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COMMON LAYER 1 DEVICES AND FUNCTIONALITIES. Introduction. Devices will be covered starting at layer 1. 7. Routers, PAD’s, X.25 switches Bridges, LAN switches, ATM switches and terminal servers
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COMMON LAYER 1 DEVICES AND FUNCTIONALITIES
Introduction Devices will be covered starting at layer 1 7 • Routers, PAD’s, X.25 switches • Bridges, LAN switches, ATM switches and terminal servers • Transceivers, repeaters, hubs, FDDI concentrators, MSAU’s, modems, terminal adapters, DSU’s, CSU’s, MUX and NIC’s 6 5 4 3 2 1
Transceivers 7 6 • A transceiver connects a network device to the network cable • A transceiver listens to the bus to determine if it is being used by another station • A transceiver determines if the bus is being used by another station • A transceiver alerts the connected device when there is a collision during transmission • A transceiver may have DIP switches for controlling the exchange of SQE or heartbeat signals with the directly connected device. 5 4 3 2 1
Transceivers Attachment Interface Unit (AUI): The portion of the Ethernet standard that specifies how a cable is to be connected to an Ethernet card. AUI specifies a coaxial cable connected to a tranceiver that plugs into a 15-pin socket on the network interface card (NIC).
Repeaters 7 6 • A repeater is used to connect two segments of the same network • A repeater receives a signal from one segment, cleans and boosts the signal and sends it to the other segment • A repeater is responsible for ensuring that a collision is propagated to all attached segments • A repeater may be used to extend the network beyond the limitations of the network’s architecture by increasing segment length • Cannot add an infinite number of repeaters as this would adversely affect collision propagation. 5 4 3 2 1
Hubs 7 • A hub often attaches at least four nodes and many hubs include connectors for linking to other hubs • A hub provides connectivity by passing incoming signals to connected nodes • Hubs may be cascaded together to allow small workgroups with low-intensity applications to be formed • Hubs typically have LEDs to indicate the status of each port • Hubs may do partitioning to allow isolation of a non-functioning node • Hubs allow connection to different physical media. 6 5 4 3 2 1
NIC’s 7 • A NIC is an internetworking device that is a component part of a much larger host • NICs are used to connect the systems to the network • NICs will be different for each type of host system and type of network topology (and for each bus type) • Remote access is achieved through remote access to the host system • When installing a NIC it is important to consider the network topology, cabling and electrical considerations to avoid network disruption. 6 5 4 3 2 1