Upon reading the document, the key steps in a router's start-up process can be summarized as follows: 1. When power is applied, the router performs a power-on self-test and loads the bootstrap code from ROM to initialize hardware and find the IOS image. 2. The IOS image is then loaded from flash memory or another source such as TFTP into RAM where it is decompressed and executed. 3. The startup configuration is loaded, typically from NVRAM. If no configuration is present, the router enters setup mode to configure initial settings.

4. Using CDP Switch A Switch B Router A Router B RouterA#sh cdp ? 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 Entry information for specific neighbor entry Interface CDP interface status and configuration Traffic CDP statistics neighbors CDP neighbor entries <cr> RouterA(config)#no cdp run RouterA(config)#interface serial0 RouterA(config)#no cdp enable

5. Using the show cdp neighbor Command RouterA#sh cdp neighbors 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 Capability codes: R – Router, T- Trans Bridge, B – Source Route Bridge S – Switch, H – Host, I – IGMP, r - Repeater Device ID Local Interface Holdtme Capability Platform Port ID RouterB Ser 0 148 R 2522 Ser 1 SwitchA0050bd855780 Eth 0 167 T S 1900 2 Switch also provides its Mac address Switch A Switch B Router A Router B

6. Using the show cdp entry Command Switch A Switch B Router A Router B RouterA#sh cdp entry 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 Device ID: RouterB Entry address(es): IP address: 10.1.1.2 Platform: cisco 2522, Capabilities: Router Interface: Serial0, Port ID (outgoing port): Serial Holdtime : 168 sec Version : Cisco Internetwork Operating System Software IOS (tm) 2500 Software (C2500-JS-L), Version 12.0(3), RELEASE SOFTWARE (fci) Copyright (c) 1986-1999 by cisco Systems, Inc. Compiled Mon 080-Feb-99 18:18 by phanguye

7. Additional CDP Commands Switch A Switch B Router A Router B RouterA#sh cdp traffic 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 CDP counters : Packets output: 56, Input: 38 Hdr syntax: 0, Chksum error: 0, Encaps failed: 3 No memory: 0, Invalid packet: 0, Fragmented: 0 RouterA#sh cdp interface BRIO is administratively down, line protocol is down Encapsulation HDLC Sending CDP packets every 60 seconds Holdtime is 180 seconds

8. Using Telnet to Connect to Remote Devices RouterA# telnet 10.2.2.2 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 Trying 10.2.2.2 ... Open Catalyst 1900 Management Console All rights reserved. Copyright © Cisco Systems, Inc. 1993-1998 Enterprise Edition Software Ethernet Address: 00-90-86-73-33-40 PCA Number: 73-2239-06 PCA Serial Number: FAA02359H8K Model Number: WS-C1924-EN System Serial Number: FAA0237X0FQ SwitchB> Remote device Switch A Switch B Router A Router B

9. Viewing Telnet Connections Switch A Switch B Router A Router B RouterA#sh session 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 Conn Host IP Address Byte Idle Conn Name 1 10.1.1.2 10.1.1.2 0 1 10.1.1.2 2 10.3.3.2 10.3.3.2 0 0 10.3.3.2 RouterA#sh user Line User Host(s) Idle Location 0 con 0 10.1.1.2 3 10.3.3.2 2 11 vty 0 idle 1 10.1.1.2

10. Suspending a Telnet Session Switch A Switch B Router A Router B RouterB#<Ctr1-Shift-6>x 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 RouterA#sh session Conn Host IP Address Byte Idle Conn Name 1 10.1.1.2 10.1.1.2 0 1 10.1.1.2 RouterA#resume 1 RouterB#

11. Closing a Telnet Session Switch A Switch B Router A Router B 10.3.3.2 10.3.3.1 10.1.1.1 10.1.1.2 10.2.2.1 10.2.2.2 S1 S0 RouterA#disconnect Closing the current Closing connection to 10.3.3.2 [confirm] session opened by you RouterA#clear line 11 Closing a session opened by a remote device [confirm] [OK]

12. Using the Ping and trace Commands Router##ping 10.1.1.10 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.1.10, timeout is 2 seconds: !!!!! Router#trace 10.1.1.10 Success rate is 100 percent (5/5), round-trip min/avg/max =4/4/4 ms Type escape sequence to abort. Tracing the route to 10.1.1.10 1 10.1.1.10 4 msec 4 msec 4 msec Router# Test connectivity and path to remote device

14. Router Internal Components RAM Flash ROM NVRAM Config register Interfaces

15. ROM Functions ROM Bootstrap POST Mini IOS ROM monitor Contains microcode for basic function Show version Console

18. Loading the IOS from Flash IOS RAM IOS Flash Console Flash file is decompressed into RAM Show flash

21. RAM NVRAM Flash TFTPserver Cisco IOS Systems and Devices tftp: nvram: system: flash:

22. Managing IOS Images Router c2500-js-1_120-3.bin Network server Network server FLASH

24. Network server FLASH Creating a Software Image Backup Wg_ro_a#copy flash tftp Source filename []? c2500-js-1_120-3.bin Address or name of remote host []? 10.1.1.1 Destination file name [C2500-js-1_120-3.bin]? !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! <output omitted> 10084696 bytes copied in 709.228 secs (14223 bytes/sec) Wg_ro_a# Back up current files prior to updating flash

26. Determining the current configuration Register Value Wg_ws_a # show version Cisco Internetwork Operating System Software IOS™ 2500 software { c2500 _js_L} , version 12.0(3) , RELEASE SOFTWARE { fci} Copyright {c} 1986_1999 by cisco Systems ,Inc. compiled Mon 18_Feb_99 18:18 by Phanguye Image text_base: 0x03050c84 . Data _base: 0x00001000 ROM : system Bootstrap , version 11.0 SOFTWARE Bootflash : 3000 bootstrap software (IGS_BOOT_R), version 11.0 (10c), RELEASE SOFTWARE {fci} wg_ro_a uptime is 20 minutes system restarted by reload system image file is “ flash : c2500_js_l_120_3.bin” -----more------ configuration register is 0x 2102

27. Show Flash Command Wg_ws_a # show flash system flash directory: File Length Name/Status 1 10084696 c2500_js_ l_120_3. Bin [ 10084760 bytes used, 6692456 available , 16777216 total } 1638k bytes of processor board system flash { read only}

28. Show running and show startup commands Wg_ro_c#show running-config building configuration: ! Version 12.0 ! - - More - - Wg_ro_c#show startup-config using 1359 out of 32762 bytes ! Version 12.0 - - More - - In RAM In NVRAM

29. Determining the current configuration Register Value Wg_ws_a # show version Cisco Internetwork Operating System Software IOS™ 2500 software { c2500 _js_L} , version 12.0(3) , RELEASE SOFTWARE { fci} Copyright {c} 1986_1999 by cisco Systems ,Inc. compiled Mon 18_Feb_99 18:18 by Phanguye Image text_base: 0x03050c84 . Data _base: 0x00001000 ROM : system Bootstrap , version 11.0 SOFTWARE Bootflash : 3000 bootstrap software (IGS_BOOT_R), version 11.0 (10c), RELEASE SOFTWARE {fci} wg_ro_a uptime is 20 minutes system restarted by reload system image file is “ flash : c2500_js_l_120_3.bin” -----more------ configuration register is 0x 2102

30. Determining the current configuration Register Value Wg_ws_a # show version Cisco Internetwork Operating System Software IOS™ 2500 software { c2500 _js_L} , version 12.0(3) , RELEASE SOFTWARE { fci} Copyright {c} 1986_1999 by cisco Systems ,Inc. compiled Mon 18_Feb_99 18:18 by Phanguye Image text_base: 0x03050c84 . Data _base: 0x00001000 ROM : system Bootstrap , version 11.0 SOFTWARE Bootflash : 3000 bootstrap software (IGS_BOOT_R), version 11.0 (10c), RELEASE SOFTWARE {fci} wg_ro_a uptime is 20 minutes system restarted by reload system image file is “ flash : c2500_js_l_120_3.bin” -----more------ configuration register is 0x 2102

31. Determining the current configuration Register Value Wg_ws_a # show version Cisco Internetwork Operating System Software IOS™ 2500 software { c2500 _js_L} , version 12.0(3) , RELEASE SOFTWARE { fci} Copyright {c} 1986_1999 by cisco Systems ,Inc. compiled Mon 18_Feb_99 18:18 by Phanguye Image text_base: 0x03050c84 . Data _base: 0x00001000 ROM : system Bootstrap , version 11.0 SOFTWARE Bootflash : 3000 bootstrap software (IGS_BOOT_R), version 11.0 (10c), RELEASE SOFTWARE {fci} wg_ro_a uptime is 20 minutes system restarted by reload system image file is “ flash : c2500_js_l_120_3.bin” -----more------ configuration register is 0x 2102

32. Router Start-up Flow Chart