Networking 101

1. Networking 101 Michael Hussein Technology Group, Inc St. Joseph Hospital and Medical Center College Station, Texas

2. Overview Introduction Topologies Network Transports Internetworking TCP/IP and the Internet Security Emerging Technologies

3. Definition Through a combination of hardware and software, networks permit information and peripherals to be shared efficiently and economically.

4. History • Early years of computing: • provided electronic mail (e-mail), word processing, database, and simple messaging. • allowed users to share data.

5. Point-to-point connections Terminals Host computer Host to Terminal Connections

6. History • Personal Computers (PCs): • brought mainframe applications to the desktop. • gained terminal emulation, word processing, and database applications. • could not share data, or send and receive e-mail. • one printer, modem per PC (very expensive). • Networks: • have the capabilities of the mainframe distributed among PCs.

7. Network cable plant Workstation Host computer Virtual connection to the host Workstation to file server File server PC LAN with Host Connection

8. OSI Model • Developed by the International Organization for Standardization in 1974 • It consists of seven layers. • Each layer has a different but specific processing function. • Each layer provides functions for the layer directly adjacent to it. • Modules (layers) may be replaced with one of equal type (that is, transport layer may not be replaced with the network layer).

9. OSI layer Function provided Network applications such as file transfer and terminal emulation Application Data formatting and encryption Presentation Establishment and maintenance of sessions Session Provision for end-to-end reliable and unreliable delivery Transport Delivery of packets of information, which includes routing Network Transfer of units of information, framing, and error checking Data Link Transmission of binary data of a medium Physical OSI Model Layers

10. Overview Introduction Topologies Network Transports Internetworking TCP/IP and the Internet Security Emerging Technologies

11. Network Topologies • Topologies are the architectural “drawings” that show the overall physical configuration for a given communications system. • A topology will indicate the access methods and will govern the rules that are used to design and implement the communication system. • Topologies represent the drawing of your network cable plant. • There are three main types of network topologies: star, ring, and bus.

12. Network Topologies • Linear Bus - Ethernet/IEEE 802.3 10Base2 and 10Base5 • Star Wired Ring - Token Ring/IEEE 802.5 • Star Wired Bus - Ethernet/IEEE 802.3i 10BaseT • Dual Counter Rotating Ring - FDDI/ANSI X3T9.5 • Wireless - Product Specific

13. Central Hub Star Topology Node Node Node Node

14. Node Data direction Transmitter Receiver Node Node Repeater Node Ring Topology

15. Bus Topology Node Node Node

16. Star-Wired Bus Topology Node Node Node Node Node Node Concentrator Hub

17. Physical Media • Physical media provide the connections between network devices that make internetworking possible. • There are four main types of physical media in widespread use today: • Coaxial Cable • Twisted Pair • Fiber Optic Cable • Wireless Media

18. Thick Coaxial Cable • Used in the first ethernet networks • Type RG-11 / 10Base5 • Usually bright yellow • Thickness of a garden hose

19. Thin Coaxial Cable • Alternative to Thick Ethernet Cable • Type RG-58 / 10Base2 / “Cheapnet” • Usually black • Thickness of a pencil • More flexible than thick ethernet

20. Twisted Pair Cable • Twisted Pair Cable consists of two copper wires, usually twisted around each other to help cancel out any induce noise in the circuit. • Two main type of Twisted Pair Cabling • Shielded Twisted Pair (STP) • Unshielded Twisted Pair (UTP)

21. STP • Shielded twisted pair is the original media used for token ring networks. • STP can be used for high-speed networks, such as FDDI or ATM, where shielding is important.

22. UTP • Most commonly used twisted pair cable. • UTP was standardized by the IEEE 802.3 committee in October of 1990. • UTP for LANs is now classified as: • Category 3 - used for LANs up to 10 Mbps • Category 4 - used for LANs up to 16Mbps • Category 5 - used for LANs up to 100Mbps • Cable is made up of 8 strands of 24 AWG wire.

23. Fiber Optic Cable • Fiber optic cable uses light signals transmitted over a very thin filament, usually made of glass. • Advantage over other types of media in regard to security against eavesdropping, immunity to interference, and maximum length of a single segment. • Most expensive of all media.

24. Wireless Media • A number of wireless media are used in internetworking, e.g.: • Microwave • Radio wave • Infrared signaling

25. Concentrators/Hubs Repeater cards slide into chassis. Cards interconnect through a common backplane. 10BASE2 module Connection for thick coaxial cable Wiring concentrator chassis 10BASET module Fiber module

26. Concentrators/Hubs 10BASET Fiber 10BASE2

27. Overview Introduction Topologies Network Transports Internetworking TCP/IP and the Internet Security Emerging Technologies

28. Network Transports • Ethernet / Fast Ethernet / IEEE 802.3 • Token Ring / IEEE 802.5 • FDDI / FDDI/ANSI X3T9.5

29. Ethernet Cable Names Name Thick coaxial Thin coaxial Unshielded Twisted Pair Fiber RG-8 Wire Type 22 - 26 AWG 62.5/125 micron RG-58 10BASE5 10BASE2 10BASEF 10BASET IEEE Name N/A Standard Number IEEE 802.3 IEEE 802.3a IEEE 802.3i Other names Thick net Thin net UTP

30. How Ethernet Works • An access method based on the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) algorithm. • Cooperative effort between Digital, Intel, and Xerox produced Ethernet version 1.0 in 1980. • Ethernet was adopted with modifications by the standards committees IEEE 802.3 and ANSI 8802/3. • Most widely used network system today.

31. Normal Ethernet Operation B C Address mismatch packet discarded Address mismatch packet discarded Send data to node D Address match packet processed Transmitted packet seen by all stations on the LAN (broadcast medium) A D Data

32. CSMA/CD • Ethernet uses the Carrier Sense Multiple Access with Collision Detection algorithm. • A network station wishing to transmit will first check the cable plant to ensure that no other station is currently transmitting (CARRIER SENSE) • The communications medium is one cable, therefore, it does not allow multiple stations access to it with all being able to transmit and receive on the same cable (MULTIPLE ACCESS)

33. CSMA/CD • Ethernet detection is implemented throughout the use of a station “listening” while it is transmitting data. • Many ways to detect when another station has erroneously started to transmit. • Two or more stations transmitting causes a collision (COLLISION DETECTION). • A jam signal is transmitted to the network by the transmitting stations that detected the collision, to ensure that all stations know of the collision. All stations will “backoff” for a random time. • Detection and retransmission is accomplished in microseconds.

34. Ethernet Collisions B C Collision Data transmission for C Data transmission for A A D

35. Ethernet at 100Mbits/sec • With the increasing use of multimedia, video, CAD, etc. - there is an increasing need for higher bandwidth to the desktop. • There are two new Ethernet standards that run at 100Mbits/sec. • 100VG-AnyLAN / IEEE 802.12 • 100Base-X / IEEE 802.3

36. 100Base-X / Fast Ethernet • Supports 100 Mbits/sec • Uses the same CSMA/CD access method. • Category 5 twisted-pair data-grade wiring is required to support the high data rate. • Topology is a star-configuration similar to Ethernet 10Base-T with all wires leading to a central concentrator (hub device).

37. Gigabit Ethernet • IEEE 802.3 committee study group examining the feasibility of gigabit ethernet. • IEEE 802.12 (VG-AnyLan group) are also studying the possibilities of gigabit ethernet. • Will initially be offered over a fiber channel interface - not Cat 5 ethernet wiring.

38. Final Ethernet Issues • Ethernet is an access method that strictly adheres to the CSMA/CD algorithm. • Ethernet is a multiprotocol solution. • Ethernet is hardware, not software.

39. Token Ring • The Token Ring topology combines the physical star and logical ring and is known as the star-wired ring. • IBM officially announced 4Mbit/s Token Ring in October 1985. • Token Ring conforms to the IEEE 802.5 standard. • Also available in 16Mbit/s version

40. Token Ring:Cabling/Topology • Token ring networks normally use twisted-pair cable, shielded or unshielded. • All wiring is concentrated at a common point known as the Multistation Access Unit (MAU)

41. How Token Ring Works • Token Ring controls which PC can send messages by passing a token from station to station around the ring. • When a PC wants to transmit it will replace the token with a “frame” (message). • The frame is passed from PC to PC until it reaches its destination.

42. How Token Ring works • The destination PC makes a copy of the “frame” (message) and marks the frame to indicate that it got the message. • The frame circulates around the network until it gets back to the sender. • The sender, seeing that the message has been received, replaces it with a new token.

43. Fiber Data Distributed Interface (FDDI) • Fiber-Optic cable standard developed by the ANSI X3T9.5 committee. • Operates at 100 Mbits/sec and uses a dual-ring topology that supports 500 nodes over a maximum distance of 100 kilometers (60 miles). • FDDI is mainly a “backbone” technology.

44. FDDI Cabling and Topology • An FDDI ring actually comprises primary and secondary rings. • In normal operation data only travels on the primary ring. • In the event of a fault, wrapping causes the primary and secondary rings to combine. • The primary cable that is used is fiber optic. • Copper cable has been approved for FDDI (only on CAT 5 wire).

45. FDDI - How it works • FDDI uses a token-passing access method. • Network stations must wait for the Token before transmitting. • A network station will capture the Token and transmits a “frame” to the ring. • The station may transmit as many frames as it can until a timer expires. • The frame is passed along the ring until it reaches its destination.

46. FDDI - How it works • The destination station copies the frame and repeats it to the ring. • The originating station strips the frame from the ring when it returns.

47. Final FDDI Issues • FDDI is a “sunset” technology. • 100BaseFX is much less expensive • No latency in 10BaseT to 100BaseT as opposed to the FDDI / 10BaseT

48. Ethernet, Token Ring, FDDI • FDDI IEEE 802.3 IEEE 802.5 • Bandwidth 100 Mbps 10 Mbps 4 or 16 Mbps • Number of stations 500 1024 250 • Maximum distance • between stations 2 km (1.2 mi) 2.8 km (1.7 mi) 300 m (984 ft) station to • with MMF wiring closet (4 Mbps); • 20 km (12.4 mi) recommended standard • with SMF is 100 m (330 ft) for 16/4 Mbps • Maximum network extent 100 km (62 miles) 2.8 km 300 / 100 m • Logical topology Dual ring, dual ring Bus Single ring • of trees • Physical topology Ring, Star, Star, bus Ring, star • Hierarchical star Hierarchical star Hierarchical star • Media Optical fiber Optical fiber Shielded or unshielded twisted pair • Unshielded twisted pair Optical fiber • Coaxial Cable • Access method Timed token passing CSMA/CD Token passing • Token acquisition Captures the token N/A Sets a bit converting token into a frame • Token Release After transmit N/A After stripping (4) or after transmit (16) • Frames on a LAN Multiple Single 1 (4) or multiple(16) • Frames transmitted Multiple Single Single • per access • Maximum frame size 4500 bytes 1518 bytes 4,500 bytes (4) or 17,800 (16)

49. WAN Topologies • Dedicated Circuits • 56Kb • T-1 • DS-3 • Frame-Relay • 56Kb to T-1 speeds • Integrated Services Digital Network (ISDN)

50. Overview Introduction Topologies Network Transports Internetworking TCP/IP and the Internet Security Emerging Technologies