ROUTER-BASICS

CISCO 2801 Router

Netgear Router

Router:

Router is an inter-networking component, that connects networks which are at different geographical locations.

Types of Routers : 

Modular Routers (CISCO Routers) These type of routers have up gradable slots, and the number of ports can be increased just by adding cards in the slots.

Fixed Routers (Netgear, Dlink, Tplink) These types of routers have fixed number of ports.

Cisco Router’s Series

Cisco 700, 800, 1600, 1700, 2500, 2600, 3600, 4000, 5000, 7000,10000, 12000.

• Fixed Routers (700,800....2500)
• Modular ( 2600....12000)

1750 & 1751 exceptionally are Modular Routers.

Cisco’s Hierarchical Model

Interfaces on a Router

• Ethernet It is a LAN interface. Some of the models have an RJ45 port for 10baseT or 10/100. And some other have a 15 pin female connector AUI (Attachment Unit Interface).
• Serial It is a 60 pin female WAN interface for leased line
• BRI/PRI It is a RJ45 WAN interface for ISDN
• Async It is a 37 pin female connector for dial ups.
• Console It is a RJ45 Connector used to configure the router for the first time.
• Auxiliary RJ45 Connector for remote access administration.

Internal components of a router

Boot ROM : It stores the mini IOS (Internet work Operating System) image (RX Boot) with extremely limited capabilities and POST routines  and core level OS for maintenance.

FLASH : It is an EPROM chip that holds most of the IOS Image. It maintains everything when router is turned off.

RAM : RAM holds running IOS configurations and provides caching. RAM is a volatile memory and looses its information when  router is turned off. The configuration present in RAM is called Running configuration.

NVRAM : It is a re-write able memory area that holds router’s configuration file. NVRAM retains the information when ever router is rebooted. Once configuration is saved, it will be saved in NVRAM and this configuration is called Startup Configuration.

Configuration of a Router

     Router for the first time is configured through the CONSOLE port.COM port of a PC is connected to the console port of router with a console cable by using a transceiver. Router is accessible by a tool. In windows, it is called HYPER TEMINAL. As soon as the router is powered on and accessed, the following things happen..

In Setup mode, there will be a message,

“Would You Like To Enter The Initial Configuration [Y/N]” :

If “Y” then, initial configuration starts.

If “N” would you like to terminate the auto installation?

Press “RETURN” to get started……You will land on the default prompt of the Router “ ROUTER >”.

Router>_