Bringing Up a Router

When you first bring up a Cisco router, it will run a power-on self-test (POST). If it passes, it will then look for and load the Cisco IOS from flash memory–if an IOS file is present. (Just in case you don’t know, flash memory is an electronically erasable programmable read-only memory– an EEPROM.) After that, the IOS loads and looks for a valid configuration–the startup-config– that’s stored by default in nonvolatile RAM, or NVRAM. The following messages appear when you first boot or reload a router:

System Bootstrap, Version 12.2(13)T, RELEASE SOFTWARE (fc1)
Copyright (c) 2000 by cisco Systems, Inc.
C2600 platform with 32768 Kbytes of main memory

This is the first part of the router boot process output. It’s information about the bootstrap program that first runs the POST, and then tells the router how to load, which by default is to find the IOS in flash memory.

The next part shows us that the IOS is being decompressed into RAM:

program load complete, entry point: 0×80008000, size:
0×43b7fc
Self decompressing the image :
###############################
###########################
################### [OK]

This step doesn’t happen the same way for all routers. The output you’re being shown is from 2600. It’s telling us that the IOS is being loaded into RAM. (The 2500 series router runs the IOS from flash memory—it doesn’t load the IOS into RAM.)

After the IOS is decompressed into RAM, the IOS is then loaded and starts running the router, as shown below (notice that the IOS version is stated as version 12.2[13]):

Cisco Internetwork Operating System Software
IOS ™ C2600 Software (C2600-I-M), Version 12.2(13),
RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2001 by cisco Systems, Inc.
Compiled Tue 17-Dec-03 04:55 by kellythw
Image text-base: 0×80008088, data-base: 0×8080853C

Once the IOS is loaded, the information learned from the POST will be displayed next, as shown here:

cisco 2621 (MPC860) processor (revision 0×101) with
26624K/6144K bytes of memory.
Processor board ID JAD050697JB (146699779)
M860 processor: part number 0, mask 49
Bridging software.
X.25 software, Version 3.0.0.
2 FastEthernet/IEEE 802.3 interface(s)
1 Serial network interface(s)
32K bytes of non-volatile configuration memory.
8192K bytes of processor board System flash (Read/Write)

Once the IOS is loaded, and up and running, a valid configuration will be loaded from NVRAM.

If there isn’t a configuration in NVRAM, the router will go into setup mode–a step-by-step process to help you configure the router. You can also enter setup mode at any time from the command line by typing the command setup from something called privileged mode, which I’ll get to in a minute. Setup mode only covers some global commands, but it can be really helpful
if you don’t know how to configure certain protocols, such as bridging or DECnet.

Hope this make you helpfully, click here to learn more how to logging into the cisco router.