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Chabot College

Chabot College. ELEC 99.08 Router Components & “Show” Commands. RAM. NVRAM. Flash. ROM. Console. Interfaces. Auxiliary. Internal Components. RAM. Temporary storage for router configuration files RAM content is lost on power down or restart Stores... Routing tables ARP cache

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Chabot College

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

  2. RAM NVRAM Flash ROM Console Interfaces Auxiliary Internal Components

  3. 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. NVRAM • Non-volatile RAM • Stores backup/startup configuration files • Content is not lost when router is powered down or restarted.

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

  8. RAM NVRAM Flash ROM Console Interfaces Auxiliary RAM Specifics As the router is booted, the following is loaded into RAM’s Working Storage. Command Executive Internetwork Operating System (IOS) RAM Programs Active Config File Tables Buffers

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

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

  11. RAM RAM Specifics 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. Command Executive Internetwork Operating System (IOS) Programs

  12. RAM RAM Specifics 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. Command Executive Internetwork Operating System (IOS) Programs Active Config File

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

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

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

  16. 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. 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. Example Show Commands show running-config • displays the active configuration file loaded in RAM Try it now with Router e-SIM

  19. 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. Example Show Commands show interfaces • displays statistics for all interfaces configured on the router Try it now with Router e-SIM.

  21. 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. Example Show Commands show ip route • displays the routes to all networks known to the router Try it now with Router e-SIM.

  23. 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. Router#show interfaces Router#show version Router#show flash Router#show ip route Router#show buffers Router#show processes CPU Router#show protocols Router#show running-config Router#show startup-config RAM NVRAM Flash Internetwork Operating System Backup Configuration File Operating Systems Interfaces Programs Active Configuration File Tables and Buffers

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