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Chapter 10 - Link-State Routing Protocols CCNA Exploration 4.0 1 Objectives • • Describe the basic features & concepts of link-state routing protocols. List the benefits and requirements of link-state routing protocols. Học viện mạng Bach Khoa - Website: www.bkacad.com 2 Introduction Học viện mạng Bach Khoa - Website: www.bkacad.com 3 Link-State Routing Học viện mạng Bach Khoa - Website: www.bkacad.com 4 Link-State Routing • Link state routing protocols – Also known as shortest path first algorithms. – These protocols built around Dijkstra’s SPF. Học viện mạng Bach Khoa - Website: www.bkacad.com 5 Link-State Routing • Dikjstra’s algorithm also known as the Shortest Path First (SPF) algorithm. This algorithm accumulates costs along each path, from source to destination. Học viện mạng Bach Khoa - Website: www.bkacad.com 6 Link-State Routing • The shortest path to a destination is not necessarily the path with the least number of hops. Học viện mạng Bach Khoa - Website: www.bkacad.com 7 Link-State Routing • How routers using Link State Routing Protocols reach convergence – Each routers learns about its own directly connected networks – Link state routers exchange hello packet to “meet” other directly connected link state routers. – Each router builds its own Link State Packet (LSP) which includes information about neighbors such as neighbor ID, link type, & bandwidth. – After the LSP is created the router floods it to all neighbors who then store the information and then immediately forward it until all routers have the same information. – Once all the routers have received all the LSPs, the routers then construct a topological map of the network which is used to determine the best routes to a destination. Học viện mạng Bach Khoa - Website: www.bkacad.com 8 Link-State Routing • • • Directly Connected Networks. Link: this is an interface on a router. Link state: this is the information about the state of the links. Học viện mạng Bach Khoa - Website: www.bkacad.com 9 Link-State Routing • Routers with link-state routing protocols use a Hello protocol to discover any neighbors on its links. A neighbor is any other router that is enabled with the same link-state routing protocol. Học viện mạng Bach Khoa - Website: www.bkacad.com 10