| 6.3 |  | Routing Protocols Overview |
| 6.3.3 |  | Routing protocols |

| At the Internet layer of the TCP/IP suite of protocols, a router can use an IP routing protocol to accomplish routing through the implementation of a specific routing algorithm. Examples of IP routing protocols include: RIP – A distance vector interior routing protocol IGRP – Cisco's distance vector interior routing protocol OSPF – A link-state interior routing protocol EIGRP – Cisco’s advanced distance vector interior routing protocol BGP – A distance vector exterior routing protocol Routing Information Protocol (RIP) was originally specified in RFC 1058. Its key characteristics include the following: It is a distance vector routing protocol. Hop count is used as the metric for path selection. If the hop count is greater than 15, the packet is discarded. Routing updates are broadcast every 30 seconds, by default. Interior Gateway Routing Protocol (IGRP) is a proprietary protocol developed by Cisco. Some of the IGRP key design characteristics emphasize the following: It is a distance vector routing protocol. Bandwidth, load, delay and reliability are used to create a composite metric. Routing updates are broadcast every 90 seconds, by default. Open Shortest Path First (OSPF) is a nonproprietary link-state routing protocol. The key characteristics of OSPF are as follows: It is a link-state routing protocol. Open standard routing protocol described in RFC 2328. Uses the SPF algorithm to calculate the lowest cost to a destination. Routing updates are flooded as topology changes occur. EIGRP is a Cisco proprietary enhanced distance vector routing protocol. The key characteristics of EIGRP are as follows: It is an enhanced distance vector routing protocol. Uses load balancing. Uses a combination of distance vector and link-state features. Uses Diffused Update Algorithm (DUAL) to calculate the shortest path. Routing updates are broadcast every 90 seconds or as triggered by topology changes. Border Gateway Protocol (BGP) is an exterior routing protocol. The key characteristics of BGP are as follows: It is a distance vector exterior routing protocol. Used between ISPs or ISPs and clients. Used to route Internet traffic between autonomous systems.
| Interactive Media Activity Checkbox: Link-State and Distance Vector Routing Protocols After completing this activity, the student will be able to understand IP routing protocols.
| Web Links Introduction to IP Routing http://www.cisco.com/en/US/tech/tk365/tech_topology _and_network_serv_and_protocol_suite_home.html