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WXES2106 Network Technology Semester 1 2004/2005 Chapter 2 Networking Media CCNA1: Module 3, 4 and 5 Contents Introduction Copper Media Optical Media Wireless Media Cable Testing Cabling the LAN Cabling the WAN Introduction Proper selection of cabling is key to efficient network operation. Copper cable is used in almost every LAN Optical fiber is the most frequently used medium for the longer, high bandwidth, point-to-point transmissions required on LAN backbones and on WANs. Different specifications for cable Speed of bit transmission (bps) Transmission type (Base or Broad) Maximum distance Example: 10BASE-T, 10BASE5, 10BASE2 Introduction Copper Media Coaxial Cable Longer distance Thicknet coaxial cable more expensive to install Copper Media Screened UTP (ScTP) Shielded twisted-pair cable (STP) Copper Media UnShielded twisted-pair cable (STP) Easy to install and less expensive Type of connection: Straight through, Crossover, Rollover Copper Media Straight through Crossover Rollover Optical Media Optical Media Every fiber-optic cable used for networking consists of two glass fibers encased in separate sheaths. One fiber carries transmitted data from device A to device B. The second fiber carries data from device B to device A. This provides a full-duplex communication link. Optical Media Optical Media Connectors are attached to the fiber ends so that the fibers can be connected to the ports on the transmitter and receiver. Subscriber Connector (SC connector) - Multimode fiber Straight Tip (ST) connector - Single-mode fiber Optical Media Optical Receiver Use PIN photodiodes to detect laser/LED light PIN photodiodes absorb light of 850, 1310, or 1550 nm When detects light, produces electrical signal for network Installation of Fiber Pull fiber through interducting (stiffer piping) to reduce bends Cleave (cut) & polish ends Attach connector Optical Media Wireless Media Standard 802.11b (Wi-Fi) 802.11a 802.11g Max. Typical Bandwidth throughput 11 Mbps 54 Mbps 54 Mbps 2-4 Mbps Freq. Band 2.4 GHz 20-26 Mbps 5 GHz 15-26 Mbps 2.4 GHz Wireless Media A wireless network may consist of as few as two devices Access Point Central hub for WLAN It is hard wired to the cabled LAN to provide Internet access and connectivity to the wired network. Equipped with antennae and provide wireless connectivity over a specified area referred to as a cell. The range will be from 91.44 to 152.4 meters Wireless NIC Wireless Media Wireless Connectivity When a client is activated within the WLAN, it will start "listening" for a compatible device with which to "associate". A probe request is sent from the wireless node seeking to join the network. The probe request will contain the Service Set Identifier (SSID) of the network it wishes to join. When an AP with the same SSID is found, the AP will issue a probe response. The authentication and association steps are completed. Wireless Media Authentication and Association types Unauthenticated and unassociated The node is disconnected from the network and not associated to an access point. Authenticated and unassociated The node has been authenticated on the network but has not yet associated with the access point. Authenticated and associated The node is connected to the network and able to transmit and receive data through the access point. Wireless Media Authentication Process Open System The SSID must match. Shared Key Requires the use of Wireless Equivalency Protocol (WEP) encryption. Nodes attempting to access the network through the AP must have a matching key. Wireless Media Frame Type Adaptive Rate Selection Wireless Media Wireless Security EAP-MD5 Extensible Authentication Protocol LEAP (Cisco) Lightweight Extensible Authentication Protocol Provides security during credential exchange, encrypts using dynamic WEP keys, and supports mutual authentication. User authentication Encryption Data authentication Cable Testing Inferior quality of network cabling results in network failures and unreliable performance. All media require testing to determine the quality. Attenuation (signal deterioration) and noise (signal interference) cause problems in networks because the data is not recognizable when it is received. Proper attachment of cable connectors and proper cable installation are important. Cable Testing Cable Testing Standard Wire map Insertion loss Near-end crosstalk (NEXT) Power sum near-end crosstalk (PSNEXT) Equal-level far-end crosstalk (ELFEXT) Power sum equal-level far-end crosstalk (PSELFEXT) Return loss Propagation delay Cable length Delay skew Cable Testing Cabling the LAN Media Types Symbol Cabling the LAN LAN Physical Layer Implementation Cabling the LAN Ethernet is the most widely used LAN technology. An Ethernet speed of 10 Mbps can be used at the user level to provide good performance. Fast Ethernet can be used to connect enterprise servers. Cabling the LAN Ethernet Media Cabling the LAN Ethernet Media Cabling the LAN Straight-through Switch to router Switch to PC or server Hub to PC or server Crossover Switch to switch Switch to hub Hub to hub Router to router PC to PC Router to PC Rollover A terminal and a console port Cabling the LAN Wireless networks use radio Frequency (RF), laser, infrared (IR), or satellite/microwaves to carry signals from one computer to another without a permanent cable connection. A wireless network can be created with much less cabling than other networks. Cabling the LAN In LAN design, no more than four repeaters can be used between hosts on a LAN. This rule is used to limit latency added to frame travel by each. Using a hub changes the network topology from a linear bus, where each device plugs directly into the wire, to a star. Bridge break up a large LAN into smaller, more easily managed segments. Switch alleviates congestion in Ethernet LANs by reducing the traffic and increasing the bandwidth. It operates at much higher speeds than bridges and can support new functionality, such as virtual LANs. Cabling the LAN Micro Segmentation of Network Cabling the LAN Peer-To-Peer Networked computers act as equal partners, or peers. As peers, each computer can take on the client function or the server function. Client/Server Network services are located on a dedicated computer called a server. The server responds to the requests of clients. The server is a central computer that is continuously available to respond to requests from clients Cabling the LAN Cabling the LAN Cabling the WAN WAN Physical Layer Cabling the WAN WAN Serial Connection Cabling the WAN Routers are responsible for routing data packets from source to destination within the LAN, and for providing connectivity to the WAN.