Cisco - Router Architecture

Router Hardware Architecture

Some of the components that comprise a Cisco router include:

RAM/DRAM—Random-access memory/dynamic random-access memory. The main information-storage component in the router, RAM/DRAM contains the running configuration information.

NVRAM—Nonvolatile RAM. This information-storage component contains a backup copy of the configuration. If power is lost or the router is turned off for a period of time, the router boots from the backup copy of the configuration.

Flash memory (also called Flash)—A special kind of nonvolatile information storage that can be electrically erased and reprogrammed. This memory contains copies of the Cisco IOS software. Flash can store multiple copies of the IOS™ software, allowing you to load a new version of the IOS software on every router in your network and then, at some convenient time, upgrade the whole network to that version.

ROM—Read-only memory. This memory contains an initializing bootstrap program and a small monitoring system that can be used to recover from a catastrophe.

Interfaces—These are the network connections through which network traffic enters and exits the router. Cisco routers support a great variety of interfaces, including Ethernet, Token Ring, and serial.

Console and Auxiliary Ports—These are connections used to attach the router to a terminal, a PC running terminal-emulation software, or a modem, allowing configuration commands to be entered.


Chapter Basic Router operation

1. starting up a router
2. accessing the user interface
3. examining router status
4. exercise: router commands
5. Lab: Using the user Interface
6. Exercise Answer




Chapter Configuring a router

1. Loading configuration files
2. Router Modes
3. Managing the configuration environment
4. Lab: configuring a router
5. LAb: managing the configuration Environment
6. Exercise Answer




Exernal configuration Sources

you can configure the router
1. Console terminal via console port
2. Modem via auxillary port
3. Interface (Virtual terminals, TFTP, Network Management Stations)
3a. Vertual terminals 0-4 once the router is install on the network
3b. configuratoin information can be download from a tftp server on the network
3c. manager router configration from a remoter system running network management such as CiscoWorks or HP openview

Note to send and recieve configration information to and from a vertual terminal, TFTP server or networkmagment station, the router must be configure to support IP traffic



Internal Configuration components

1. RAM - main storage component for the router, its call working storage and contains dymanic configuration inforation

2. NVRAM - nonvolite RAM can contains backup copy of your configuration, if power is lost the backup copy of configuration            enable the router to return to operation without needing to be reconfigured

3. FLASH - Erasable programmable read-only memory. It contains a copy of Cisco Internetwork Operating System (Cisco IOS). It is structured to store multiple copies of Cisco IOS software, alloowing you to load the new level of OS in every router in your network and then at some convient time , to upgrade the whole network to the new level

4. ROM - Contains an initializing bootstrap program and a small monitoring system that can be used to recover from a catastrophe

5. interfaces - These are network connections through which packets enter and exit the router. cisco supports a avarity of interfaces, including Ethernet, token Ring, serial

6. Console and Auxillary ports  - the console is the main line inerface control mechanism for the router. Auxillary port also can be used for configuration. both the console and auxiliary port support asynchronous TTY lines.


An overview of System Startup

1. Check hardware
2. Find and load Cisco IOS software image that the router use for its operating system
3. Find and apply router configuration information about router specific attribues, protocol functions and interface addresses.


system startup routines initiate router software
fallback routines provide startup anternatives as needed





Note the following

Router Modes
User Exec mode  Router>
prilivage Exec mode Router#
Global configure mode Router(config)#

other Configure mode
interface   Router(config-if)#
subinterface Router(config-subif)#   - supports mulit vertual interfaces
controller  Router(config-controller)# support connands taht configure channelized T1
line  Router(config-line)#  supports commands that configure the operation of a terminal line
router Router(config-router)# supports commands that configure an IP routing protocol
ixp-router Router(config-ipx-router)# supports commands that configure the novell network layer protocol
route-map Router(config-route-map)# supports commands that configure routing table with source and destination information




router#configure terminal - puts you in global Configure mode
Router(config)#


Router(config)#interface serial 1
Router(config-if)#  - Puts you in specific interface


Password Configuration

Console password (for console terminal)
Router(config)#line console 0
Router(config-line)#login
Router(config-line)#password cisco


Vertual terminal password (for telnet sessions)
Router(config)#line vty 0 4
Router(config-line)#login
Router(config-line)#password sanjose


Enable password (restrict access to privilage exec mode)
Router(config)#enable password cisco


Enable secret password
Router(config)#enable secret sanfran



Boot system options in Software

1. FLASH
Router#configure terminal
Router(config)#boot system flash c2500-js-l
[Ctrl-z]
Router#copy running-config startup-config


2. Network
Router#configure terminal
Router(config)#boot tftp test.exe 172.16.13.111
[Ctrl-z]
Router#copy running-config startup-config


3. ROM
Router#configure terminal
Router(config)#boot system ROM
[Ctrl-z]
Router#copy running-config startup-config