Cisco 2511 - Router - EN Instrukcja Użytkownika Pobierz pdf (Strona 6)

• Interfaces – These are the network connections through which

packets transverse the router. Multiple interfaces can reside on the

same motherboard or they can be on separate interface modules. The

console and auxiliary ports are examples of the router interfaces. The

console port is the asynchronous data port for the direct terminal

access to the router. Remote router access can be provided by a

modem connection to the aux port. The aux port can also be used for

WAN connection.

Memory

The Cisco Routers have four types of memory:

• ROM (Read Only Memory) – ROM contains power-on diagnostics,

the bootstrap program, and the operating system software loader.

• RAM (Random Access Memory) – RAM is for storing routing tables,

the ARP cache, fast-switching caches, and packet queuing and

buffering. This memory provides temporary (or Running) memory

for the router’s configurations while the router is powered on. When

the router is powered off, all the data in the RAM, including the

running configuration and routing tables, will be cleared.

• NVRAM (Nonvolatile RAM) – This is where the router’s

configurations are saved. As this would suggest, the NVRAM content

is retained when you power down or reboot the router.

• Flash (Erasable, Programmable ROM) – Flash memory holds the

operating system image (Cisco IOS Software) and macrocodes. Using

flash memory allows you to update software without removing or

replacing chips on the processor. Flash contents are retained when

you power down or reboot the router.

3. Introduction to Cisco IOS

To connect to the router you need to execute Cisco Internetworking

Operating System (IOS®) commands. Cisco IOS® is a software that runs on

all Cisco routers and allows the user to manage and configure the processes

that occur on the router. Cisco IOS is command-line interface (CLI)

software which accepts user commands and displays router output.

As a security feature, Cisco IOS provides separate commands into two

different access level modes; user EXEC level; permits limited number of

commands, and privileged EXEC level; allows the execution of all

commands:

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Cisco 2511 - Router - EN Instrukcja Użytkownika Strona 6