First, the algorithm: algorithm迪捷科思特拉
Two, OSPF Features
1, CIDR
2, the convergence speed: relative RIP fast convergence with respect to EIGRP slower
3, is a classless routing protocol support: VLSM , CIDR , discontinuous subnets, manual tabulation
4, support for zoning
5, supports authentication
(1) No authentication ( 0 )
(2) a simple plain text authentication ( 1 )
(. 3) the MD5 Authentication ( 2 )
6, triggered updates
. 7, the OSPF is an acyclic protocol (limited to the area): in an area absolute acyclic, because based on SPF algorithm
. 8, the OSPF underlying protocol: the IP 89
. 9, the OSPF priority of 10 (inside the OSPF ), 150 (outside the OSPF )
10, the OSPF using the overhead ( cost ) for the metric
11, OSPF multicast updates ( 224.0.0.5 , 224.0.0.6 )
12, OSPF of three tables:
(1) neighbor (neighbor database)
(2) the topology table (link state database the LSDB )
(3) the routing table ( the RIB )
13 is, the LSDB every 30 minutes updated once ( the LSA , 1800 sec), 60 minutes ( 3600 seconds) Aging
14, OSPF process number only local significance
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. 1, the LSA (link status information): status information about each link
(1) Link: an interface declaration into OSPF
(2) Area:
(3) Autonomous System ( the AS ): AS is the use of a set of a routers exchange routing information of the same routing protocol.
2, the LSU (link state update packets): comprising the LSA information
3, the shortest path algorithm ( SPF algorithm)
4, the neighbor relationship: neighbor relationship is a necessary step in establishing an adjacency
5, adjacency
6, the specified route, is ( the DR )
7, backup designated router ( BDR )
8, non-designated router ( DRother )
. 9, Router ID : autonomous system for uniquely identifies a running OSPF routers 32 -bit integer, each running OSPF routers have a Router ID .
(1) can be specified in the global : router-id
(2) can be OSPF designated under process: ospf 1 Router the above mentioned id 1.1.1.1
(3) the process is better than the global
(4) If no Router-the above mentioned id , automatically elections :
① relatively large logical interface address
② logical interface superior physical interface
③ If no logical interface, the choice of the physical interface
(5) the sequence:
① priority manually assigned
② automatic election, the Loopback mouth big advantage
③ physical interface big advantage
11, internal router ( Internal Router ):
内部路由器是指所有所连接的网段都在一个区域的路由器。属于同一个区域的IR维护相同的LSDB。
12、区域边界路由器（Area Border Router）：
区域边界路由器是指连接到多个区域的路由器。ABR为每一个所连接的区域维护一个LSDB。
13、骨干路由器（Backbone Router）：
骨干路由器是指至少有一个端口（或者虚连接）连接到骨干区域的路由器。包括所有的ABR和所有端口都在骨干区域的路由器。
14、AS边界路由器（AS Boundary Router）：
AS边界路由器是指和其他AS中的路由器交换路由信息的路由器，这种路由器向整个AS通告AS外部路