Fourth Chapter Dynamic routing protocol

 4.1 routing protocol The underlying routing algorithm should indicate the content:    * Process of transmitting network-accessible information to other routers     * Process of receiving information from other routers     * Based on the process of the optimal routing of reachable information decision and the process of recording these information in the routing table     * response, correcting and informing the process of topology change in the network  4.1.1 path decision  4.1.2 Metric when there are multiple routes that reach the same target segment, The router needs a mechanism to calculate the optimal path, and the metric metric is a variable assigned to the route. 1. Hop count hop counts to simply record the number of hops in the route. 2. Bandwidth bandwidth bandwidth will select a high bandwidth path. 3. Load load reflects the amount of link bandwidth that the traffic occupies along the way, and the optimal path should be the least loaded path. 4. Shiyan Delay is the world 5 that a measurement datagram spends on a path. Reliability Reliability measurement is a measure of the likelihood that a link will fail in a certain situation, which can be variable or fixed. 6. Cost-cost cost 4.1.3 convergence routing loop routing loop convergence of traffic between two or more target networks convergence the process of bringing all routing tables to a consistent state     Convergence time: Information sharing across the entire network and the sum of time spent in calculating the optimal path for all routers     faster convergence the better  4.1.4 load balancing distributes traffic to multiple paths on the same target network segment  4.2 Distance vector routing protocol distance vector algorithm called Bellman-ford or Ford-fulkerson algorithm EIGRP is based on J.J Garcia Luna aceves Development Distance Vector Routing protocol: rip,eigrp 4.2.1 General properties A typical distance vector routing protocol chooses a routing algorithm in which routers send routing update information to all neighbors on a regular basis by broadcasting the entire routing table 1. Regular updates to periodic updates periodically mean that updates are sent for each specific time period. This cycle is from 10s to 90s 2. A neighbor neighbours neighbor means a router that shares the same data link or a higher-level logical adjacency relationship  3. Broadcast Update broadcast updates when the router is first activated, The router sends update information to the broadcast address, and the neighbor router that uses the same routing protocol receives the broadcast datagram and takes the appropriate action.  4. Full routing table update most distance vector routing protocols use the routing table broadcast to tell the neighbor what it knows  4.2.2 route selection according to rumors  4.2.3 Each table entry in the Routing Failure Timer routing table sets a typical period of time when the route expiration Timer Route timeout is 3-6 cycles  4.2.4 horizontal split. To be continued              

Fourth dynamic routing protocol