Routers

1. 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

2. Cisco Routers

3. 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.

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

5. 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

6. 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

7. 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

8. Routing

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

10. 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

11. 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

12. 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

13. Router Modes • User 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.

14. Router Modes • Set-up 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.

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

16. 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.

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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

24. 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.

25. 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.

26. 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.

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

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

29. 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.

30. 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

31. 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

32. Password configuration • Console password • Virtual terminal password • Privileged exec password

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

34. 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

35. 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

36. 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]

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

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

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

40. 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

41. 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 lab-a(config-if)#bandwidth 56

42. 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

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

44. 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