Router

A router is a device that determines the next network point to which a packet should be forwarded toward its destination. A router must be connected to at least two networks.

A router creates and/or maintains a table, called a routing table that stores the best routes to certain network destinations and the metrics associated with those routes.

There are several manufacturers of routers including

• [Ascend Communications]? (http://www.ascend.com)
• Cabletron? (http://www.cabletron.com)
• [Cisco Systems]? (http://www.cisco.com)
• 3Com (http://www.3com.com)
• [Pivotal Networking]? (http://www.pivnet.com )
• [Juniper Networks]? (http://www.juniper.net)
• Linksys? (http://www.linksys.com)
• [D-Link Systems]? (http://www.dlink.com)

A routing protocol is the method by which a router determines the best path to the destination. Exterior Gateway Protocols (EGPs) are used for routing between autonomous systems. EGPs include:

• BGP (Border Gateway Protocol)

Interior Gateway Protocols (IGPs) route data within an autonomous system. IGPs include:

• IGRP/EIGRP (Interior Gateway Routing Protocol/ Enhanced IGRP)
• OSPF (Open Shortest Path First)
• RIP (Routing Information Protocol)