OSPF融合
网络收敛是拓扑更改后同步网络转发表的过程。请清楚地解释一下OSPF收敛的步骤以及它比RIP收敛如何更好？
Network convergence as the process of synchronizing network forwarding tables after a topology change.Please can some explain clearly what are the steps in OSPF Convergence and how is it better than RIP Convergence ?
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OSPF是链路状态算法（它使用Dijkstra的最短路径算法），因此具有整个网络的视图。这可确保网络中的每个路由器了解完整的网络拓扑，并可以决定使用哪些路由到不同的目的地（子网）。 OSPF 的收敛依赖于 OSPF 计时器（为了更好地理解 http:// www2.ensc.sfu.ca/~ljilja/cnl/pdf/hubert.pdf，其中包含有关收敛测试的详细信息）。
RIP是一种距离矢量协议，距离矢量存在计数到无穷大的问题。 RIP 使用网络直径概念来避免这个问题。 RIP 中的最大网络直径可以为 15，因此跳数（RIP 中距离的度量）限制为 15，这可以避免计数无穷大问题。因此，RIP 的收敛性（在最坏的情况下）等于网络直径，或者准确地说是 15。
希望这有帮助。
OSPF is link-state algorithm (it uses Dijkstra's shortest path algorithm) hence has the view of entire network. This ensures that every router in the network know the full network topology and can decide which routes to use to different destinations (subnets). Convergence of OSPF is dependent on OSPF timers (for better understanding http://www2.ensc.sfu.ca/~ljilja/cnl/pdf/hubert.pdf , this has details on convergence tests).
RIP is a distance vector protocol and distance vector has count-to-infinity problem. RIP uses network diameter concept to avoid this problem. The maximum network diameter can be 15 in RIP hence hop count (measure of distance in RIP) is limited to 15 and this avoids count-to-infinity problem. Convergence of RIP is hence (in worst case) equal to network-diameter or 15 to be precise.
Hope this helps.
OSPF 收敛通过以下方式进行
1-路由器身份首先被发现，它通过以下方式发生
a) 使用路由器活动环回接口上的最高 IP 地址
b) 如果不存在环回接口，则路由器启动时将使用其活动接口上的最高 IP 地址。
2-下一步 找出邻居关系 - OSPF 路由器了解其 OSPF 邻居，并通过共享 LSA 构建其邻接表和拓扑表。2 个 OSPF 路由器相互连接的条件
a)2个路由器的区域号必须相同
b) 两个路由器的 hello 和 dead 定时器必须相同
c) 两者的OSPF密码必须相同
d) 两个接口上的 MTU 大小必须相同
邻居是通过称为交换过程的过程形成的
1-Down 状态-没有交换 ospf 信息
2-Init State-收到另一台路由器的LSA hello数据包
3-2way状态-已发生单向回复。
3-选举指定和备份指定路由器 - 具有最高优先级的路由器成为该网段的 DR，如果存在平局，则具有最高 RouterID 的路由器将成为 DR，第二高的 IP 地址将成为 BDR。
希望这有帮助
OSPF convergence takes place in the following ways
1-Router Identities are first found out , it happens in the following ways
a)The highest IP address on the router's active loopback interfaces is used
b)If no loopback interface is present the highest IP address on its active interfaces is used when the router boots up.
2-Next Step Negihbour relationships are found out-An OSPF router learns about its OSPF neighbours and builds its adjacency tables and topology tables by sharing LSA's.Criteria for 2 OSPF routers to be connected to each other
a)The area number of the 2 routers must be the same
b)The hello and dead timers for both the routers must be the same
c)The OSPF password on both of them must be the same
d)MTU sizes on both the interfaces must be the same
Neighbours are formed by the process known as exchange process
1-Down State-No ospf info exchanged
2-Init State-Another router's LSA hello packet is recieved
3-2way state-Unidirectional reply has taken place.
3-Electing designated and BackupDesignated routers- Router with the highest priority becomes the DR for the segment,If there is a tie the router with the highest routerID will become the DR,the second highest IP address becomes the BDR.
Hope this helps
假设您要开车去伦敦市。突然有一个路障。
用户 OSPF 拥有完整的伦敦城市地图（拓扑）
用户RIP仅依赖于各个路口的警察交通信号和标志牌。 （仅下一跳信息）
当遇到路障、交通拥堵等情况时，哪个用户会更快到达目的地？
Suppose you go to driving to London City. Suddenly there is a road block.
User OSPF have the full london city map (topology)
User RIP only depend on Police traffic signal and sign board at various junction. (only next hop information)
Which user will reach his destination faster in the event there is road block, traffic jam etc.