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1、 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 特征特征EIGRP 关键技术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,AppleTalk和 Novell NetW
2、are.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值最低并且无环路的下一跳路由器Feasible successor=无环
3、路的备用路由器(feasible successor 的AD必须小于当前的successor的FD)Example:DUAL of EIGRP10010201010010010020101020ABEJCFGDHI10.10.10.10EIGRP 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 IGRP:Bandwidth（带宽）Reliabilit
4、y（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 256Bandwidth=107/(minimum bandwidth link alo
5、ng 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 8,000 Delay is the sum of all the delays of the links along the paths:Delay=delay in tens of microseconds x 256 Bandwidth is the lowest bandwidth of the links along the paths:Bandwidth=10,000,000/(bandwidth in kbps)x 256EIGRP Metrics Calculation ExampleEIGRP Metrics Are Backward-Compatible with IGRP
CISCO网络技术：19、EIGRP理论
