1 Introduction to Routers Nasir Majeed Assistant Professor PTCL Academy Islamabad

2  Function of a Router  Components of a Router  Router Boot-up Process

3  Routing is the process of moving information (data packets) from one network to another network using routers  Routers are used to direct packet to its destination  Routers examine a packet’s destination IP address and determine the best path by using routing table

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5  Random Access Memory (RAM)  Non-Volatile RAM (NVRAM)  Flash Memory  Read-Only Memory (ROM)  Console  Interfaces

6 RAM  Loses content when router is powered down or restarted  Provides temporary memory for the configuration file of the router while the router is powered on  Stores routing tables  Holds ARP cache  Holds fast-switching cache  Performs packet buffering (shared RAM) NVRAM  Retains content when router is powered down or restarted  Provides storage for the startup configuration file

7 Flash Memory  Retains content when router is powered down or restarted  Holds the operating system image (IOS)  Allows IOS to be updated without removing and replacing chips  Can store multiple versions of IOS software ROM  Stores instructions for power-on self test (POST) diagnostics  Stores bootstrap program  Stores basic operating system software  Requires replacing chips on the motherboard for software upgrades Console Port  Used to configure the router

8 Components of a Router

9 Interfaces  Router Interface is a physical connector that enables a router to send or receive packets  Each interface connects to a separate network  Consist of socket or jack found on the outside of a router  Can be on the motherboard or on a separate module  Types of router interfaces:  Ethernet or FastEthernet  Serial  DSL  ISDN (BRI or PRI)  Others

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