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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 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/startup config 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 Internal components of a 2600 router Router external connections (2600) WAN interfaces LAN interfaces Management ports 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 Terminal console connection HyperTerminal settings 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?
