EIGRP Metric 计算的理解^.doc

EIGRP Metric 计算的理解EIGRP Metric 计算的理解明天看了一个贴。EIGRP Metric 的计算。关于是用入向还是出站。1.EIGRP的度量值是沿着路由方向的路由器出站接口参数来计算的。2.沿着路由更新的入向接口来计算！你说是入向还是出站。以前作过。没去细细的做。没去实验过。马上实验。：全网通EIGRP。1.jpg (51.33 KB)2010-6-9 08:19R1.jpg (95.42 KB)2010-6-9 08:19R1.jpg (95.42 KB)2010-6-9 08:19R3.jpg (94.5 KB)2010-6-9 08:19R1：S1/1本来BW 1544 Kbit, DLY 20000 usec改为：R1(config-if)#bandwidth 500改完之后查看路由表：R1 2.jpg (80.14 KB)2010-6-9 08:19R1到已经变为一条路由了。R1#show ip eigrp topology IP-EIGRP Topology Table for AS(100)/ID()Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P /32, 1 successors, FD is 2809856 via (2809856/2297856), Serial1/0 via (6272000/2297856), Serial1/1R1从Serial1/1到的Metric已经变为：6272000。6272000=？-R1 3.JPG (52.25 KB)2010-6-9 08:19一做到这。发现问题了。Metric=(Bandwidth+Delay)*256 Bandwdth: 沿路由路径到目地的所有出站接口中带宽的最小值。 或：沿途更新入向接口的最小值。 107/Bandawdth Delay: 沿路由路径目地的出站接口的延迟总和和/10。 或：沿途更新入向接口的延迟总和和/10。原来是有前题的。R1.loopback0: MTU 1514 bytes, BW 8000000 Kbit, DLY 5000 usec,R1.S1/1: MTU 1500 bytes, BW 500 Kbit, DLY 20000 usecR4.S1/2: MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,= R1(S1/1).BW+R4(S1/2).delay+R1(S1/1).delay+R1(lo0).dylay*256=10000000/500+20000/10+20000/10+5000/10*256=6272000 验证：R3 2.jpg (82.29 KB)2010-6-9 08:19R3的路由表还是和改之前一样。说明R1。S1/1的改带宽对R3的建立路由表没影响。在这基础上再改R1（S1/1）.dylay20000改为：200000R1#show ip eigrp topology IP-EIGRP Topology Table for AS(100)/ID()Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P /32, 1 successors, FD is 2809856 via (2809856/2297856), Serial1/0 via (56960000/2297856), Serial1/1走S1/1方向的值又变大了。用上面的公式可得又是在沿路由路径到目地的出站接口。R3路由表还是不变。总结：无语！ 以后看东西要看完。看仔细点才行。EIGRP-2简单配置&metric计算&default路由(2008-06-10 16:15:07) 转载标签： r&s1/ 简单配置eigrp 使全网互连.2/生成R4 的缺省路由3/看一下eigrp的三张表4/metric计算R1interface Serial1/0ip address serial restart-delay 0clock rate 64000!interface Serial1/1ip address serial restart-delay 0clock rate 64000!interface Serial1/2ip address serial restart-delay 0clock rate 64000router eigrp 90network 55network 55network 55auto-summary!R2interface Serial1/0ip address serial restart-delay 0clock rate 64000!interface Serial1/2ip address serial restart-delay 0clock rate 64000router eigrp 90network 55network 55no auto-summaryR5interface Serial1/0ip address serial restart-delay 0clock rate 64000!interface Serial1/1ip address serial restart-delay 0clock rate 64000router eigrp 90network 55network 55auto-summary!R4interface Loopback0ip address 4 55!interface Loopback1ip address !interface Serial1/1ip address serial restart-delay 0router eigrp 90network 55network no auto-summary!ip default-network 通过此命令生成一条缺省的路由发布给另外那三个路由器此处必须是在router eigrp 里面公告的路由 而且注意汇总 !现在看一下R1的三个表R1#sh ip eigrp neighbors detailIP-EIGRP neighbors for process 90H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num2 Se1/0 14 00:06:35 349 2094 0 3 Version 12.4/1.2, Retrans: 1, Retries: 0, Prefixes: 11 Se1/2 10 00:06:53 51 306 0 9 Version 12.2/1.2, Retrans: 1, Retries: 0, Prefixes: 20 Se1/1 14 00:07:25 96 576 0 17 Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 2R1#sh ip eigrp top detail-linksIP-EIGRP Topology Table for AS(90)/ID()Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia StatusP /8, 1 successors, FD is 2169856, serno 12 via Summary (2169856/0), Null0 via (3705856/3193856), Serial1/1P /24, 1 successors, FD is 2169856, serno 7 via Connected, Serial1/1 via (3193856/2681856), Serial1/2P /8, 1 successors, FD is 2169856, serno 16 via Summary (2169856/0), Null0P /24, 1 successors, FD is 2169856, serno 15 via Connected, Serial1/0P /8, 1 successors, FD is 2169856, serno 13 via Summary (2169856/0), Null0P /24, 1 successors, FD is 2169856, serno 11 via Connected, Serial1/2P /8, 1 successors, FD is 2681856, serno 14 via (2681856/2169856), Serial1/2P /24, 1 successors, FD is 2681856, serno 10 via (2681856/2169856), Serial1/1Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia StatusP /24, 1 successors, FD is 2297856, serno 17 via (2297856/128256), Serial1/0R1#sh ip route eigr /8 is variably subnetted, 2 subnets, 2 masksD /24 90/2681856 via , 00:23:40, Serial1/1D /8 90/2681856 via , 00:23:35, Serial1/2 /8 is variably subnetted, 2 subnets, 2 masksD /8 is a summary, 00:23:35, Null0D* /24 90/2297856 via , 00:23:19, Serial1/0 /8 is variably subnetted, 2 subnets, 2 masksD /8 is a summary, 00:23:20, Null0 /8 is variably subnetted, 2 subnets, 2 masksD /8 is a summary, 00:23:40, Null0METRIC 的计算 下面用一个简单的来计算一下Step1:确定路由的入口:(也就是访问该目标网络的数据包的出口)Step2:收集各个路由的入口的BW/DL信息:R2#show interfaces serial 1 BW 1544 Kbit DLY 20000 (这两个参数是用来控制三层协议的选路,而clock rate是反应链路上真实的速度,这两个参数可以在接口上更改,但仅仅是影响路由协议的选路)Step3:Metric=(10,000,000/BW)+(DL/10)*256BW:单位是:Kbps,多个路由入口中的带宽最小值.DL:单位是:us(微秒),多个路由入口的延迟之和.R1#sh int s1/1Serial1/1 is up, line protocol is up Hardware is M4T Internet address is /24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,R1#sh ip route eigr /8 is variably subnetted, 2 subnets, 2 masksD /24 90/2681856 via , 00:23:40, Serial1/110000000/1544=6476DELAY= (20000+20000)/10=4000256*(6476+4000)=2681856正确!现在修改一下:R1(config)#int s1/1R1(config-if)#bandwidth 1200R1(config-if)#delay 5000R1(config-if)#exitR1(config)#do sh ip route eigrp /8 is variably subnetted, 2 subnets, 2 masksD /24 90/3925248 via , 00:00:14, Serial1/1R1#sh int s1/1Serial1/1 is up, line protocol is up Hardware is M4T Internet address is /24 MTU 1500 bytes, BW 1200 Kbit, DLY 50000 usec,10000000/1200=8333delay=(50000+20000)/10=7000metric=(8333+7000)*256=3925248正确!EIGRP基本实验与度量计算 日期：2010-1-31浏览次数： 994出处：IT傻博士R1:RouterenRouter#conf tEnter configuration commands, one per line. End with CNTL/Z.Router(config)#line con 0Router(config-line)#logg syRouter(config-line)#exec-t 0 0Router(config-line)#exiRouter(config)#no ip domain-loRouter(config)#host R1R1(config)#int s 1R1(config-if)#ip add R1(config-if)#no shutdownR1(config-if)#clo ra 64000R1(config-if)#exiR1(config)#*Mar 1 00:23:29.347: %LINK-3-UPDOWN: Interface Serial1, changed state to upR1(config)#*Mar 1 00:23:30.351: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to upR1(config)#R2:R2#enR2#conf tEnter configuration commands, one per line. End with CNTL/Z.R2(config)#int s 1R2(config-if)#ip add R2(config-if)#no shutdownR2(config-if)#int s 0R2(config-if)#ip add R2(config-if)#no shutdownR2(config-if)#clo ra 64000R2(config-if)#exiR2(config)#R3:R3enR3#conf tEnter configuration commands, one per line. End with CNTL/Z.R3(config)#int s 1R3(config-if)#ip add R3(config-if)#no shutdownR3(config-if)#exi R3(config)#以上的配置已经可以完成由R2分别与R1和R3的通信，测试结果如下：R2#ping Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:!Success rate is 100 percent (5/5), round-trip min/avg/max = 32/34/36 msR2#ping Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:!Success rate is 100 percent (5/5), round-trip min/avg/max = 32/34/36 msR2#回R1启动EIGRP协议。R1(config)#router eigrp ? Autonomous system number 实则为EIGRP的进程号，也可被用来用自治系统号进行分配。R1(config)#router eigrp 1R1(config-router)#net ？ 宣告网络 A.B.C.D EIGRP wild card bits EIGRP支持VLSM，可以在这里输入通配符掩码进行精确匹配。 直接确定R2、R3同时都需要运行EIGRP使R1可以与R3相互交换信息，R2、R3的配置如下：R2:R2#conf tEnter configuration commands, one per line. End with CNTL/Z.R2(config)#router eigrp 1R2(config-router)#net *Mar 1 01:10:21.591: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor (Serial1) is up: new adjacency 与邻居建立邻接关系成功，如何建立的细节请参阅IT傻博士课程。R2(config-router)#net R2(config-router)#exiR2(config)#*Mar 1 01:10:37.699: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor (Serial0) is up: new adjacency 与邻居建立邻接关系。R2(config)#R3:R3(config)#R3(config)#router eigrp 1R3(config-router)#net R3(config-router)#exiR3(config)#*Mar 1 01:09:13.887: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor (Serial1) is up: new adjacency 与邻居建立邻接关系。R3(config)#我们接着在R3上查看路由表可以看见到达R1的路由已经出现，如下。R3#show ip routeCodes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static routeGateway of last resort is not set /24 is subnetted, 1 subnetsC is directly connected, Serial1D /8 90/2681856 via , 00:39:05, Serial1R3#首先我们来分解看一下本条通过EIGRP学习到的路由条目。D /8 90/2681856 via , 00:39:05, Serial1 D: 代表EIGRP。/8: 为我们宣告的网络，在此的形式为主类，因为EIGRP在通过边界路由的时候将进行自动汇总。90/2681856: 括号内的90表明EIGRP的管理距离为90，2681856为到达/8这条链路的开销值。via : 下一跳邻居接口。01:07:51： 时间标记。Serial1： 本地接口。在90/2681856一项内管理距离的值各协议不同，并且随厂家的不同也有不同，定义管理距离值除了各企业以外IETF工程小组也有相关定义。2681856为到达目的地的Metric值（度量）其计算公式如下：BW igrp metric = 10000000/带宽（kbit/s）DLY igrp metric = 延迟总和（微秒microseconds）/10BW eigrp metric = 10000000/带宽（kbit/s）* 256DLY eigrp metric = 延迟总和（微秒microseconds）/10 * 256通过show ip route 可查看相关路由的详细参数。R3#show ip route Routing entry for /8 Known via eigrp 1, distance 90, metric 2681856, type internal Redistributing via eigrp 1 Last update from on Serial1, 01:17:54 ago Routing Descrptor Blocks: * , from , 01:17:54 ago, via Serial1 Route metric is 2681856, traffic share count is 1 Total delay is 40000 microseconds, minimum bandwidth is 1544 Kbit Reliability 255/255, minimum MTU 1500 bytes Loading 1/255, Hops 1R3#从以上R3#show ip route 命令输入的相关信息可以看到到达目的地的延迟总和为4000微秒，而Eigrp的带宽用整个链路的最小带宽为1544Kbit/s，经过计算，算出来的metric的值为2681856，而直接套用如上公式进行计算，计算的结果有一定的偏差，实际的链路带宽应为1544163063619518221124Kb通过此值进行运算即可得到metric为2681856。图示如下：接下来我们看一下Eigrp的Topology Table(称数据库表或拓扑表)R3#show ip eigrp topoIP-EIGRP Topology Table for AS(1)/ID()Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P /8, 1 successors, FD is 2681856 via (2681856/2169856), Serial1P /24, 1 successors, FD is 2169856 via Connected, Serial1R3#从上面摘取的条目可以看出P /8, 1 successors, FD is 2681856 其FD（可行距离）的值为2681856，可行距离即为从源到达目的的最小Metirc值，通过Metric的公式即可计算出，但是第二条P /24, 1 successors, FD is 2169856本条的FD为2169856，差别即在于的网段与R3直接相连到达本路径的最小带宽为1544Kb，延迟总和为20000微秒，通过计算即可得。带宽和延迟是Eigrp进行度量运算的默认参数，除此以外负载和可靠性也可以与带宽和延迟共同参与度量的运算，但是需要人为手动开启此选项，另外MTU(最大传输单元)并不参与Metric的运算，但是Eigrp和Igrp也会跟踪每条路由上最小MTU的大小。通过以下方式可以查看每接口的相关参数R3#show interface s 1Serial1 is up, line protocol is up Hardware is HD64570 Internet address is /24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, 用于Metric运算的相关参数。 reliability 255/255, txload 1/255, rxload 1/255 Encapsulation HDLC, loopback not set Keepalive set (10 sec) Last input 00:00:02, output 00:00:02, output hang never Last clearing of show interface counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 1158 kilobits/sec 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 916 packets input, 59374 bytes, 0 no buffer Received 319 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 922 packets output, 60362 bytes, 0 underruns 0 output errors, 0 collisions, 4 interface resets 0 output buffer failures, 0 output buffers swapped out 1 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=upR3#另外以上BW（带宽）值并非本链路的传输速度为1544Kbit/s，而仅用来作为串口默认的度量值，不会动态改变，即便你的实际传输