Routers A router is a computer Computers have four basic components: a CPU, memory, interfaces, and a bus The router is a computer that selects the best paths, and manages the switching of packets between two different networks

Cisco Routers

Router - internal components RAM/DRAM Stores routing tables, ARP cache, fast-switching cache, packet buffering (shared RAM), and packet hold queues. also provides temporary and/or running memory for the router’s configuration file while the router is powered on. RAM content is lost when you power down or restart.

Router - internal components NVRAM non-volatile RAM stores a router’s backup/start-up configuration file; content remains when you power down or restart

Router - internal components Flash erasable, reprogrammable ROM holds the operating system image and microcode allows you to update software without removing and replacing chips on the processor content remains when you power down or restart multiple versions of IOS software can be stored in Flash memory

Router - internal components ROM contains power-on diagnostics, a bootstrap program, and operating system software software upgrades in ROM require replacing pluggable chips on the CPU

Router - internal components Interface network connection through which packets enter and exit a router it can be on the motherboard or on a separate interface module

Routing

Router Configuration A router is made up of configurable components. A router has modes examining, maintaining, and changing the components.

Router Configuration show commands are used for examination. You use cdp to show entries about neighbours. You access other routers by using telnet. You test network connectivity layer by layer. Testing commands include ping, trace, telnet, and debug

Router Configuration A router can be configured from many locations: Upon initial installation, it is configured from the console terminal. The console terminal is a computer connected to the router through the console port. It can be connected via modem by using the auxiliary port. After it is installed on the network, it can be configured from Virtual Terminals 0 through 4. Files can also be downloaded from a TFTP server on the network

Router Modes Whether accessed from the console or by a Telnet session through a TTY port, the router can be placed in several modes. Each mode provides different functions: User EXEC mode Privileged EXEC mode Set-up mode Global configuration mode Other configuration modes RXBOOT mode

Router Modes User EXEC mode Privileged EXEC mode A “look-only” mode in which the user can view some information about the router, but cannot change anything. Privileged EXEC mode Supports the debugging and testing commands, detailed examination of the router, manipulation of configuration files, and access to configuration modes.

Router Modes Set-up mode Global configuration mode Presents an interactive prompted dialog at the console that helps the new user create a first-time basic configuration. Global configuration mode Implements powerful one-line commands that perform simple configuration tasks.

Router Modes Other configuration modes RXBOOT mode Provide more detailed multiple-line configurations. RXBOOT mode A maintenance mode that can be used, among other things, to recover lost passwords.

Router Status Commands show version Displays the configuration of the system hardware, the software version, the names and sources of configuration files, and the boot image. show processes Displays information about the active processes.

Router Status Commands show protocols Displays the configured protocols. This command shows the status of all configured Layer 3 protocols. show mem Shows statistics about the router’s memory, including memory free pool statistics.

Router Status Commands show stacks Monitors the stack use of processes and interrupt routines and displays the reason for the last system reboot. show buffers Provides statistics for the buffer pools on the router. show flash Shows information about the Flash memory device.

Router Status Commands show running-config Displays the active configuration file. show startup-config Displays the backup configuration file. show interfaces Displays statistics for all interfaces configured on the router.

Cisco Discovery Protocol (CDP) CDP provides a single proprietary command that enables network administrators to access a summary of what the configurations look like on other directly connected routers. CDP runs over a data link layer connecting lower physical media and upper-network-layer protocols.

CDP Because CDP operates at this level, CDP devices that support different network-layer protocols can learn about each other. CDP starts up automatically at boot up. CDP can then automatically discover neighbouring Cisco devices running CDP.

CDP Discovered devices extend beyond those having TCP/IP. CDP discovers directly connected Cisco devices regardless of which Layer 3 and 4 protocol suite they run.

CDP CDP provides information about each CDP neighbour device. Values include the following: Device identifiers—For example, the router’s configured host name and domain name (if any) Address list—At least one address for SNMP, up to one address for each protocol supported Port identifier—Such as Ethernet 0, Ethernet 1, and Serial 0 Capabilities list—If, for example, the device acts as a source route bridge as well as a router Version—Information such as that provided by the local command show version Platform—The device’s hardware platform; for example, Cisco 7000

Cisco Router Configuration We have seen show and cdp commands show startup-config - display the backup configuration file show running-config—display active configuration file.

Cisco Router Configuration erase startup-config - deletes the backup configuration file in NVRAM. reload - reloads the router, causing it to run through the entire configuration process. Setup - to enter setup mode from the privileged EXEC prompt.

Cisco Router Configuration configure terminal—Configures manually from the console terminal. copy tftp running-config—Loads configuration information from a network TFTP server. copy running-config startup-config— Stores the current configuration from RAM into NVRAM.

Cisco Router Configuration copy running-config tftp — Stores the current configuration from RAM on a network TFTP server.

Cisco Router Configuration Router> enable password: Router# configure terminal Router(config)# [configure mode command] e.g. interface, subinterface, controller, line, router etc.

Cisco Router Configuration Specific configuration modes: interface mode - for configuring interfaces subinterface mode - for configuring multiple virtual interfaces on a single physical interface line mode - for configuring the operation of a terminal line router mode - for configuring an IP routing protocol etc.

Cisco Router Configuration Configuring router identification Router# config term Router(config)# hostname LABA LABA# ctrl-z : back to privileged exec mode exit : back out one level

Cisco Router Configuration Message of the day banner LABA(config)#banner motd # message # Interface description LABA(config)#interface ethernet 0 LABA(config-if)#description my LAN, BG

Password configuration Console password Virtual terminal password Privileged exec password

Console password LABA(config)#line console 0 LABA(config-line)#login LABA(config-line)#password cisco

Virtual Terminal password LABA(config)#line vty 0 4 LABA(config-line)#login LABA(config-line)#password cisco Enable Password LABA(config)#enable password class or prefer LABA(config)#enable secret class

Configuring interfaces LABA(config)#int s 0 LABA(config-if)#clock rate 56000 clk rate is set for DCEs LABA(config-if)#bandwidth 56 no clock rate removes clock rate shut down/no shut down

Configuring routing protocols LABA(config)#router rip LABA(config-router)#network 1.0.0.0 LABA(config-router)# network 2.0.0.0 LABA(config-router)#ctrl-z LABA(config)#ctrl-z LABA#show ip protocol LABA#show ip route [routing table]

Configuring routing protocols LABA>show ip interfaces LABA#debug ip rip

Exercise - Configuring LABA Hostname: Router>ena password: Router#config term Router(config)#hostname lab-a

Exercise - Configuring LABA Enable secret password - class lab-a(config)#enable secret class

Exercise - Configuring LABA All appropriate interfaces with IP addresses and subnet masks lab-a(config)#int s 0 lab-a(config-if)#ip address 201.100.11.1 255.255.255.0 lab-a(config-if)#clockrate 56000 lab-a(config-if)#bandwidth 56

Exercise - Configuring LABA lab-a(config)#int e 0 lab-a(config-if)#ip address 192.5.5.1 255.255.255.0 lab-a(config-if)#bandwidth 56 lab-a(config)#int e 1 lab-a(config-if)#ip address 205.7.5.1 255.255.255.0

Exercise - Configuring LABA Configure rip lab-a(config)#router rip lab-a(config)#network 205.7.5.0 lab-a(config)# network 192.5.5.0 lab-a(config)# network 201.100.11.0

Exercise - Configuring LABA Console login password - cisco lab-a(config)#line console 0 lab-a(config-line)#login lab-a(config-line)#password cisco

Exercise - Configuring LABA Vty login password - cisco lab-a(config)#line vty 0 4 lab-a(config-line)#login lab-a(config-line)#password cisco