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?