ZyXEL XGS4700-48F User Guide - Page 329
OSPF Overview
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CHAPTER 36 OSPF This chapter describes the OSPF (Open Shortest Path First) routing protocol and shows you how to configure OSPF. 36.1 OSPF Overview OSPF (Open Shortest Path First) is a link-state protocol designed to distribute routing information within an autonomous system (AS). An autonomous system is a collection of networks using a common routing protocol to exchange routing information. OSPF offers some advantages over traditional vector-space routing protocols (such as RIP). The following table summarizes some of the major differences between OSPF and RIP. Table 112 OSPF vs. RIP OSPF Network Size Large Metrics Bandwidth, hop count, throughput, round trip time and reliability. Convergence Fast RIP Small (with up to 15 routers) Hop count Slow 36.1.1 OSPF Autonomous Systems and Areas An OSPF autonomous system (AS) can be divided into logical areas. Each area represents a group of adjacent networks. All areas are connected to a backbone (also known as area 0). The backbone is the transit area to route packets between two areas. A stub area, at the edge of an AS is not a transit area since there is only one connection to the stub area. XGS4700-48F User's Guide 329
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