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: 0x80008000, size:
0x43b7fc
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 (tm) 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: 0x80008088, data-base: 0x8080853C
Once the IOS is loaded, the information learned from the POST will be
displayed next, as shown here:
cisco 2621 (MPC860) processor (revision 0x101) 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) |