ROM, RAM, NVRAM and Flash Memory on Cisco Routers _ Confterminal

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ROM, RAM, NVRAM and Flash Memory onCisco Routers

Saturday 12 March 2011 2 comments

introduction

Sometimes people get confused when it comes to telling how much memory the router has and which memory

does what. There are 4 memory terms you should be familiar with, and 2 of these should be checked before

upgrading the router's IOS. These are the following:

ROM: ROM stands for Read Only Memory. It stores the System Bootsrap.

NVRAM: This is where the configuration is saved when you type copy run start.

RAM: RAM stores the running config, CDP information, ARP cache, routing table, etc. Basically everything the

router needs for it's operation. Before you upgrade the IOS you should check if the router has sufficient memoryto run that particular IOS!

FLASH: This is where the IOS is stored. Before upgrading you should check if the flash is big enough to hold the

old and the new images or that you have to delete the old one before downloading the new one.

To check the memory type in show verison

AS#show versionCisco Internetwork Operating System SoftwareIOS (tm) 2500 Software (C2500-I-L), Version 12.1(3)T, RELEASE SOFTWARE (fc1)Copyright (c) 1986-2000 by cisco Systems, Inc.Compiled Wed 19-Jul-00 06:05 by ccaiImage text-base: 0x03042200, data-base: 0x00001000

ROM: System Bootstrap, Version 11.0(10c)XB1, PLATFORM SPECIFIC RELEASE SOFTWARE (fc1)BOOTFLASH: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c)XB1, PLATFORM SPECIFIC RELEASE SOFTWARE (fc1)

AS uptime is 30 minutesSystem returned to ROM by reloadSystem image file is "flash:c2500-i-l.121-3.t.bin"



cisco AS2511-RJ (68030) processor (revision K) with 6144K/2048K bytes of memory.Processor board ID 17142046, with hardware revision 00000000Bridging software.X.25 software, Version 3.0.0.1 Ethernet/IEEE 802.3 interface(s)1 Serial network interface(s)16 terminal line(s)32K bytes of non-volatile configuration memory.8192K bytes of processor board System flash (Read ONLY)

Configuration register is 0x2102

AS#

The highlighted values:

6144K/2048K: This is the amount of installed memory (RAM or DRAM). DRAM is divided logically so you

need to combine the two numbers to determine the total memory. 6144+2048=8192K.

32K: NVRAM to save the configuration file. It appears to be very small but because the config is just a text file it

can hold a huge amount of data. Even this tiny 32K can store about a 1000-1500 lines of code! It's handy to

know thought that if you need more space to store your startup configuration you can configure the router tostore it on the flash or boot from a TFTP server.

8192K: This is the size of the flash memory where the IOS is stored.

scenario

Let's say we want to upgrade this Access Server. It is currently running c2500-i-l.121-3.t and we want to

upgrade to c2500-is-l.122-8.T. First we have to check the IOS requirements on the Cisco Feature Navigatorsite to see if we have enough RAM and if the image would fit on the flash.



We can see that both, the RAM and the flash have to be 16MB/16MB in order to be able to use this IOS. Wehave only 8MB of RAM and 8MB of flash so the upgrade is going to have to happen after a quick shopping on

ebay! :)

Categories: Cisco Tags: Cisco General|IOS|Monitoring

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Comments

1. mm

12:58 07 Mar 2014The total RAM installed is 6144K + 2048K, is it not?

2. Szilard

09:39 29 Mar 2014Thank you for pointing it out, it has been corrected

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Recent Comments

Szilardsaid:

Thank you for pointing it out, it has been correctedmore

mmsaid:The total RAM installed is 6144K + 2048K, is it not?

more

Szilardsaid:

It looks like that the simulator you are using is not up to the task. Try downloading Packet Tracer, that is a good

sim to start...more



Percysaid:

the error that comes is: % Invalid input detected at '^' marker and '^' is pointing to authentication.... i "typed

debu...more

Szilardsaid:

When you say that "debug ppp authentication" doesn't work do you mean that there is no output or the router

doesn't accept it? T...

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Percysaid:

I tried this method, but i have a problem... the command "debug ppp authentication" and "service password-encryption" dont w...

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