OSPF sử dụng thuật toán Dijkstra, mà xuất phát từ các chi nhánh của toán học được gọi là lý thuyết đồ thị, để tính toán con đường chi phí thấp nhất để một điểm đến từ một nguồn nhất một khách hàng WINS khởi động, nó sẽ đăng ký tên NetBIOS của nó với một máy chủ WINS cấu hình thông qua một "Yêu cầu đăng ký tên NetBIOS." | 566 Chapter 11 Troubleshooting Windows 2000 Connectivity Problems at the Internetwork Level networks such as ATM or . OSPF has different protocols for broadcast and multicast network types. NOTE OSPF uses the Dijkstra algorithm which comes from the branch of mathematics known as graph theory to calculate the lowest-cost path to a destination from a given source. OSPF on a Broadcast Network On a broadcast network OSPF uses a packet called a Hello protocol message which is a broadcast message by which routers locate one another. A router is selected to be the Designated Router DR and all the other routers exchange routing information with the DR. Then the DR updates neighboring routers. The DR is elected by an exchange of Hello packets. Each packet includes the current DR the sending router s router ID and its router priority which can be set during configuration of OSPF . The router with the highest priority is selected to be the DR. If more than one router has the same priority the one that has the highest router ID will become the DR. A backup DR is also elected for multiaccess networks so if the DR becomes unavailable connectivity will not be lost. WARNING__ Configuring an OSPF router with a priority of 0 means it cannot become a DR. There must be at least one router on the multiaccess network that has a priority of 1 or above. Otherwise no router can become DR and the link state database cannot be synchronized resulting in no traffic being passed across that network. OSPF on a Nonbroadcast Network On a network using a nonbroadcast architecture such as ATM OSPF has to be initially configured manually with the addresses of neighboring routers. A DR is also used but rather than sending the routing information via broadcast or multicast it is sent point to point between the DR and the other routers. This means a greater number of virtual
