Chapter 1 Cisco 1721 Router Overview
Router Memory
Types of Memory
The Cisco 1721 router has the following types of memory:
•Dynamic random-access memory (DRAM)—This is the main storage memory for the router. DRAM is also called working storage. It contains the dynamic configuration information. The Cisco 1721 router stores a working copy of the Cisco IOS software, dynamic configuration information, and routing table information in DRAM.
•Nonvolatile random-access memory (NVRAM)—This type of memory contains a backup copy of your configuration. If the power is lost or the router is turned off, this backup copy enables the router to return to operation without reconfiguration.
•Flash memory—This special kind of erasable, programmable memory contains a copy of the Cisco IOS software. The Flash memory structure can store multiple copies of the Cisco IOS software. You can load a new level of the operating system in every router in your network and then, when convenient, upgrade the whole network to the new level.
Amounts of Memory
The Cisco 1721 router supports a maximum of 32MB Flash memory and 128MB DRAM. Use the show version command to view the amount of DRAM, NVRAM, and Flash memory stored in your router. The following example of the
show version command output displays the amount of memory in this router.
1721# show version
Cisco Internetwork Operating System Software
IOS (tm) C1700 Software (C1700-K9SY-M), Version 12.2(4)YA EARLY
DEPLOYMENT RELEASE SOFTWARE (fc1)
TAC Support: http://www.cisco.com/tac
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Mon 14-Jan-02 16:34 by ramesh
Image text-base: 0x80008108, data-base: 0x80BC77E8
ROM: System Bootstrap, Version 12.2(7r)XM1, RELEASE SOFTWARE (fc1)
1721 uptime is 4 days, 23 hours, 54 minutes System returned to ROM by reload
Running default software
| Cisco 1721 Router Hardware Installation Guide |
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