB (MAU) Repeater/ Amplifier Bridge

8. Chapter 8 8/6/20158 Bridges u may be different data rates and different media easy to Install u no modifications required to the communications software u can learn the ports for data transmission u understand only data link layer protocols and addresses u no protocol conversion u broadcasts when it does not know the address

9. Chapter 8 8/6/20159 Switches u connect more than two LAN segments that use the same data link and network protocol. u operate at the data link layer u same or different type cable u ports are usually provided for 4, 8, 16, or 32 LAN segments u ports are used simultaneously u connect lower speed segments to high speed BN

10. Chapter 8 8/6/201510 Switches u Cut-through switches u use circuit-switching to immediately connect the port with the incoming message to the correct outgoing port u very fast as decisions are done in hardware u outgoing packet is lost if port is in use u Store-and-forward switches u copy the incoming packet to memory prior to processing the destination address -- transmit it when the outgoing port is ready

11. Chapter 8 8/6/201511 Switches Interconnecting Wing C Wing AWing B First Floor Switch

12. Chapter 8 8/6/201512 Switches u much more sophisticated than previously u enable all ports to work at the same time u can convert protocols u configurable u high speed u understand only data link layer protocols and addresses u much more expensive then previous options u higher maintenance

13. Chapter 8 8/6/201513 Routers u connect two or more LANs that use the same or different data link protocols, but the same network protocol. u same or different cable types u operate at the network layer u forward only messages that need to go out u routers use the internetwork address u internal routing tables u only processes messages addressed to it

14. Chapter 8 8/6/201514 Routers u choose the best route to send the packet (path) u IDs of other networks u paths to the networks u relative efficiency of the paths

15. Chapter 8 8/6/201515 Routers u The router must deal with network differences: u addressing schemes u minimum packet size u interfaces u reliability

16. Chapter 8 8/6/201516 \ Routers Interconnecting Router Ethernet LAN2 Token Ring LAN1 X.25 Network the “cloud”

17. Chapter 8 8/6/201517 Routers u can mix-in-match protocols and convert them u enable all ports to work at the same time u can be used as an extra layer of security u configurable u high speed u hard to configure and manage u access lists must be kept current u high maintenance/high training costs u very expensive

18. Chapter 8 8/6/201518 Brouters u devices that combine the functions of both bridges and routers u operate at both the data link and network layers u same or different data link protocol u same network protocol u as fast as bridges for same data link type networks

19. Chapter 8 8/6/201519 Gateways u complex machines that are interfaces between two or more dissimilar networks u connect two or more LANs that use the same or different data link layer, network layer, and cable types u operates at the network layer (3) or higher layers (4-7) u forwards only those messages that need to go out u a combination of both hardware and software

20. Chapter 8 8/6/201520 Gateways u translates one network protocol to another u translates data formats u translates open sessions between application programs u translates to mainframes

21. Chapter 8 8/6/201521 Gateways u Exists in four major types: u LAN-to-IBM mainframe u Network-to-network u System-to-network u System-to-system

22. Chapter 8 8/6/201522 LAN-to-IBM Mainframe u Allow LANs using TCP/IP and Ethernet to be connected to IBM mainframe using SNA u Eliminates the need for each PC on the LAN to have SNA hardware/software that makes it act like an IBM 3270 terminal Gateway Mainframe

23. Chapter 8 8/6/201523 \ Network-to-Network X.75 Gateway X.25 Network A \ X.25 Network B X.75 provides terminal address translation

24. Chapter 8 8/6/201524 System-to-Network \ X.25 Network Gateway Minicomputer or Microcomputer

25. Chapter 8 8/6/201525 System-to-System u allows connecting one vendor’s architecture to another vendor’s architecture u allows both the existence of OSI-based and proprietary architectures (like SNA or AppleTalk) u gives management to tools necessary to plan a gradual migration to a completely OSI environment u applications can work with other application

26. Chapter 8 8/6/201526 System-to-System \ X.25 Network LAN E-mail Gateway LAN E-mail Server Profs E-mail Profs E-mail Gateway

27. Chapter 8 8/6/201527 HubPhysicalAll transferredS/DSameSame BridgeData linkFiltered usingS/DSameSame data link layer add. SwitchData linkSwitched usingS/DSameSame data link layer add. RouterNetworkRouted using S/DS/DSame network layer add. BrouterData link &Filtered & routedS/DS/DSame Network GatewayNetworkRouted usingS/DS/DS/D network layer add. Physical Data Link Network DeviceOperates atMessages Layer Layer Layer Backbone Network Devices

28. Chapter 8 8/6/201528 Terminology Warnings u Multiprotocol bridges translate between different data link layer protocols. u Multiprotocol routers translate between different network layer protocols. u Protocol filtering bridges forward only packets of a certain type, i.e., token-ring or ethernet u Encapsulating bridges connect networks with different data link protocols, encapsulating messages with correct protocol for transmission u Layer-3 switches (IP switches) - can also switch messages based on their network layer address

29. Chapter 8 8/6/201529 Shared Media Technologies u Fast Ethernet u Fast Token Ring u Fiber Distributed Data Interface

30. Chapter 8 8/6/201530 Fast Ethernet u 100Base-X Ethernet u 100VG-AnyLAN u Gigabit Ethernet u Iso-ENET (isochronous ethernet)

31. Chapter 8 8/6/201531 100Base-X Ethernet u IEEE 802.13 u identical to 10Base-T Ethernet u three data link layer protocols u 100 Mbps data rate u standard ethernet bus topology u ethernet data link packets u ethernet CSMA/CD media access protocol

32. Chapter 8 8/6/201532 100Base-X Ethernet Three versions of 100Base-X Ethernet u 100Base-TX u 100Base-FX u 100Base-T4

33. Chapter 8 8/6/201533 100VG-AnyLAN u IEEE 802.12 u both Ethernet or token-ring u Demand Priority Access Method (DPAM) polling u polls each computer to see if it has data to send u can use a priority system (notification system) u four sets of twisted pair running at 25 Mbps u faster than 100Base-T

34. Chapter 8 8/6/201534 Gigabit Ethernet u IEEE 802.3Z u 1000Base-X u 1000 Mbps (1000 Mbps = 1 Gbps) u high speed of transmission may cause collisions to go undetected u mainly used for point-to-point full-duplex communication links (BN, MAN) u PCs send or receive data at rates up to 100 Mbps

35. Chapter 8 8/6/201535 Gigabit Ethernet Four versions of 1000Base-X Ethernet u 1000 Base-LX (fiber up to 440 meters) u 1000 Base-SX (fiber up to 260 meters) u 1000 Base-T (four pairs twisted-pair up to 100 meters) u 1000 Base-CX (one cat 5 cable up to 24 meters)

36. Chapter 8 8/6/201536 Iso-ENET u IEEE 802.9A u isochronous Ethernet u standard 10Base-T Ethernet + 6.144 Mbps u both transmitted on the same twisted pair u 6.144 circuit configured for ISDN for transmission of voice and video u mainly used for desktop videoconferencing and multimedia products

37. Chapter 8 8/6/201537 How much bandwidth to expect LAN TypeSpeed Ethernet10 Mbps Token Ring16 Mbps Fast Ethernet100 Mbps Faster Ethernet1 Gbps Fast Token Ring100 Mbps FDDI100 Mbps ATM2.4 Gbps Improving Circuit Capacity

38. Chapter 8 8/6/201538 Selecting a Backbone Network 5 important factors to consider: u Throughput u Network cost u Type of application u Ease of network management u Compatibility with current and future technologies