Local Area Networks. What is a Network Network Models. OSI Layers LAN Topologies Other local communications protocols used on slot floors OSI TCP/IP

Transcription

1 Local Area Networks What is a Network Network Models OSI TCP/IP OSI Layers LAN Topologies Other local communications protocols used on slot floors

2 Network Definition A network is a system of interconnected objects or people. There are many different types of networks. A computer network is defined as having two or more devices such as workstations, printers, and servers linked together for the purpose of sharing information. Copyright 2003 Cisco Press

3 Network Definition Casino Systems Slot machines are connected together within a casino via local area networks (LANs) This LAN connection is known through the industry as an Casino/Slot Management System There are many casino/slot management systems supplied by machine manufactures and independent suppliers Too many to be studied individually We will cover the concepts First of Ethernet based connections Then of the older slower speed connections such as RS-232 & RS-485

4 Network Definition Casino Systems Casino/Slot Management System Originally a cash accounting and surveillance system for games, whereby operation of a number of player operated gaming devices may be monitored for purposes of detecting abnormal operation and/or cheating and for providing automatic accounting information for record keeping and pilferage detection purposes Evolved into a system for monitoring and configuring gaming devices interconnected over a high-speed network. The system can support a file server, one or more floor controllers, one or more pit terminals, and other terminals all interconnected over the network

6 Benefits of Networking Sharing Output Devices Printers, other output devices, and fax machines can be shared. Sharing Input Devices High-end devices are typically used occasionally and are often expensive so it makes sense to configure them for multiple users on the network. Sharing Storage Devices Files can be saved on these storage devices and accessed from anywhere on the network.

7 More Benefits of Networking Sharing internetworking connections With the proper software, an entire LAN can connect other networks through a single connection Security It is much easier to secure data and resources when policies and enforcement are centralized and managed Sharing Data and Applications Sharing data files result in the efficient use of disk space and easier collaboration on multi-user projects.

8 Network Model A method of describing and analyzing data communications networks Breaking the entire set of communications functions into a series of layers Each layer can be defined separately Eases development of software and hardware to provide the layer functions Open System Interconnection (OSI) Model, developed in 1984 TCP/IP is older and is more prominent

9 Network Model OSI Reference Model Open Systems Interconnection Model Developed by International Standards Organization in 1984 Not a Protocol but a model that protocols are developed to implement Seven Layers The OSI reference model is used universally as a method for teaching and understanding network functionality. Following the OSI model when designing, building, upgrading, or troubleshooting will achieve greater compatibility and interoperability between various types of network technologies.

10 Reasons for using the OSI model Divides the aspects of network operation into less complex elements. Enables engineers to specialize design and development efforts on specific functions. Prevents changes in one area from affecting other areas, so that each area can evolve more quickly. Allows network designers to choose the right networking devices and functions for that layer. Helps with testing and troubleshooting. Copyright 2003 Cisco Press

12 Network Model Physical Layer Physical This layer provides the electrical, mechanical, procedural, and functional means for activating and maintaining whatever physical link exists between hosts. If the link between hosts or networks is severed or experiencing problems, data may not transmit. Networking media such as twisted-pair, coaxial, and fiber-optic cable are layer 1 equipment. Data Link Two Sub-layers Media Access Control (MAC) and Logical Link Control (LLC)

13 Network Model Data Link Layer This layer deals with speed of transmission, flow control, error identification, and topology Layer recognizes identifiers that are unique to each computer Media access control (MAC) addresses Built into most hardware MAC Definitions Physical or MAC address» 6-bytes express Three 4-digit Hex Numbers» 6-bytes expressed ass Six 2-digit Hex Numbers Switches operate at this layer

14 Network Model Network Layer The layer adds logical or network addresses, such as Internet Protocol (IP) addresses to information that passes through it With the addition of this information, the frames are now called packets. This layer is responsible for determining the best way to move data from one network to another Routers perform this operation and are thus referred to as Layer 3 devices.

15 Network Model Transport Layer This layer takes the data file and divides it up into segments to facilitate transmission This layer is also responsible for reliable delivery of data between the two hosts Services Repackaging Error Control End-to-end flow control TCP part of TCP/IP operates at this layer

16 Network Model Secessions Layer The session layer establishes, maintains, and manages conversations, called sessions, between two or more applications on different computers Can restart sessions that were interrupted The session layer is involved in keeping the lines open for the duration of the session and disconnecting them at the conclusion

17 Network Model Presentation Layer This layer provides formatting services For application layer by ensuring the data that arrives from another computer can be used by an application For instance, it translates EBCDIC characters from mainframe computers into ASCII characters for PCs so that an application can read the data Graphic example, it is capable of translating image formats from TIFF to JPEG or GIFF This layer is also responsible for encryption and compression

18 Network Model Applications Layer The main function of the application layer is to provide network services to the end user and programs These network services include file access, applications, and printing

19

20

21 TCP/IP and OSI Model Comparison Application TCP (Transport) Transport Internet Network Covered by many Standards Media Dependent

22 Network topologies Computer networks have physical and logical topologies. Physical topology Layout of the networking cables, devices, and workstations aka, Were the wires are placed Logical topology Dictate the path data takes between devices and computers Logical connections between devices Every network has logical & physical topologies.

23 Physical Topologies Types of physical topologies Image Copyrighted 2003 Cisco Press

24 The Bus Topology A physical bus topology uses a single length of cable Cable runs from one end of the network to the other. Users are connected to the central cable by segments of cable Only in Very old installs Pre 1995 Image Copyrighted 2003 Cisco Press

25 Ring and Dual Ring Topologies In a physical ring topology, all devices are connected in a circle The dual-ring topology provides additional reliability since it has two paths for traffic Ring Dual Ring Image Copyrighted 2003 Cisco Press NOTE: Only in older Installs Gig Ethernet over copper is five times faster

26 The Star & Extended Star Topology Star connects all cables to a central point. Extended star topology is created by linking together several star topologies to a central point Used on most modern installs Star Extended Star Ring Image Copyrighted 2003 Cisco Press

27 The Hierarchical Topology The hierarchical topology imposes order By grouping hosts based on their physical location on the network NOTE: Usually only in older networked systems Hierarchical Image Copyrighted 2003 Cisco Press

28 Mesh Topology A mesh topology connects each host to every other host Provides redundancy Very expensive The number of Links grows exponentially with each added node # of Links = (Nodes!) / ([Nodes- 2]! 2!) Mesh Image Copyrighted 2003 Cisco Press

29 Non-Ethernet LANs Many of the Casino/Slot Management Systems use low speed serial communications for the last link to EGMs Such as current loops, RS-422, and RS ma Current Loops succeeded 60mA & 30mA loops Could send 19.2kbps over distances of 2000 Much better than RS kbps over 50 RS 422 and RS 485 Both could send 100kbps over 4000 Both are also capable of 10Mbps at 50 or less Both are multi-drop protocols RS-422, 5 transmitters and 10 Receivers RS-485, 32 transmitters and 32 Receivers

30 Non-Ethernet LANs RS232 RS422 RS485 Cabling single ended single ended multi-drop multi-drop Number of Devices 1 transmit 1 receive 5 transmitters 10 receivers 32 transmitters 32 receivers Communication Mode full duplex full duplex half duplex half duplex Max. Distance 50 feet at 19.2 Kbps 4000 feet at 100 Kbps 4000 feet at 100 Kbps Max. Data Rate 19.2 Kbps for 50 feet 10 Mbps for 50 feet 10 Mbps for 50 feet Signaling unbalanced balanced balanced Mark (data 1) -5 V min. -15 V max. 2 V min. (B>A) 6 V max. (B>A) 1.5 V min. (B>A) 5 V max. (B>A) Space (data 0) 5 V min. 15 V max. 2 V min. (A>B) 6 V max. (A>B) 1.5 V min. (A>B) 5 V max. (A>B) Input Level Min. +/- 3 V 0.2 V difference 0.2 V difference Output Current 500 ma (Note that the driver ICs normally used in PCs are limited to 10 ma) 150 ma 250 ma

31 Non-Ethernet LANs RS485 Multidrop Wiring Sometimes termed as RS485 Multidrop LAN Since it can connect several devices in a LAN network environment. These devices are all connected to a single pair wire. Transmit and receive share the same two wires Officially the RS485 specification allows only 32 nodes (devices) on the LAN However, I.C. manufacturers have developed RS485 drivers capable of allowing 128 to 255 nodes on an RS485 LAN