Router

=>it’s a WAN device, operate on network layer.=>its every port has its separate collision domain (full duplex) and broadcast domain.=>provide internetworking (connect different-different networks)=>path selection (always choose best and shortest path)=>packet forwarding (based on routing table)=>packet filtering (it can also filter user traffic using ACL (access-control list) tool)=>Support different type of WAN technologies (Ex: - DSL, Lease line, Frame Relay, ATM, ISDN, MPLS)=>types of cisco routera) Portable router: - We can change router port as per Requirement.b) Non-Portable router: - which having fixed numbers of port.

Cisco 2500

ROUTER PORTS

1) Console port: - Used for accessing cisco router/switch, for configuring purpose, default 9600 Bits per sec.

2) AUX (auxiliary port): - Same work as console port, but specially design for Dial-up modem configuration (speed variable).

3) Ethernet port: - Use for connect router with LAN network, we can also connect router to router.

1) Serial port (WAN Port): - Its use for connect router to router, and router to modem (speed 1.544 Mbps).

Serial port 60 PIN

Serial port

Cisco router series

Router to

Router to router

Cisco 1600

Cisco 2500

Cisco 3600

Cisco router component

Cisco 2800 Cisco 3800

Cisco IOS

=>Cisco IOS (originally Internetwork Operating System) is software used on most Cisco Systems routers and current Cisco network switches.(Earlier switches ran CatOS.) IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multi-tasking operating system.

=>Cisco first IOS was written by William Yeager in 1986 (language C)

=>Cisco IOS use .bin extension.

c2801-entbasek9-mz.124-(4).T1.bin

Release Format

Cisco IOS Software releases uses the format A.B(C) D, where: A, B, and C are numbers. D (if present) is a letter. A.B is a major release. C is the maintenance version. A higher maintenance number

means more bug fixes. Any feature, bug fix, and hardware support available in a particular maintenance version are also available in the next one.

D, if present, indicates that the release is not a major release, but an extension of a major release. These extensions usually provide new features and new hardware support.

Thus, in software release 12.2(7)T, 12.2 is the major release, 7 is the maintenance version, and T is the release extension

Cisco router mode

Base Command Modes Base command modes are used for navigating the CLI and performing basic router startup, configuration, and monitoring tasks.

User EXEC ModeThe EXEC commands available at the user EXEC level are a subset of those available at the privileged EXEC level. In general, the user EXEC commands allow you to connect to remote devices, change terminal settings on a temporary basis, perform basic tests, and list system information

Router>

Privileged EXEC ModePrivileged EXEC mode is password protected, and allows the use of all EXEC mode commands available on the system. To enter privileged EXEC mode from user EXEC mode, use the “enable” command

Router#

Global Configuration ModeGlobal configuration commands generally apply to features that affect the system as a whole, rather than just one protocol or interface. To enter global configuration mode, use the “configure terminal” privileged EXEC command.Router(config)#

Router boot process

The following details the router boot process: 1. Router is powered on.2. The bootstrap program (ROMmon) in ROM runs Power-On Self-Test (POST) 3. The bootstrap checks the Configuration Register value to specify where to load the IOS. By default (the default value of Configuration Register is 2102, in hexadecimal), the router first looks for “boot system” commands in startup-config file. If it finds these commands, it will run boot system commands in order they appear in startup-config to locate the IOS. If not, the IOS image is loaded from Flash. If the IOS is not found in Flash, the bootstrap can try to load the IOS from TFTP server or from ROM

(mini-IOS).4. After the IOS is found, it is loaded into RAM.5. The IOS attempts to load the configuration file (startup-config) from NVRAM to RAM. If the startup-config is not found in NVRAM, the IOS attempts to load a configuration file from TFTP. If no TFTP server responds, the router enters Setup Mode (Initial Configuration Mode).