说明ccna共享22-eigrp理论

1、CCNA (640-802) CCNA 200-120 灵活的网络设计组播和单播代替广播更新在网络中任何地方实现手动汇总 100% 无环路的无类路由支持 WANs and LANs等价和非等价负载均衡高级距离矢量协议快速收敛支持 VLSM 和不连续的子网局部更新支持多种网络层协议EIGRP 特征EIGRP 关键技术邻居发现使用hello包发现邻居可靠传输协议 (RTP)保证EIGRP的包到达所有的邻居DUAL 弥散更新算法Selects lowest-cost, loop free, paths to each destination协议独立模块 (PDMs)EIGRP 支持 IP, Appl

2、eTalk和 Novell NetWare.每一种网络协议支持EIGRP都有自己独立的模块EIGRP Neighbor TableEIGRP Topology TableEIGRP IP Routing TableExample: EIGRP TablesRouter C Tables:DUAL Terminology对于每个目标网段选择一条最低开销并且无环路的路径AD =下一跳路由器到目标网段的COSTFD = 本地路由器的开销 = 下一跳路由器的AD + 本地路由器到下一跳路由器的COSTLowest-cost = 最低的 FD(Current) successor = COST值最低并且

3、无环路的下一跳路由器Feasible successor = 无环路的备用路由器 (feasible successor 的AD必须小于当前的successor的FD)Example: DUAL of EIGRP10010201010010010020101020ABEJCFGDHIEIGRP PacketsHello: 建立邻居关系.Update: 发送路由更新信息.Query: 向邻居发送的请求查询信息.Reply: 用来响应Query信息.ACK: 确认一个可靠的报文.Initial Route DiscoveryEIGRP MetricSame metric components as

4、 IGRP:Bandwidth（带宽）Reliability（可靠性）Delay（延迟）Loading（负载）MTU（最大传输单元）EIGRP metric is IGRP metric multiplied by 256.EIGRP Metric CalculationBy default, EIGRP metric:Metric = bandwidth (slowest link) + delay (sum of delays)Delay = sum of the delays in the path, in tens of microseconds, multiplied by 256B

5、andwidth = 107 / (minimum bandwidth link along the path, in kilobits per second) * 256Formula with default K values (K1 = 1, K2 = 0, K3 = 1, K4 = 0, K5 = 0):Metric = K1 * BW + (K2 * BW) / (256 load) + K3 * delayIf K5 not equal to 0:Metric = metric * K5 / (reliability + K4):A B C D Least bandwidth 64 kbps Total delay 6,000 A X Y Z D Least bandwidth 256 kbps Total delay 8,000Delay is the sum of all the delays of the links along the paths:Delay = delay in tens of microseconds x 256Bandwidth is the lowest bandwidth of the links along the paths:Bandwidth = 10,000,000 /