Cisco Router Hardware Software overview

In this lecture we will investigate an overview of Cisco router hardware and software. We will first turn our attention to the basic hardware components of a Cisco router. In this lecture we will investigate an overview of Cisco router hardware and software. We will first turn our attention to the basic hardware components of a Cisco router.

Basic Hardware Components Central Processing Unit (CPU) Central Processing Unit (CPU) Flash Memory Flash Memory Read-Only Memory (ROM) Read-Only Memory (ROM) Random-Access Memory (RAM) Random-Access Memory (RAM) Non-volatile RAM (NVRAM) Non-volatile RAM (NVRAM) Input/Output (IO) Ports and Media- Specific Converters Input/Output (IO) Ports and Media- Specific Converters

Central Processing Unit (CPU) The central processing unit (CPU), or microprocessor, executes instructions that make up the router’s operating system, as well as user commands entered via the console or via a Telnet connection. Thus, the processing power of the CPU is directly related to the processing capability of the router. The central processing unit (CPU), or microprocessor, executes instructions that make up the router’s operating system, as well as user commands entered via the console or via a Telnet connection. Thus, the processing power of the CPU is directly related to the processing capability of the router.

Flash Memory Flash memory is an erasable, reprogram able type of ROM memory. On many routers flash memory is an option that can be used to retain an image of the operating system and the router’s micro code Flash memory is an erasable, reprogram able type of ROM memory. On many routers flash memory is an option that can be used to retain an image of the operating system and the router’s micro code

Read-Only Memory (ROM) Read-only memory (ROM) contains code that performs power-on diagnostics similar to the power-on self-test (POST) many PCs perform Read-only memory (ROM) contains code that performs power-on diagnostics similar to the power-on self-test (POST) many PCs perform

Random-Access Memory (DRAM) Random-access memory (RAM) holds routing tables, performs packet buffering, furnishes an area for the queuing of packets when they cannot be directly output due to too much traffic routed to a common interface, and provides memory for the router's configuration file when the device is operational Random-access memory (RAM) holds routing tables, performs packet buffering, furnishes an area for the queuing of packets when they cannot be directly output due to too much traffic routed to a common interface, and provides memory for the router's configuration file when the device is operational

Non-volatile RAM (NVRAM) Non-volatile RAM (NVRAM) retains its contents when a router is powered off. By storing a copy of its configuration file in NVRAM Non-volatile RAM (NVRAM) retains its contents when a router is powered off. By storing a copy of its configuration file in NVRAM

Input/Output (IO) Ports and Media-Specific Converters The input/output (I/O) port is the connection through which packets enter and exit a router The input/output (I/O) port is the connection through which packets enter and exit a router

The Router Initialisation Process

Basic Software Components

Operating System Image IOS The operating system image consists of a series of routines that supports the transfer of data through the device, manages buffer space, supports different network functions, updates routing tables, and executes user commands. The operating system image consists of a series of routines that supports the transfer of data through the device, manages buffer space, supports different network functions, updates routing tables, and executes user commands.

Configuration File This file is created by the router administrator and contains statements interpreted by the operating system that tell it how to perform different functions built into the OS This file is created by the router administrator and contains statements interpreted by the operating system that tell it how to perform different functions built into the OS Once the configuration file is saved, it is stored in the NVRAM and loaded into upper-addressed memory each time the router is initialised Once the configuration file is saved, it is stored in the NVRAM and loaded into upper-addressed memory each time the router is initialised

The Router Configuration Process

The first time you take a router out of the box and power it on, or after you add one or more hardware components, you must use the setup command The first time you take a router out of the box and power it on, or after you add one or more hardware components, you must use the setup command

Cabling Considerations The system console port on a router is configured as a data terminal equipment (DTE) port The system console port on a router is configured as a data terminal equipment (DTE) port A crossover cable is needed, where pin 2 at one end is crossed to pin 3 on the other end and vice versa A crossover cable is needed, where pin 2 at one end is crossed to pin 3 on the other end and vice versa

Console Access A variety of communications programs are available for accessing the router via its console port. Since Windows95 and Windows98 include the HyperTerminal communications program A variety of communications programs are available for accessing the router via its console port. Since Windows95 and Windows98 include the HyperTerminal communications program

Setup Considerations The Command Interpreter The Command Interpreter Referred to as the EXEC Referred to as the EXEC user and privileged modes user and privileged modes

User EXEC mode = “>” prompt When you log into the router, you are in the user command mode where the system prompt appears as an angle bracket (>). When you log into the router, you are in the user command mode where the system prompt appears as an angle bracket (>). By logging into the router, you access user EXEC commands that allow you to connect to another host, provide a name to a logical connection, change the parameters of a terminal, display open connections, and perform similar operations that are not considered critical operations by Cisco Systems. By logging into the router, you access user EXEC commands that allow you to connect to another host, provide a name to a logical connection, change the parameters of a terminal, display open connections, and perform similar operations that are not considered critical operations by Cisco Systems.

USER MODE OPERATIONS

Privileged EXEC mode Accessed by “enable” command and or password. Accessed by “enable” command and or password. “#” prompt indicates you are at the privileged mode “#” prompt indicates you are at the privileged mode Allows the following features Allows the following features

Privileged EXEC mode “#”  configuration information,  configuration information,  turn privileged commands on or off,  turn privileged commands on or off,  lock the terminal, and  lock the terminal, and  perform other critical functions.  perform other critical functions.

Configuration Command Categories Configuration commands can be categorized into four general categories: (1) global, which defines system wide parameters; (1) global, which defines system wide parameters; (2) interface, which defines WAN or LAN interfaces; (2) interface, which defines WAN or LAN interfaces; (3) line, which defines the characteristics of a serial terminal line; and (3) line, which defines the characteristics of a serial terminal line; and (4) router subcommands, which are used to configure a routing protocol. (4) router subcommands, which are used to configure a routing protocol.

GLOBAL CONFIGURATION COMMANDS Global configuration commands are used to define system wide parameters, including access lists. Global configuration commands are used to define system wide parameters, including access lists.

INTERFACE COMMANDS define the characteristics of a LAN or WAN interface and are preceded by an interface command. define the characteristics of a LAN or WAN interface and are preceded by an interface command. interface serial 0 interface serial 0