1. Network Transmission Equipment
Chapter 4

2. Learning Objectives
Describe the purpose of LAN network transmission equipment:
NICs, repeaters, MAUs, hubs, bridges, routers, brouters, switches, and gateways
Explain how LAN network equipment works
continued…

3. Learning Objectives Describe the purpose of WAN network equipment:
Multiplexers, channel banks, private telephone networks, types of modems, ISDN adapters, access servers, and routers
Explain how WAN network equipment works

4. LAN Transmission Equipment
NICs
Repeaters
MAUs
Hubs
Bridges
Routers
Brouters
Switches
Gateways

5. NIC Enables network device to connect to network
Network connection requirements
Appropriate connector for network medium
Transceiver
Controller to support MAC sublayer of Data Link layer
Protocol control firmware

6. A Combination NIC

7. Role of MAC Controller Unit
Works with firmware to correctly encapsulate:
Source and destination address information
Data to be transported
CRC error control information

8. Transport and Transmission Options
Transport options
Combined transport options make it easy to upgrade a network for high-speed communication
Transmissions options
Half-duplex transmissions
Full-duplex transmissions

9. FDDI NICs
Connect host systems/file servers to FDDI network equipment using single attachment
Attach network equipment to FDDI cabling via dual attachment

10. ATM NICs Connect ATM switches or servers to an ATM network
Available to desktop
Relatively expensive

11. Wireless NIC Modes Provide flexibility and convenience
Ad hoc peer-to-peer communication with another wireless NIC
Communication with an access point
Provide flexibility and convenience

12. Buses and NICs Industry Standard Architecture (ISA)
Extended Industry Standard Architecture (EISA)
Microchannel Architecture (MCA)
Peripheral Computer Interface (PCI)
SPARC Bus (SBUS)
NuBus
Universal Serial Bus (USB)
VESA local bus (VL-bus)

13. Choosing a NIC For host computer, server, or workstation?
Network media and network transport methods in use?
Manufacturer?
Computer or network equipment bus type?
Operating system used by the computer?
Use of half- or full-duplex communications?
How does it attach to network (for special application)?

14. Repeater
Amplifies and retimes a packet or cell-carrying signal so that it can be sent along all outgoing cable segments attached to that repeater
Filters out signal disturbance or noise

15. Repeaters Are Used to… Extend cable segment
Increase number of nodes beyond limit of one segment
Sense network problem and shut down cable segment (partitioning)
Connect to components in other network devices
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16. Repeaters Are Used to… Connect segments that use different media
Extend backbone cable segments in LANs and WANs
Extend long, fiber-optic cable segments
Increase communications distance of T-carrier lines

17. A Multiport Repeater

18. Repeaters Advantage Disadvantage Inexpensive way to extend a network
Can create excessive amount of network traffic

19. Multistation Access Unit (MAU)
Central hub that links token ring nodes into a topology that physically resembles a star but in which data signals are transferred in a logical ring pattern

20. MAUs Are Used to…
Connect workstations into a logical ring through physical star topology
Move token and frames around the ring
Amplify data signals
Connect in a daisy-chained manner to expand token ring network
Provide for orderly movement of data
Shut down ports to malfunctioning nodes

21. MAUs
Passive hub
Active hub
Patch cables and lobe cables

22. Ring In and Ring Out Ports

23. Token Ring MAU Specifications

24. Hub
Central network device used in star topology to join networks

25. Hubs Are Used to…
Provide a central unit from which to connect multiple nodes into one network
Permit many computers to be connected on single or multiple LANs
Provide multiprotocol services
Consolidate network backbone
Provide connections for different media types
Enable centralized network management and design

26. Types of Network Hubs Unmanaged hubs Dual-speed hubs Workgroup hubs
Stackable hubs
Chassis hubs

27. Bridge
Connects different LANs or LAN segments using the same access method
Operates in promiscuous mode; can look at frame addresses (unlike repeaters)
Operates at MAC sublayer of OSI Data Link layer
Protocol independent; only look at MAC address

28. Bridges Are Used to…
Extend a LAN when maximum connection limit has been reached
Extend a LAN beyond the length limit
Segment LANs to reduce data traffic bottlenecks
Prevent unauthorized access to a LAN

29. Bridged Network

30. Bridge Functions
Learning
Filtering
Forwarding

31. Cascade Bridging

32. Advantages of Bridges
Limit traffic to certain network segments; enhance performance
Can use as a firewall to keep intruders out of a network

33. Types of Bridges Local bridge Remote bridge
Connects networks in close proximity
Can be used to segment a portion of a network to reduce heavy traffic problems
Remote bridge
Joins networks across the same city, between cities, and between states to create one network

34. Bridge Token ring source-route bridge Spanning tree algorithm
Incorporated into token ring LAN specification
Performs routing at OSI Network layer
Spanning tree algorithm
Ensures that frames are not transmitted in an endless loop
Enables frames to be sent along most cost-effective network path

35. Bridge Protocol Data Units (BPDUs) Frame Format

37. Router
Connects networks having the same or different access methods and media
Forwards packets to networks by using decision-making process based on:
Routing table data
Discovery of most efficient routes
Preprogrammed information from network administrator
Connects LAN at Network layer of OSI model

39. Routers Are Used to…
Efficiently direct packets from one network to another, reducing excessive traffic
Join neighboring or distant networks
Connect dissimilar networks
Prevent network bottlenecks by isolating portions of a network
Secure portions of a network from intruders

40. Static and Dynamic Routing
Static routing
Controls routing decisions by network administrator through preset routing instructions
Dynamic routing
Constantly checks network configuration
Automatically updates routing tables
Makes decisions about how to route packets

41. Routing Tables and Protocols
Contain addresses of other routers
Routing protocols
Routing Information Protocol (RIP)
Communicates entire contents of routing tables to other routers
Open Shortest Path First (OSPF) protocol
Communicates information about immediate links to other nodes

42. Advantages of OSPF Protocol
Sends only the portion of routing table that pertains to its most immediate router links
Packages routing information in more compact format that RIP
Only updated routing table information is shared among routers, rather than the entire routing table

44. Brouter
Acts as a bridge or a router, depending on how it is set up to forward a given protocol

45. Brouters Are Used to…
Handle packets efficiently on a multiprotocol network that includes some protocols that can be routed and some that cannot
Isolate and direct network traffic to reduce congestion
Join networks
Secure a certain portion of a network by controlling who can access it

46. Switch Links network segments
Forwards and filters frames between segments
Provides bridging capacity and the ability to increase bandwidth on existing networks

47. Switching Techniques Cut-through switching
Store-and-forward switching (buffered switching)

48. Gateway
Enables communications between two different types of networked systems

49. Gateways Are Used to…
Convert commonly used protocols to a specialized protocol
Convert message formats
Translate different addressing schemes
Link a host computer to a LAN
Provide terminal emulation
Direct electronic mail to the right network destination
Connect networks with different architectures

50. Gateway

51. WAN Transmission Equipment
Designed to work over POTS and leased telephone lines (T-carrier and ISDN)
May be analog or digital
Either converts a signal for long-distance communications or creates multiple channels

52. Examples of Basic WAN Transmission Equipment
Multiplexers
Channel banks
Private telephone networks
Telephone modems
ISDN adapters
Cable TV modems
DSL modems and routers
Access servers
Routers

53. Multiplexer (MUX)
Can receive multiple inputs and transmit them to a shared network medium
Works at OSI Physical layer, switching from channel to channel using:
A single method for optical transmissions (wavelength division multiplexing or WDM), or
One of three electrical switching methods
Time division multiple access (TDMA)
Frequency division multiple access (FDMA)
Statistical multiple access

54. Using Multiplexers

55. Channel Bank
Large-scale multiplexer that combines telecommunications channels in a centralized location
First used in voice applications, now handle voice, data, and video

56. Private Telephone Networks
Private branch exchanges (PBXs)
Private automatic exchanges (PAXs)
Private automatic branch exchanges (PABXs)

57. Telephone Modems
Convert computer’s outgoing digital signal to analog signal that can be transmitted over a telephone line
Also convert incoming analog signal to a digital signal the computer can understand
Attached internally or externally

58. Telephone Modems
Types of connectors (DB-25, DB-9, PS/2, universal serial bus or USB)
Modem data transfer rate measured by baud rate or bits per second (bps)
Synchronous or asynchronous communication format

60. ISDN Adapters Connect a computer or fax to an ISDN line
Terminal adapter (TA) converts digital signal to a protocol that can be sent over a digital telephone line

61. Cable TV Modems
Digital modem devices designed for use with cable TV system, providing high-speed data transfer
Share bandwidth with others, but dynamically allocate unused cable bandwidth
Either internal or external

62. DSL Modems and Routers Digital Subscriber Line (DSL)
Uses advanced modulation technologies on existing telecommunications networks for high-speed networking between subscriber and telco
Communication speeds up to 60 Mbps
Dedicated to single user; employs full bandwidth of the line

63. Connecting to DSL

64. Access Servers
Connect synchronous and asynchronous devices to a network, providing routing for both types of communications

65. Using an Access Server

66. Remote Routers Join networks in WANs over long distances
Connect ATM, ISDN, frame relay, high-speed serial, and X.25 networks
Can support multiple protocols
Can be set up as firewalls

67. Chapter Summary
Network transmission equipment used on LANs, WANs, or both
Modems
Bridges
Gateways
Channel banks
Access servers