I. Introduction of Cisco Router
IOS configured by all Cisco routers is an embedded software architecture.
Like ordinary computers, routers need an operating system. Cisco calls this operating system Cisco Internet Operating System, also known as IOS.
Cisco IOS software provides the following network services: extensible network structure, basic routing and switching functions, and reliable and secure access to network resources. Cisco Command Line Interface (CLI) adopts hierarchical structure and needs to complete specific tasks in different modes. For example, to configure an interface of a router, the user must enter the interface configuration mode of the router, and all configurations will only be applied to this interface. Each different configuration mode has a specific command prompt. EXEC provides command interpretation service for IOS software. When each command is typed, EXEC will execute it.
Second, the configuration of Cisco router
When configuring a Cisco router for the first time, we need to configure it from the console port. Here's how to connect to the control port and set up the virtual terminal program:
(1) Connect the router control port and the terminal computer with the rollover cable and the conversion adapter between RJ45 and DB9 or DB25. How to connect the control port of Cisco router: Control port and auxiliary port are two management ports of Cisco router. When configuring a Cisco router for the first time, both ports can be used, but we generally recommend using the control port because not all routers have AUXport.
(2) When the router is started for the first time, there are no network parameters by default, and the router cannot communicate with any network. So we need an RS-232ASCLL terminal or a computer simulation ASCLL terminal to connect the control port.
(3) the method of connecting to the console port
Connecting cables: To connect to the console port, we need a flip cable and an RJ-45 to DB-9 adapter. We can generally see it in the product accessories of Cisco routers.
Terminal emulation software: PC or terminal must support VT 100 emulation terminal. Usually, we use HyperTerminal software in WindowsOS environment. Here, let's take the hostname riga as an example, enter the hostname riga in global mode, and then press enter to execute the command. At this point, the host name in front of the host prompt changes to Riga, indicating that the host name is set successfully.
3. Enter Cisco router configuration mode.
The command line port of Cisco router adopts hierarchical structure, and it needs to log in to different modes to complete detailed configuration tasks. From a security point of view, Cisco IOS software divides the execution session into user mode and privileged mode.
Fourth, the characteristics of the privilege model.
Privileged mode can use all configuration commands. In user mode, access to privileged mode usually requires a password, and the command prompt of router# indicates that the user is in privileged mode.
Verb (abbreviation of verb) The characteristics of user mode.
Only basic monitoring commands are allowed in user mode, and Cisco router > configuration cannot be changed in this mode. The command prompt of indicates that the user is in user mode.
Six, Cisco router configuration mode
User mode usually only allows users to display router information without changing any Cisco router configuration. If you want to use all commands, you must enter privileged mode. In privileged mode, you can also enter global mode and other special configuration modes, which are subsets of global mode.
Seven. Privileged mode
At the first successful startup, the user mode prompts router >；; . If you want to enter privileged mode, type the enable command (no password is required to start the router for the first time). At this point, the command prompt of the router becomes router#.
VIII. Global model
After entering privileged mode, we can enter global configuration mode by typing the configureterminal command at the privileged command prompt.
Nine, port configuration mode
Type interfacee0 at the global command prompt to enter the first Ethernet port, and type interfaceserial0 to enter the first serial line port. The above briefly introduces how to enter various configuration modes of Cisco routers. Of course, you can also enter other special configuration modes in global mode. During the configuration process, we can use? Get command help.
X.Cisco router configuration password
In Cisco router products, we usually need to restrict the access of ordinary users at the initial configuration. This is very important for Cisco router configuration. By default, our router is an open system, and the access control options are all turned off, so any user can log in to the device for further operation. Therefore, our network administrator needs to configure passwords to restrict unauthorized users from accessing devices through direct connections, console terminals and dial-up modem lines. The following details how to configure the router password on Cisco router products.