CCNP路由實驗之八路由重發(fā)布-創(chuàng)新互聯(lián)
CCNP路由實驗之八 路由重發(fā)布
在前面幾個實驗，已經(jīng)學習了靜態(tài)路由和動態(tài)路由。現(xiàn)在，我們要掌握如何使它們在一個網(wǎng)絡中融合，即路由重發(fā)布。路由重分布可以實現(xiàn)多種路由協(xié)議之間共享路由信息并進行路由信息交換，使得同一個互聯(lián)網(wǎng)絡中高效地支持多種路由協(xié)議提供了可能。執(zhí)行路由重分布的路由器被稱為邊界路由器。因為他們位于兩個或多個自治系統(tǒng)的邊界上。
路由重分布時，計量單位和管理距離是必須要考慮的因素。每一種路由協(xié)議都有自己的度量標準，所以在進行重分布時必須轉(zhuǎn)換度量標準，使得它們兼容。種子度量值（Seed Metric）是定義在路由重分布里的，它是一條從外部重分布進來的路由的初始度量值。路由協(xié)議默認的管理距離如下表：
路由來源 | 管理距離（AD） |
直連口 | 0 |
使用出站口作為靜態(tài)路由 | 0 |
使用下一跳地址作為靜態(tài)路由 | 1 |
EIGRP匯總路由 | 5 |
EBGP（外部） | 20 |
內(nèi)部EIGRP | 90 |
IGRP | 100 |
OSPF | 110 |
IS-IS自治系統(tǒng) | 115 |
RIP | 120 |
EGP外部網(wǎng)關協(xié)議(淘汰) | 140 |
ODR | 160 |
外部EIGRP | 170(重發(fā)布) |
iBGP（內(nèi)部） | 200 |
默認路由 | 默認路由是在路由器找不到具體路由時的一種處理方式，它總是被最后使用 |
未知 | 255 |
注：
管理距離是指一種路由協(xié)議的路由可信度，在正常情況下，管理距離越小，它的優(yōu)先級就越高，也就是可信度越高！路由器根據(jù)管理距離決定哪一個協(xié)議的路由進入路由表
使用出站接口配置的靜態(tài)路由AD實際處于0-1之間
如果AD相同，則會比較路由協(xié)議的度量值（如跳計數(shù)或鏈路的寬帶值），帶有較低度量值的路由會被放置在路由表中；
距離矢量路由協(xié)議（如RIP和IGRP）的度量值為跳數(shù)
EIGRP的度量值默認為帶寬和延遲，其它可選因素是負載，可靠性和大傳輸單元
OSPF的度量值為開銷，默認為10*7/帶寬（單位是bit/s）
如果AD和度量值都相同，那么路由選擇協(xié)議會使用負載均衡，即發(fā)送的數(shù)據(jù)包會平均分配到每個鏈路上。
所有協(xié)議都可以實現(xiàn)負載均衡，EIGRP和IGRP默認時可以支持最多到4條鏈路的不等代價負載均衡，可以通過maximum-paths 命令可以使數(shù)值達到6
AD為255的路由不會被使用
路由重分布并不是完美的，它有如下幾點不足：
路由回環(huán)：根據(jù)重分布的使用方法，路由器有可能將它從一個AS收到的路由信息發(fā)回到這個AS中，這種回饋與距離矢量路由協(xié)議的水平分割問題類似。
路由信息不兼容：不同的路由協(xié)議使用不有的量度值，因為這些量度值可能無法正確引入到不同的路由協(xié)議，使用重分布的路由信息來進行路徑選擇可能不是最優(yōu)的。
收斂時間不一致：不同的路由協(xié)議收斂效率不同，例如，RIP比EIGRP收斂慢，因此如果一條鏈路DOWN掉，EIGRP網(wǎng)絡將比RIP網(wǎng)絡更早得知這一信息。
在配置路由重分布時應注意以下情況：
不要重疊使用路由協(xié)議:不要在同一個網(wǎng)絡里使用兩個不同的路由協(xié)議，在使用不同路由協(xié)議的網(wǎng)絡之間應該有明顯的邊界。
重分布原則：路由必須位于路由選擇表中才能被重分發(fā)
在單邊界的情況下使用雙向重分布: 當一個網(wǎng)絡中只有一個邊界路由器時，雙向重分布工作很穩(wěn)定。如果沒有任何機制來防止路由回環(huán)，不要在一個多邊界的網(wǎng)絡中使用雙向重分布。綜合使用默認路由、路由過濾以及修改管理距離可以防止路由回環(huán)。
有多個邊界路由器的情況下使用單向重分布: 如果有多于一臺路由器作為重分布點，使用單向重分布可以避免回環(huán)和收斂問題。在不需要接收外部路由的路由器上使用默認路由。
實驗一、單邊界多向路由重分布
R1配置（邊界路由器）
R1#conf t
R1(config)#int lo0
R1(config-if)#ip add 1.1.1.1255.255.255.0 //直連路由
R1(config-if)#desc Directly
R1(config-if)#exit
R1(config)#int f1/0
R1(config-if)#desc static
R1(config-if)#ip add 172.168.1.1 255.255.255.0
R1(config-if)#no sh
R1(config-if)#exit
R1(config)#int s2/0
R1(config-if)#desc Internet
R1(config-if)#clock rate 64000
R1(config-if)#ip add 202.100.100.1255.255.255.0
R1(config-if)#no sh
R1(config-if)#exit
R1(config)#int e0/0
R1(config-if)#desc RIP
R1(config-if)#ip add 192.168.12.1255.255.255.0
R1(config-if)#no sh
R1(config-if)#exit
R1(config)#int e0/1
R1(config-if)# desc EIGRP
R1(config-if)#ip add 192.168.13.1255.255.255.0
R1(config-if)#no sh
R1(config-if)#exit
R1(config)#int e0/2
R1(config-if)#desc OSPF
R1(config-if)#ip add 192.168.14.1255.255.255.0
R1(config-if)#no sh
R1(config-if)#exit
R1(config)#int e0/3
R1(config-if)#desc IS-IS
R1(config-if)#ip add 192.168.15.1255.255.255.0
R1(config-if)#ip router isis //將接口宣告到IS-IS路由進程中
R1(config-if)#no sh
R1(config-if)#exit
R1(config)#ip route 0.0.0.0 0.0.0.0202.100.100.2 //默認路由
R1(config)#ip route 172.168.100.0255.255.255.0 172.168.1.2 //靜態(tài)路由
R1(config)#router rip //開啟RIP路由協(xié)議
R1(config-router)#version 2
R1(config-router)#no auto-summary
R1(config-router)#net 192.168.12.0
R1(config-router)#exit
R1(config)#router eigrp 1 //開啟EIGRP路由協(xié)議
R1(config-router)#no auto-summary
R1(config-router)#network 192.168.13.0255.255.255.0
R1(config-router)#exit
R1(config)#router ospf 1 //開啟ospf路由協(xié)議
R1(config-router)#network 192.168.14.0255.255.255.0 area 0
R1(config-router)#exit
R1(config)#router isis //開啟IS-IS路由協(xié)議
R1(config-router)#net49.0001.1111.1111.1111.00
R1(config-router)#exit
R2配置（RIP路由協(xié)議）
R2#conf t
R2(config)#int lo 0
R2(config-if)#ip add 2.2.2.2 255.255.255.0
R2(config-if)#desc RIP
R2(config-if)#exit
R2(config)#int e0/0
R2(config-if)#ip add 192.168.12.2255.255.255.0
R2(config-if)#desc RIP
R2(config-if)#exit
R2(config)#int e0/0
R2(config-if)#no sh
R2(config-if)#exit
R2(config)#router rip
R2(config-router)#ver 2
R2(config-router)#no auto-summary
R2(config-router)#net 2.2.2.0
R2(config-router)#net 192.168.12.0
R2(config-router)#exit
R3配置：（EIGRP路由協(xié)議）
R3#conf t
R3(config)#int lo0
R3(config-if)#ip add 3.3.3.3255.255.255.0
R3(config-if)#desc EIGRP
R3(config-if)#exit
R3(config)#int e0/0
R3(config-if)#desc EIGRP
R3(config-if)#ip add 192.168.13.2255.255.255.0
R3(config-if)#no sh
R3(config-if)#exit
R3(config)#router eigrp 1
R3(config-router)#net 192.168.13.0
R3(config-router)#net 3.3.3.0
R3(config-router)#exit
R4配置：（OSPF路由協(xié)議）
R4#conf t
R4(config)#int lo0
R4(config-if)#desc OSPF
R4(config-if)#ip add 4.4.4.4255.255.255.0
R4(config-if)#exit
R4(config)#int e0/0
R4(config-if)#desc OSPF
R4(config-if)#ip add 192.168.14.2255.255.255.0
R4(config-if)#no sh
R4(config-if)#exit
R4(config)#router ospf 1
R4(config-router)#net 4.4.4.0255.255.255.0 area 0
R4(config-router)#net 192.168.14.0255.255.255.0 area 0
R4(config-router)#exit
R5配置：（IS-IS路由協(xié)議）
R5#conf t
R5(config)#int lo0
R5(config-if)#desc IS-IS
R5(config-if)#ip add 5.5.5.5255.255.255.0
R5(config-if)#ip router isis
R5(config-if)#exit
R5(config)#int e0/0
R5(config-if)#desc IS-IS
R5(config-if)#ip add 192.168.15.2255.255.255.0
R5(config-if)#ip router isis
R5(config-if)#no sh
R5(config-if)#exit
R5(config)#router isis
R5(config-router)#net49.0001.5555.5555.5555.00
R5(config-router)#exit
Branch配置（靜態(tài)路由）
Branch#conf t
Branch(config)#int lo0
Branch(config-if)#ip add 172.168.100.1255.255.255.0
Branch(config-if)#exit
Branch(config)#int fa0/0
Branch(config-if)#ip add 172.168.1.2255.255.255.0
Branch(config-if)#no sh
Branch(config-if)#exit
Branch(config)#ip route 0.0.0.0 0.0.0.0172.168.1.1 //回程路由
Internet配置：
Internet#conf t
Internet(config)#int lo0
Internet(config-if)#ip add 10.10.10.10255.255.255.0
Internet(config-if)#exit
Internet(config)#int s0/0
Internet(config-if)#clock rate 64000
Internet(config-if)#ip add 202.100.100.2255.255.255.0
Internet(config-if)#no sh
Internet(config-if)#exit
Internet(config)#ip route 0.0.0.0 0.0.0.0202.100.100.1 //回程路由
完成以上基本配置后R1上運行多種路由協(xié)議，它可以與所有網(wǎng)絡互通，是網(wǎng)絡上的邊界路由。此時在它之上使用路由重分布功能，就可以實現(xiàn)各路由協(xié)議交換路由信息。下面開始
第一向R2的RIP協(xié)議注入靜態(tài)路由、默認路由、直連路由、EIGRP、OSPF、ISIS,在向RIP區(qū)域重分布路由的時候，必須指定度量值，否則由于注入的路由度量值會變成無窮大而無法加入路由表，因此必須手工指定metric值，注意RIP的metric不能大于15，因為RIP大跳數(shù)為16，可以通過"default-metric"設置默認種子度量值，只有重分布靜態(tài)路由或默認路由可以不指定種子度量值。
R1#conf t
R1(config)#router rip
R1(config-router)#default-informationoriginate //注入默認路由
R1(config-router)#redistribute static//注入靜態(tài)路由
R1(config-router)#redistribute connectedmetric 6 //注入直連路由
R1(config-router)#redistribute eigrp 1 metric 3//注入EIGRP路由
R1(config-router)#redistribute ospf 1 metric 4//注入OSPF路由
R1(config-router)#redistribute isis level-1-2 metric 5//注入ISIS路由
R2#sh ip rou //此時R2路由表變化。注意路由代碼為"R"的metric值；
Codes: 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 route、
Gateway of last resort is 192.168.12.1to network 0.0.0.0
C 192.168.12.0/24 is directly connected, Ethernet0/0
1.0.0.0/24 is subnetted, 1 subnets
R 1.1.1.0 [120/6] via 192.168.12.1, 00:00:01, Ethernet0/0
R 192.168.13.0/24 [120/6] via 192.168.12.1, 00:00:01, Ethernet0/0
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback0
R 192.168.14.0/24 [120/6] via 192.168.12.1, 00:00:01, Ethernet0/0
R 3.0.0.0/8 [120/3] via 192.168.12.1, 00:00:01, Ethernet0/0
R 192.168.15.0/24 [120/6] via 192.168.12.1, 00:00:02, Ethernet0/0
4.0.0.0/32 is subnetted, 1 subnets
R 4.4.4.4 [120/4] via 192.168.12.1, 00:00:02, Ethernet0/0
R 202.100.100.0/24 [120/6] via 192.168.12.1, 00:00:02, Ethernet0/0
5.0.0.0/24 is subnetted, 1 subnets
R 5.5.5.0 [120/5] via 192.168.12.1, 00:00:03, Ethernet0/0
172.168.0.0/24 is subnetted, 2 subnets
R 172.168.1.0 [120/6] via 192.168.12.1, 00:00:03, Ethernet0/0
R 172.168.100.0 [120/1] via 192.168.12.1, 00:00:03, Ethernet0/0
R* 0.0.0.0/0 [120/1] via 192.168.12.1, 00:00:03, Ethernet0/0
第二向R3的EIGRP路由協(xié)議注入靜態(tài)路由、默認路由、直連路由、RIP、OSPF、ISIS，由于重分布到EIGRP的路由管理距離會變成無限大，所以必須手工分別設置帶寬、延遲、可靠性、負載以及MTU的參數(shù)值。在"Redistribute"命令中用參數(shù)"metric"指定的種子度量值優(yōu)先于在路由模式下使用"default-metric命令設定的默認的種子度量值".注意靜態(tài)、默認、直連不需要指定metric值
R1#conf t
R1(config)#router eigrp1
R1(config-router)#redistribute static //注入靜態(tài)和默認路由,或使用network0.0.0.0
R1(config-router)#redistributeconnected//注入直連路由
R1(config-router)#redistribute ripmetric 1000 100 255 1 1500 //注入rip路由
R1(config-router)#redistribute ospf 1metric 1000 100 255 1 1500//注入OSPF路由
R1(config-router)#redistribute isislevel-1-2 metric 1000 100 255 1 1500//注入ISIS路由
R3#sh ip rou //R3路由表，重分布的路由代碼為"D EX"
Codes: 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 route
Gateway of last resort is 192.168.13.1to network 0.0.0.0
D EX 192.168.12.0/24 [170/307200] via192.168.13.1, 00:00:04, Ethernet0/0
1.0.0.0/24 is subnetted, 1 subnets
D EX 1.1.1.0 [170/409600] via 192.168.13.1, 00:00:04, Ethernet0/0
C 192.168.13.0/24 is directly connected, Ethernet0/0
2.0.0.0/24 is subnetted, 1 subnets
D EX 2.2.2.0 [170/2611200] via 192.168.13.1, 00:11:03, Ethernet0/0
D EX 192.168.14.0/24 [170/307200] via192.168.13.1, 00:00:04, Ethernet0/0
3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 3.3.3.0/24 is directly connected, Loopback0
D 3.0.0.0/8 is a summary, 01:24:53, Null0
D EX 192.168.15.0/24 [170/307200] via 192.168.13.1,00:00:05, Ethernet0/0
4.0.0.0/32 is subnetted, 1 subnets
D EX 4.4.4.4 [170/2611200] via 192.168.13.1, 00:09:40, Ethernet0/0
D EX 202.100.100.0/24 [170/2195456] via192.168.13.1, 00:00:20, Ethernet0/0
5.0.0.0/24 is subnetted, 1 subnets
D EX 5.5.5.0 [170/2611200] via 192.168.13.1, 00:09:15, Ethernet0/0
172.168.0.0/24 is subnetted, 2 subnets
D EX 172.168.1.0 [170/284160] via 192.168.13.1, 00:00:20, Ethernet0/0
D EX 172.168.100.0 [170/284160] via 192.168.13.1, 00:20:35, Ethernet0/0
D*EX 0.0.0.0/0 [170/2195456] via192.168.13.1, 00:20:35, Ethernet0/0
第三向R4的OSPF路由協(xié)議注入靜態(tài)路由、默認路由、直連路由、RIP、EIGRP、ISIS，重發(fā)布時管理距離為110且Metric為20，當然可也以通過"metric-type"設置類型，或者"metric"參數(shù)設置外部路徑成本。注意在向ospf重發(fā)布是需要加上subnets，否則只重發(fā)布主類網(wǎng)
R1#conf t
R1(config)#router ospf 1
R1(config-router)#default-informationoriginate //注入默認路由
R1(config-router)#redistribute connectedsubnets//注入直連路由
R1(config-router)#redistribute staticsubnets//注入靜態(tài)路由
R1(config-router)#redistribute ripsubnets//注入RIP路由
R1(config-router)#redistribute eigrp 1subnets//注入EIGRP路由
R1(config-router)#redistribute isislevel-1-2 subnets//注入ISIS路由
R4#ship rou//重分布進OSPF的路由被路由器R4學到，代碼為"O E2"，
Codes: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 route
Gateway of last resort is 192.168.14.1to network 0.0.0.0
O E2 192.168.12.0/24 [110/20] via192.168.14.1, 00:11:00, Ethernet0/0
1.0.0.0/24 is subnetted, 1 subnets
O E2 1.1.1.0 [110/20] via 192.168.14.1, 00:10:50, Ethernet0/0
O E2 192.168.13.0/24 [110/20] via192.168.14.1, 00:11:00, Ethernet0/0
2.0.0.0/24 is subnetted, 1 subnets
O E2 2.2.2.0 [110/20] via 192.168.14.1, 00:09:33, Ethernet0/0
C 192.168.14.0/24 is directly connected, Ethernet0/0
O E2 3.0.0.0/8 [110/20] via192.168.14.1, 00:08:47, Ethernet0/0
O E2 192.168.15.0/24 [110/20] via192.168.14.1, 00:11:01, Ethernet0/0
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, Loopback0
O E2 202.100.100.0/24 [110/20] via192.168.14.1, 00:11:01, Ethernet0/0
5.0.0.0/24 is subnetted, 1 subnets
O E2 5.5.5.0 [110/20] via 192.168.14.1, 00:08:10, Ethernet0/0
172.168.0.0/24 is subnetted, 2 subnets
O E2 172.168.1.0 [110/20] via 192.168.14.1, 00:10:53, Ethernet0/0
O E2 172.168.100.0 [110/20] via 192.168.14.1, 00:10:18, Ethernet0/0
O*E2 0.0.0.0/0 [110/1] via 192.168.14.1,00:11:58, Ethernet0/0
第四向R5的ISIS路由協(xié)議注入靜態(tài)路由、默認路由、直連路由、RIP、EIGRP、ISIS，重發(fā)布時管理距離為115且Metric為10。當把其他路由協(xié)議重分發(fā)到isis中時，必須使用level-2類型.默認就是Level-2
R1#conf t
R1(config)#router isis
R1(config-router)#default-informationoriginate //注入默認路由
R1(config-router)#redistribute static//注入靜態(tài)路由
R1(config-router)#redistribute connected//注入直連路由
R1(config-router)#redistribute rip//注入RIP路由
R1(config-router)#redistribute ospf 1//注入OSPF路由
R1(config-router)#redistribute eigrp 1//注入EIGRP路由
R5#sh ip rou //R5的路由表
Codes: 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 route
Gateway of last resort is 192.168.15.1to network 0.0.0.0
i L2 192.168.12.0/24 [115/10] via192.168.15.1, Ethernet0/0
1.0.0.0/24 is subnetted, 1 subnets
i L2 1.1.1.0 [115/10] via 192.168.15.1, Ethernet0/0
i L2 192.168.13.0/24 [115/10] via192.168.15.1, Ethernet0/0
2.0.0.0/24 is subnetted, 1 subnets
i L2 2.2.2.0 [115/10] via 192.168.15.1, Ethernet0/0
i L2 192.168.14.0/24 [115/10] via192.168.15.1, Ethernet0/0
i L2 3.0.0.0/8 [115/10] via192.168.15.1, Ethernet0/0
C 192.168.15.0/24 is directly connected, Ethernet0/0
4.0.0.0/32 is subnetted, 1 subnets
i L2 4.4.4.4 [115/10] via 192.168.15.1, Ethernet0/0
i L2 202.100.100.0/24 [115/10] via192.168.15.1, Ethernet0/0
5.0.0.0/24 is subnetted, 1 subnets
C 5.5.5.0 is directly connected, Loopback0
172.168.0.0/24 is subnetted, 2 subnets
i L2 172.168.1.0 [115/10] via 192.168.15.1, Ethernet0/0
i L2 172.168.100.0 [115/10] via 192.168.15.1,Ethernet0/0
i*L2 0.0.0.0/0 [115/10] via192.168.15.1, Ethernet0/0
實驗二、多點多向路由重發(fā)布
R2配置：（邊界路由）
R2#conft
R2(config)#inte0/0
R2(config-if)#ipadd 192.168.21.2 255.255.255.0
R2(config-if)#nosh
R2(config-if)#exit
R2(config)#inte0/1
R2(config-if)#ipadd 192.168.24.2 255.255.255.0
R2(config-if)#nosh
R2(config-if)#exit
R2(config)#inte0/2
R2(config-if)#ipadd 192.168.25.2 255.255.255.0
R2(config-if)#nosh
R2(config-if)#exit
R2(config)#inte0/3
R2(config-if)#ipadd 192.168.26.2 255.255.255.0
R2(config-if)#iprouter isis
R2(config-if)#nosh
R2(config-if)#exit
R2(config)#routerrip
R2(config-router)#ver2
R2(config-router)#noau
R2(config-router)#net192.168.21.0
R2(config-router)#exit
R2(config)#routereigrp 1
R2(config-router)#net192.168.24.0
R2(config-router)#exit
R2(config)#routerospf 1
R2(config-router)#net192.168.25.0 255.255.255.0 area 0
R2(config-router)#exit
R2(config)#routerisis
R2(config-router)#net49.0001.2222.2222.2222.00
R2(config-router)#exit
R3配置（邊界路由器）
R3#conft
R3(config)#inte0/0
R3(config-if)#ipadd 192.168.31.3 255.255.255.0
R3(config-if)#nosh
R3(config-if)#exit
R3(config)#inte0/1
R3(config-if)#ipadd 192.168.34.3 255.255.255.0
R3(config-if)#nosh
R3(config-if)#exit
R3(config)#inte0/2
R3(config-if)#ipadd 192.168.35.3 255.255.255.0
R3(config-if)#nosh
R3(config-if)#exit
R3(config)#inte0/3
R3(config-if)#ipadd 192.168.36.3 255.255.255.0
R3(config-if)#iprouter isis
R3(config-if)#nosh
R3(config-if)#exit
R3(config)#routerrip
R3(config-router)#ver2
R3(config-router)#noau
R3(config-router)#net192.168.31.0
R3(config-router)#exit
R3(config)#routereigrp 1
R3(config-router)#net192.168.34.0
R3(config-router)#exit
R3(config)#routerospf 1
R3(config-router)#net192.168.35.0 255.255.255.0 area 0
R3(config-router)#exit
R3(config)#routerisis
R3(config-router)#net49.0001.3333.3333.3333.00
R3(config-router)#exit
R1配置（rip路由協(xié)議）
R1#conft
R1(config)#inte0/0
R1(config-if)#ipadd 192.168.21.1 255.255.255.0
R1(config-if)#nosh
R1(config-if)#exit
R1(config)#inte0/1
R1(config-if)#ipadd 192.168.31.1 255.255.255.0
R1(config-if)#nosh
R1(config-if)#exit
R1(config-if)#ipadd 1.1.1.1 255.255.255.0
R1(config-if)#exit
R1(config)#routerrip
R1(config-router)#ver2
R1(config-router)#noau
R1(config-router)#net192.168.21.0
R1(config-router)#noau
R1(config-router)#net192.168.31.0
R1(config-router)#net1.1.1.0
R4配置（eigrp路由）
R4#conft
R4(config)#inte0/0
R4(config-if)#ipadd 192.168.24.4 255.255.255.0
R4(config-if)#nosh
R4(config-if)#exit
R4(config)#inte0/1
R4(config-if)#ipadd 192.168.34.4 255.255.255.0
R4(config-if)#nosh
R4(config-if)#exit
R4(config)#routereigrp 1
R4(config-router)#net192.168.34.0
R4(config-router)#net192.168.24.0
第一向R1的RIP路由協(xié)議注入EIGRP、OSPF、ISIS
R2#conft
R2(config)#routerrip
R2(config-router)#default-metric4
R2(config-router)#redistributeeigrp 1
R2(config-router)#redistributeospf 1
R2(config-router)#redistributeisis level-1-2
R3#conft
R3(config)#routerrip
R3(config-router)#default-metric4
R3(config-router)#redistributeeigrp 1
R3(config-router)#redistributeospf 1
R3(config-router)#redistributeisis level-1-2
第二向R4的EIGRP路由協(xié)議注入RIP、OSPF、ISIS
R2#conft
R2(config)#routereigrp 1
R2(config-router)#default-metric1000 2500 255 1 1500
R2(config-router)#redistributerip
R2(config-router)#redistributeospf 1
R2(config-router)#redistributeisis level-1-2
R3#conft
R3(config)#routereigrp 1
R3(config-router)#default-metric1000 2500 255 1 1500
R3(config-router)#redistributerip
R3(config-router)#redistributeospf 1
R3(config-router)#redistributeisis level-1-2
第三向R5的OSPF路由協(xié)議中注入RIP、EIGRP、ISIS
R2#conft
R2(config)#routerospf 1
R2(config-router)#redistributerip subnets
R2(config-router)#redistributeeigrp 1 subnets
R2(config-router)#redistributeisis level-1-2 subnets
R3#conft
R3(config)#routerospf 1
R3(config-router)#redistributerip subnets
R3(config-router)#redistributeeigrp 1 subnets
R3(config-router)#redistributeisis level-1-2 subnets
第四向R6的ISIS路由協(xié)議注入RIP、EIGRP、OSPF
R2#conf t
R2(config)#routerisis
R2(config-router)#redistributerip level-2
R2(config-router)#redistributeeigrp 1 level-2
R2(config-router)#redistributeospf 1 level-2
R3#conft
R3(config-router)#redistributerip level-2
R3(config-router)#redistributeeigrp 1 level-2
R3(config-router)#redistributeospf 1 level-2
先查看R2和R3的路由表，留意紅色標記的路由，其實并不是最佳路由，也就是說出現(xiàn)了次優(yōu)路由。
R2#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o- ODR, P - periodic downloaded static route
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
i L2 1.1.1.0 [115/20] via192.168.26.6, Ethernet0/3
O E2 192.168.31.0/24 [110/20] via 192.168.25.5, 00:15:21,Ethernet0/2
C 192.168.25.0/24 is directly connected,Ethernet0/2
D 4.0.0.0/8 [90/409600] via 192.168.24.4,01:46:16, Ethernet0/1
C 192.168.24.0/24 is directly connected,Ethernet0/1
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/11] via 192.168.25.5,00:15:21, Ethernet0/2
6.0.0.0/24 is subnetted, 1 subnets
iL1 6.6.6.0 [115/20] via 192.168.26.6,Ethernet0/3
C 192.168.26.0/24 is directly connected,Ethernet0/3
C 192.168.21.0/24 is directly connected,Ethernet0/0
i L1192.168.36.0/24 [115/20] via 192.168.26.6, Ethernet0/3
D 192.168.34.0/24 [90/307200] via192.168.24.4, 01:46:19, Ethernet0/1
O 192.168.35.0/24 [110/20] via 192.168.25.5,00:15:25, Ethernet0/2
R3#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o - ODR, P - periodic downloaded staticroute
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
O E2 1.1.1.0 [110/20] via192.168.35.5, 00:23:48, Ethernet0/2
C 192.168.31.0/24 is directly connected,Ethernet0/0
O 192.168.25.0/24 [110/20] via 192.168.35.5,00:23:48, Ethernet0/2
D 4.0.0.0/8 [90/409600] via 192.168.34.4,01:54:22, Ethernet0/1
D 192.168.24.0/24 [90/307200] via192.168.34.4, 01:54:22, Ethernet0/1
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/11] via 192.168.35.5,00:23:48, Ethernet0/2
6.0.0.0/24 is subnetted, 1 subnets
O E2 6.6.6.0 [110/20] via 192.168.35.5, 00:23:50, Ethernet0/2
i L1192.168.26.0/24 [115/20] via 192.168.36.6, Ethernet0/3
O E2 192.168.21.0/24 [110/20] via 192.168.35.5, 00:23:50,Ethernet0/2
C 192.168.36.0/24 is directly connected,Ethernet0/3
C 192.168.34.0/24 is directly connected,Ethernet0/1
C 192.168.35.0/24 is directly connected,Ethernet0/2
分析：在單點重分發(fā)下似乎沒有這種情況，這是因為發(fā)往一個方向的路由不會被重分發(fā)回來。但是在多點雙向時情況就不同了，自己分發(fā)出去的路由會被另一個協(xié)議重分發(fā)回來的。如果AD值高的路由協(xié)議向AD值低的路由協(xié)議中重分發(fā)，就會產(chǎn)生次優(yōu)路由，路由環(huán)路等問題，反之，AD值低的路由協(xié)議向AD高的路由協(xié)議重分發(fā)，就不會發(fā)生這個問題。注意錯誤發(fā)生在邊界路由器上。此時就要使用路由策略來解決，方法如下
路由過濾 不讓產(chǎn)生環(huán)路的路由條目進入我這臺路由器，這樣也就不會產(chǎn)生次優(yōu)路徑了
修改管理距離AD 把次優(yōu)路由條目的AD值調(diào)高，高到路由器即便看到兩條路由條目去往同一目的地，也不會把次優(yōu)路由寫入路由表。這種方法比前一種好在如果最佳路徑down了，次優(yōu)路由變成備份路由使用。
這里我們修改管理距離，然后再次查看每個路由器的路由表，注意R1、R4、R5、R6間的負載均衡。
R2#conf t
R2(config)#routerrip
R2(config-router)#distance111 //修改RIP外部路由的管理距離，使小于ISIS、ospf 、Eigrp
R2(config-router)#exit
R2(config)#routerospf 1
R2(config-router)#distanceospf external 170 //修改OSPF的管理距離大于isis 和rip，等于eigrp
R3#conf t
R3(config)#routerrip
R3(config-router)#distance111
R3(config-router)#exit
R3(config)#routerospf 1
R3(config-router)#distanceospf external 170
R2#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o- ODR, P - periodic downloaded static route
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
R 1.1.1.0 [111/1] via 192.168.21.1,00:00:04, Ethernet0/0
R 192.168.31.0/24 [111/1] via 192.168.21.1,00:00:04, Ethernet0/0
C 192.168.25.0/24 is directly connected,Ethernet0/2
D 4.0.0.0/8 [90/409600] via 192.168.24.4,00:00:04, Ethernet0/1
C 192.168.24.0/24 is directly connected,Ethernet0/1
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/11] via 192.168.25.5,00:00:04, Ethernet0/2
6.0.0.0/24 is subnetted, 1 subnets
iL1 6.6.6.0 [115/20] via 192.168.26.6,Ethernet0/3
C 192.168.26.0/24 is directly connected,Ethernet0/3
C 192.168.21.0/24 is directly connected,Ethernet0/0
i L1192.168.36.0/24 [115/20] via 192.168.26.6, Ethernet0/3
D 192.168.34.0/24 [90/307200] via192.168.24.4, 00:00:08, Ethernet0/1
O 192.168.35.0/24 [110/20] via 192.168.25.5,00:00:08, Ethernet0/2
R3#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o - ODR, P - periodic downloaded staticroute
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
R 1.1.1.0 [111/1] via 192.168.31.1,00:00:00, Ethernet0/0
C 192.168.31.0/24 is directly connected,Ethernet0/0
O 192.168.25.0/24 [110/20] via 192.168.35.5,00:00:01, Ethernet0/2
D 4.0.0.0/8 [90/409600] via 192.168.34.4,00:00:01, Ethernet0/1
D 192.168.24.0/24 [90/307200] via192.168.34.4, 00:00:01, Ethernet0/1
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/11] via 192.168.35.5,00:00:01, Ethernet0/2
6.0.0.0/24 is subnetted, 1 subnets
iL1 6.6.6.0 [115/20] via 192.168.36.6,Ethernet0/3
i L1192.168.26.0/24 [115/20] via 192.168.36.6, Ethernet0/3
R 192.168.21.0/24 [111/1] via 192.168.31.1,00:00:02, Ethernet0/0
C 192.168.36.0/24 is directly connected,Ethernet0/3
C 192.168.34.0/24 is directly connected,Ethernet0/1
C 192.168.35.0/24 is directly connected,Ethernet0/2
R1#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o - ODR, P - periodic downloaded staticroute
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
C 192.168.31.0/24 is directly connected,Ethernet0/1
R 192.168.25.0/24 [120/4] via 192.168.31.3,00:00:20, Ethernet0/1
[120/4] via 192.168.21.2,00:00:14, Ethernet0/0
R 4.0.0.0/8 [120/4] via 192.168.31.3,00:00:20, Ethernet0/1
[120/4] via 192.168.21.2,00:00:14, Ethernet0/0
R 192.168.24.0/24 [120/4] via 192.168.31.3,00:00:20, Ethernet0/1
[120/4] via 192.168.21.2,00:00:14, Ethernet0/0
5.0.0.0/32 is subnetted, 1 subnets
R 5.5.5.5 [120/4] via 192.168.31.3,00:00:22, Ethernet0/1
[120/4] via 192.168.21.2,00:00:16, Ethernet0/0
6.0.0.0/24 is subnetted, 1 subnets
R 6.6.6.0 [120/4] via 192.168.31.3,00:00:24, Ethernet0/1
[120/4] via 192.168.21.2,00:00:17, Ethernet0/0
R 192.168.26.0/24 [120/4] via 192.168.31.3,00:00:24, Ethernet0/1
C 192.168.21.0/24 is directly connected,Ethernet0/0
R 192.168.36.0/24 [120/4] via 192.168.21.2,00:00:17, Ethernet0/0
R 192.168.34.0/24 [120/4] via 192.168.31.3,00:00:24, Ethernet0/1
[120/4] via 192.168.21.2,00:00:17, Ethernet0/0
R 192.168.35.0/24 [120/4] via 192.168.31.3,00:00:24, Ethernet0/1
[120/4] via 192.168.21.2,00:00:17, Ethernet0/0
R4#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o - ODR, P - periodic downloaded staticroute
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
DEX 1.1.1.0 [170/3225600] via192.168.34.3, 00:00:07, Ethernet0/1
[170/3225600] via 192.168.24.2,00:00:07, Ethernet0/0
D EX192.168.31.0/24 [170/3225600] via 192.168.34.3, 00:00:07, Ethernet0/1
[170/3225600] via192.168.24.2, 00:00:07, Ethernet0/0
D EX192.168.25.0/24 [170/3225600] via 192.168.34.3, 00:00:07, Ethernet0/1
[170/3225600] via192.168.24.2, 00:00:07, Ethernet0/0
4.0.0.0/8 is variably subnetted, 2subnets, 2 masks
C 4.4.4.0/24 is directly connected, Loopback0
D 4.0.0.0/8 is a summary, 00:00:09, Null0
C 192.168.24.0/24 is directly connected,Ethernet0/0
5.0.0.0/32 is subnetted, 1 subnets
DEX 5.5.5.5 [170/3225600] via192.168.34.3, 00:00:09, Ethernet0/1
[170/3225600] via 192.168.24.2,00:00:09, Ethernet0/0
6.0.0.0/24 is subnetted, 1 subnets
DEX 6.6.6.0 [170/3225600] via192.168.34.3, 00:00:10, Ethernet0/1
[170/3225600] via 192.168.24.2,00:00:10, Ethernet0/0
D EX192.168.26.0/24 [170/3225600] via 192.168.34.3, 00:00:10, Ethernet0/1
D EX192.168.21.0/24 [170/3225600] via 192.168.34.3, 00:00:10, Ethernet0/1
[170/3225600] via192.168.24.2, 00:00:10, Ethernet0/0
D EX192.168.36.0/24 [170/3225600] via 192.168.24.2, 00:00:10, Ethernet0/0
C 192.168.34.0/24 is directly connected,Ethernet0/1
D EX192.168.35.0/24 [170/3225600] via 192.168.34.3, 00:00:10, Ethernet0/1
[170/3225600] via192.168.24.2, 00:00:10, Ethernet0/0
R5# ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o - ODR, P - periodic downloaded staticroute
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
OE2 1.1.1.0 [110/20] via 192.168.35.3,00:00:02, Ethernet0/1
[110/20] via 192.168.25.2,00:00:02, Ethernet0/0
O E2192.168.31.0/24 [110/20] via 192.168.35.3, 00:00:02, Ethernet0/1
[110/20] via 192.168.25.2,00:00:02, Ethernet0/0
C 192.168.25.0/24 is directly connected,Ethernet0/0
O E24.0.0.0/8 [110/20] via 192.168.35.3, 00:00:02, Ethernet0/1
[110/20] via 192.168.25.2,00:00:02, Ethernet0/0
O E2192.168.24.0/24 [110/20] via 192.168.35.3, 00:00:04, Ethernet0/1
[110/20] via 192.168.25.2,00:00:04, Ethernet0/0
5.0.0.0/24 is subnetted, 1 subnets
C 5.5.5.0 is directly connected, Loopback0
6.0.0.0/24 is subnetted, 1 subnets
OE2 6.6.6.0 [110/20] via 192.168.35.3,00:00:06, Ethernet0/1
[110/20] via 192.168.25.2,00:00:06, Ethernet0/0
O E2192.168.26.0/24 [110/20] via 192.168.35.3, 00:00:06, Ethernet0/1
O E2192.168.21.0/24 [110/20] via 192.168.35.3, 00:00:06, Ethernet0/1
[110/20] via 192.168.25.2,00:00:06, Ethernet0/0
O E2192.168.36.0/24 [110/20] via 192.168.25.2, 00:00:06, Ethernet0/0
O E2192.168.34.0/24 [110/20] via 192.168.35.3, 00:00:06, Ethernet0/1
[110/20] via 192.168.25.2,00:00:06, Ethernet0/0
C 192.168.35.0/24 is directly connected,Ethernet0/1
R6#ship rou
Codes: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 - OSPFexternal type 2
i - IS-IS, su - IS-IS summary, L1 -IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidatedefault, U - per-user static route
o - ODR, P - periodic downloaded staticroute
Gatewayof last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
iL2 1.1.1.0 [115/10] via 192.168.36.3,Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
i L2192.168.31.0/24 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
i L2192.168.25.0/24 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
i L24.0.0.0/8 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
i L2192.168.24.0/24 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
5.0.0.0/32 is subnetted, 1 subnets
iL2 5.5.5.5 [115/10] via 192.168.36.3,Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
6.0.0.0/24 is subnetted, 1 subnets
C 6.6.6.0 is directly connected, Loopback0
C 192.168.26.0/24 is directly connected,Ethernet0/0
i L2192.168.21.0/24 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
C 192.168.36.0/24 is directly connected,Ethernet0/1
i L2192.168.34.0/24 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Ethernet0/0
i L2192.168.35.0/24 [115/10] via 192.168.36.3, Ethernet0/1
[115/10] via 192.168.26.2,Eth
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