1. CISCO NETWORKING ACADEMY Chabot College ELEC 99.08 Router Components & “Show” Commands

2. CISCO NETWORKING ACADEMY Internal Components RAMNVRAMFlashROM Interfaces Console Auxiliary

3. CISCO NETWORKING ACADEMY RAM Temporary storage for router configuration files RAM content is lost on power down or restart Stores... –Routing tables –ARP cache –Fast switching cache –Packet buffering

4. CISCO NETWORKING ACADEMY NVRAM Non-volatile RAM Stores backup/startup configuration files Content is not lost when router is powered down or restarted.

5. CISCO NETWORKING ACADEMY Flash EEPROM (Electronically Erasable Programmable Read-Only Memory) Holds the Cisco IOS (Internetworking Operating System) Allows updating of software without replacing the Flash chip Multiple versions of IOS can be stored Retained on power down

6. CISCO NETWORKING ACADEMY ROM Contains POST (Power On Self Test) A bootstrap program (loads the Cisco IOS) And mini-operating system software: –Backup, trimmed down version of the IOS –Upgrades require installing new chip set

7. CISCO NETWORKING ACADEMY Interfaces Network connections through which packets enter and exit the router Attached to the motherboard or as separate modules on “modular” routers.

8. CISCO NETWORKING ACADEMY RAMNVRAMFlashROM Interfaces Console Auxiliary As the router is booted, the following is loaded into RAM’s Working Storage. RAM Specifics RAM Command Executive Internetwork Operating System (IOS) Programs Active Config File TablesBuffers

9. CISCO NETWORKING ACADEMY Programs include the bootstrap program that tests the equipment (POST) and locates the IOS. RAM Specifics RAM Programs

10. CISCO NETWORKING ACADEMY RAM Specifics RAM Internetwork Operating System (IOS) Programs Once the IOS is located by the bootstrap program, it is loaded in to RAM.

11. CISCO NETWORKING ACADEMY RAM Specifics RAM Command Executive Internetwork Operating System (IOS) Programs Part of the IOS is the Command EXEC. This is the program that translates the commands you type into a language that the IOS can understand.

12. CISCO NETWORKING ACADEMY RAM Specifics RAM Command Executive Internetwork Operating System (IOS) Programs Active Config File Once the IOS is initialized, it looks for an active configurations file (usually in NVRAM) and loads it. This file tells the router specifically what to do.

13. CISCO NETWORKING ACADEMY RAM Specifics RAM Command Executive Internetwork Operating System (IOS) Programs Active Config File Tables The tables are loaded from the configuration file including... ARP Tables Routing Tables

14. CISCO NETWORKING ACADEMY RAM Specifics RAM Command Executive Internetwork Operating System (IOS) Programs Active Config File TablesBuffers Finally, all leftover memory in RAM is used as the buffer for processing incoming and outgoing packets.

15. CISCO NETWORKING ACADEMY Router Status Commands “Show” commands yield status information about various router components, as shown on the next slides...

16. CISCO NETWORKING ACADEMY Example Show Commands show version –displays: configuration of the system hardware IOS version names and sources of configuration files the current setting of the configuration register (used in password recovery)

17. CISCO NETWORKING ACADEMY Example Show Commands show version Try it now with Router e-SIM: –Start Router e-SIM –Give all your routers a configuration: click SHOW DONE in the row of SET buttons at the bottom, click A, B, C, D, E click HIDE DONE –Login - Password - cisco –Enable privileged mode: Secret Password: class

18. CISCO NETWORKING ACADEMY Example Show Commands show running-config –displays the active configuration file loaded in RAM Try it now with Router e-SIM

19. CISCO NETWORKING ACADEMY Example Show Commands show startup-config –displays the backup configuration file stored in NVRAM Try it now with Router e-SIM: Your router will not have a startup configuration until you save the running configuration to the startup file: Lab_A# copy run start Now try show start again

20. CISCO NETWORKING ACADEMY Example Show Commands show interfaces –displays statistics for all interfaces configured on the router Try it now with Router e-SIM.

21. CISCO NETWORKING ACADEMY Example Show Commands show protocols –displays the status of all configured Layer 3 protocols –displays the status of all interfaces Try it now with Router e-SIM.

22. CISCO NETWORKING ACADEMY Example Show Commands show ip route –displays the routes to all networks known to the router Try it now with Router e-SIM.

23. CISCO NETWORKING ACADEMY Example Show Commands show controller –displays information about each interface controller. Key: shows whether serial interface is DTE or DCE (setting determined by the connected cable). Important mainly in Cisco lab, where some routers are configured DCE. Router e-SIM doesn’t understand this command, so you’ll need to try it on a real router...

24. CISCO NETWORKING ACADEMY FlashNVRAMRAM Internetwork Operating System Programs Active Configuration File Tables and Buffers Backup Configuration File Operating Systems Interfaces Router#show versionRouter#show flashRouter#show interfaces Router#show processes CPU Router#show protocols Router#show running-config Router#show ip route Router#show buffers Router#show startup-config