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Introduction to networking. Devices. Objectives. Be able to describe the common networking devices and their functionality, including: Repeaters Hubs Switches Bridges Routers. Icons. Repeater. This receives a signal from the network and then repeats it
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Introduction to networking Devices
Objectives • Be able to describe the common networking devices and their functionality, including: • Repeaters • Hubs • Switches • Bridges • Routers
Repeater • This receives a signal from the network and then repeats it • After a distance an electrical signal will lose power (attenuation) • This node increases the power of the signal again
Hub • Multi-port repeater • Shares bandwidth • Prone to collisions • Uses the Ethernet CSMACD technique to govern communication • Cheap • Generally non-configurable
Switch • Based on the Ethernet MAC address this node will forward the data to the correct host/machine • Creates micro-segments • Avoids the CSMACD issues of collision • Bandwidth is not divided between connected hosts • Provides Virtual LAN’s • Can be very basic and very advanced • Advanced models highly configurable
Bridge • Connects two segments of a network together • Only allows data to pass if the destination host/machine is located on the other segment • Preserves bandwidth
Routers • Similar to a bridge • Based on the IP Address this node will forward the data to the correct host/machine • Calculates the ‘best path’ • Also performs a switching function • Uses routing tables • Convergence • Uses routing protocols • Uses ACL’s (Access Control Lists) for security • ‘Knows’ the network • Can be very advanced, highly configurable
Routers • Internal components • D/RAM: storing routing tables, ARP cache, temporary and running memory for the config file • Loses data when powered down • NVRAM: stores backup/startupconfig file • Flash: EPROM, hold OS image, allows OS to be updated, can contain multiple OS’s • ROM: POST, bootstrap and basic OS • Interface: where packets enter and exit router
Routers • Routers can operate at all 7 levels of OSI, but mainly at levels 1-3 • Communication via level 1 and 2 refer to the routers switching function • Routes identify routes via layer 3 • Routers are quite simple physically, but very complicated logically due to its routing logic
Router internal components You will mostly experience the I/O interfaces and the IOS (the configuration file)
Router functions • One physical path must exist between source and destination • Having and using a path are not the same thing! • Source and destination must speak the same language (routed protocol), routers should also speak the same language (routing protocol), and agree on path • Functions therefore are: • Physical interconnectivity • Logical interconnectivity • Route calculation and maintenance • security
Router external connections (2600) WAN interfaces Management ports LAN interfaces WAN connections provide connections through a service Provider to a distant site or the Internet, often a CSU/DSU is required
Management ports • Text based CLI configuration and troubleshooting • Console and auxiliary are used for this (EIA-232 asynchronous serial ports) • Console is the preferred method of configuring as an administrator has access to router despite what state it is in and it allows the administrator to see and start-up messages
Summary • The main devices you will use are: • Switches • Routers • Hosts • Relevant cabling • Cisco Switches and Routers for the CCNA are very advanced and highly configurable
Questions... • ...are there any?