使用分發列表過濾路由及路由彙總、防環

拓撲圖

說明：IP及接口配置如上所示，左邊運行OSPF，右邊運行EIGRP

實驗目的：掌握用分發列表來過濾路由

在重分佈路由時使用路由彙總來下降路由器的負擔，以及帶來的問題

具體要求：R2過濾掉1.1.1.0的路由，R5在向R4通告的時候過濾掉172.16.55.0的路由。

Ospf向eigrp通告路由時將路由彙總10.0.0.0/8的

Eigrp向Ospf通告路由時將路由彙總成172.16.0.0/16的

環回口路由能夠不用匯總

實驗步驟：

1. 配置IP地址以及路由協議

2. 在R3上配置重分佈

配置命令：

router eigrp 90

redistribute ospf 110 metric 1544 100 255 1 1500

network 33.33.33.0 0.0.0.255

network 172.16.34.0 0.0.0.255

no auto-summary

!

router ospf 110

router-id 3.3.3.3

log-adjacency-changes

redistribute eigrp 90 subnets tag 8888

network 3.3.3.0 0.0.0.255 area 0

network 10.2.2.0 0.0.0.255 area 0

R1#show ip route

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

O 2.2.2.0 [110/65] via 10.1.1.2, 00:21:34, Serial0/0

33.0.0.0/24 is subnetted, 1 subnets

O E2 33.33.33.0 [110/20] via 10.1.1.2, 00:21:34, Serial0/0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/129] via 10.1.1.2, 00:21:34, Serial0/0

4.0.0.0/24 is subnetted, 1 subnets

O E2 4.4.4.0 [110/20] via 10.1.1.2, 00:21:34, Serial0/0

5.0.0.0/24 is subnetted, 1 subnets

O E2 5.5.5.0 [110/20] via 10.1.1.2, 00:21:34, Serial0/0

172.16.0.0/24 is subnetted, 3 subnets

O E2 172.16.55.0 [110/20] via 10.1.1.2, 00:21:37, Serial0/0

O E2 172.16.45.0 [110/20] via 10.1.1.2, 00:21:37, Serial0/0

O E2 172.16.34.0 [110/20] via 10.1.1.2, 00:21:37, Serial0/0

10.0.0.0/24 is subnetted, 2 subnets

O 10.2.2.0 [110/128] via 10.1.1.2, 00:21:37, Serial0/0

C 10.1.1.0 is directly connected, Serial0/0

此時，全部路由器都有全部的路由。

3. 在R2上配置分發列表過濾路由1.1.1.0

R2(config)#ip access-list stan 10

R2(config-std-nacl)#10 deny 1.1.1.0

R2(config-std-nacl)#20 permit any

R2(config)#router ospf 110

R2(config-router)#distribute-list 10 in s0/0

配置結果查看：

R2#show ip route

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

33.0.0.0/24 is subnetted, 1 subnets

O E2 33.33.33.0 [110/20] via 10.2.2.3, 00:00:17, Serial0/1

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/65] via 10.2.2.3, 00:00:17, Serial0/1

4.0.0.0/24 is subnetted, 1 subnets

O E2 4.4.4.0 [110/20] via 10.2.2.3, 00:00:17, Serial0/1

5.0.0.0/24 is subnetted, 1 subnets

O E2 5.5.5.0 [110/20] via 10.2.2.3, 00:00:17, Serial0/1

172.16.0.0/24 is subnetted, 3 subnets

O E2 172.16.55.0 [110/20] via 10.2.2.3, 00:00:17, Serial0/1

O E2 172.16.45.0 [110/20] via 10.2.2.3, 00:00:17, Serial0/1

O E2 172.16.34.0 [110/20] via 10.2.2.3, 00:00:18, Serial0/1

10.0.0.0/24 is subnetted, 2 subnets

C 10.2.2.0 is directly connected, Serial0/1

C 10.1.1.0 is directly connected, Serial0/0

此時R2上面已經沒有1.1.1.0的路由，但R3的路由表中還有此條路由

R3#show ip route

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 not set

1.0.0.0/24 is subnetted, 1 subnets

O 1.1.1.0 [110/129] via 10.2.2.2, 00:29:56, Serial0/1

2.0.0.0/24 is subnetted, 1 subnets

O 2.2.2.0 [110/65] via 10.2.2.2, 00:29:56, Serial0/1

33.0.0.0/24 is subnetted, 1 subnets

C 33.33.33.0 is directly connected, Loopback1

3.0.0.0/24 is subnetted, 1 subnets

C 3.3.3.0 is directly connected, Loopback0

4.0.0.0/24 is subnetted, 1 subnets

D 4.4.4.0 [90/2297856] via 172.16.34.4, 00:31:50, Serial0/2

5.0.0.0/24 is subnetted, 1 subnets

D 5.5.5.0 [90/2809856] via 172.16.34.4, 00:31:19, Serial0/2

172.16.0.0/24 is subnetted, 3 subnets

D 172.16.55.0 [90/2809856] via 172.16.34.4, 00:31:27, Serial0/2

D 172.16.45.0 [90/2681856] via 172.16.34.4, 00:31:58, Serial0/2

C 172.16.34.0 is directly connected, Serial0/2

10.0.0.0/24 is subnetted, 2 subnets

C 10.2.2.0 is directly connected, Serial0/1

10.1.1.0 [110/128] via 10.2.2.2, 00:29:57, Serial0/1

4. 在R5上配置分發列表過濾路由

R5(config)#ip access-list stan 10

R5(config-std-nacl)#10 deny 172.16.55.0

R5(config-std-nacl)#20 permit any

R5(config-std-nacl)#exit

R5(config)#router eigrp 90

R5(config-router)#distribute-list 10 out s0/3

R5(config-router)#end

R5#

*Mar 1 04:39:42.830: %SYS-5-CONFIG_I: Configured from console by console

R5#

*Mar 1 04:39:51.734: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 90: Neighbor 172.16.45.4 (Serial0/3) is resync: route configuration changed

當鄰居從新創建之後，再看R4的路由表

R4#show ip route

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 not set

1.0.0.0/24 is subnetted, 1 subnets

D EX 1.1.1.0 [170/2195456] via 172.16.34.3, 00:34:14, Serial0/2

2.0.0.0/24 is subnetted, 1 subnets

D EX 2.2.2.0 [170/2195456] via 172.16.34.3, 00:34:14, Serial0/2

33.0.0.0/24 is subnetted, 1 subnets

D 33.33.33.0 [90/2297856] via 172.16.34.3, 00:36:52, Serial0/2

3.0.0.0/24 is subnetted, 1 subnets

D EX 3.3.3.0 [170/2195456] via 172.16.34.3, 00:34:14, Serial0/2

4.0.0.0/24 is subnetted, 1 subnets

C 4.4.4.0 is directly connected, Loopback0

5.0.0.0/24 is subnetted, 1 subnets

D 5.5.5.0 [90/2297856] via 172.16.45.5, 00:36:08, Serial0/3

172.16.0.0/24 is subnetted, 2 subnets

C 172.16.45.0 is directly connected, Serial0/3

C 172.16.34.0 is directly connected, Serial0/2

10.0.0.0/24 is subnetted, 2 subnets

D EX 10.2.2.0 [170/2195456] via 172.16.34.3, 00:34:14, Serial0/2

D EX 10.1.1.0 [170/2195456] via 172.16.34.3, 00:34:14, Serial0/2

結果：R4上已經沒有了172.16.55.0的路由

5. 在R3上作路由彙總

R3(config)#int s0/2

R3(config-if)#ip summary-address eigrp 90 10.0.0.0 255.0.0.0

R3(config-if)#router ospf 110

R3(config-router)#summary-address 172.16.0.0 255.255.0.0

在R1和R5上分別看路由表

彙總前：

R1#show ip route

Gateway of last resort is not set

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

O 2.2.2.0 [110/65] via 10.1.1.2, 00:21:34, Serial0/0

33.0.0.0/24 is subnetted, 1 subnets

O E2 33.33.33.0 [110/20] via 10.1.1.2, 00:21:34, Serial0/0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/129] via 10.1.1.2, 00:21:34, Serial0/0

4.0.0.0/24 is subnetted, 1 subnets

O E2 4.4.4.0 [110/20] via 10.1.1.2, 00:21:34, Serial0/0

5.0.0.0/24 is subnetted, 1 subnets

O E2 5.5.5.0 [110/20] via 10.1.1.2, 00:21:34, Serial0/0

172.16.0.0/24 is subnetted, 3 subnets

O E2 172.16.55.0 [110/20] via 10.1.1.2, 00:21:37, Serial0/0

O E2 172.16.45.0 [110/20] via 10.1.1.2, 00:21:37, Serial0/0

O E2 172.16.34.0 [110/20] via 10.1.1.2, 00:21:37, Serial0/0

10.0.0.0/24 is subnetted, 2 subnets

O 10.2.2.0 [110/128] via 10.1.1.2, 00:21:37, Serial0/0

C 10.1.1.0 is directly connected, Serial0/0

彙總路由之後

R1#show ip rou

R1#show ip route

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

O 2.2.2.0 [110/65] via 10.1.1.2, 00:39:01, Serial0/0

33.0.0.0/24 is subnetted, 1 subnets

O E2 33.33.33.0 [110/20] via 10.1.1.2, 00:39:01, Serial0/0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/129] via 10.1.1.2, 00:39:01, Serial0/0

4.0.0.0/24 is subnetted, 1 subnets

O E2 4.4.4.0 [110/20] via 10.1.1.2, 00:39:01, Serial0/0

5.0.0.0/24 is subnetted, 1 subnets

O E2 5.5.5.0 [110/20] via 10.1.1.2, 00:39:01, Serial0/0

O E2 172.16.0.0/16 [110/20] via 10.1.1.2, 00:01:09, Serial0/0

10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks

O 10.2.2.0/24 [110/128] via 10.1.1.2, 00:39:01, Serial0/0

C 10.1.1.0/24 is directly connected, Serial0/0

O E2 10.0.0.0/8 [110/20] via 10.1.1.2, 00:01:37, Serial0/0

實驗結果：

在R1上看彙總路由的結果，通過彙總，確實把Eigrp傳過來的路由已經彙總成了172.16.0.0，可是，一樣在R1上能夠看到還有一條10.0.0.0/8的彙總路由，是從EIGRP重分佈過來的，實際上這是一條不須要的路由或者能夠說是產生了環路。

6. 在R3上作路由重分佈的過濾，防止環路的發生

解決環路，雙進行重分佈的路由器上面作分發列表，拒絕某路由協議域的彙總路由經過重分佈再回到該路由域

R3上的配置

router eigrp 90

redistribute ospf 110 metric 1544 100 255 1 1500

network 33.33.33.0 0.0.0.255

network 172.16.34.0 0.0.0.255

distribute-list 30 out ospf 110

no auto-summary

access-list 30 deny 172.16.0.0

access-list 30 permit any

!

router ospf 110

router-id 3.3.3.3

summary-address 172.16.0.0 255.255.0.0

redistribute eigrp 90 subnets tag 8888

network 3.3.3.0 0.0.0.255 area 0

network 10.2.2.0 0.0.0.255 area 0

distribute-list 20 out eigrp 90

!

access-list 20 deny 10.0.0.0

access-list 20 permit any

此時再查看R1的路由表，已經沒有了該條10.0.0.0/8的路由

R1#show ip route

1.0.0.0/24 is subnetted, 1 subnets

C 1.1.1.0 is directly connected, Loopback0

2.0.0.0/24 is subnetted, 1 subnets

O 2.2.2.0 [110/65] via 10.1.1.2, 01:00:35, Serial0/0

33.0.0.0/24 is subnetted, 1 subnets

O E2 33.33.33.0 [110/20] via 10.1.1.2, 01:00:35, Serial0/0

3.0.0.0/32 is subnetted, 1 subnets

O 3.3.3.3 [110/129] via 10.1.1.2, 01:00:35, Serial0/0

4.0.0.0/24 is subnetted, 1 subnets

O E2 4.4.4.0 [110/20] via 10.1.1.2, 01:00:35, Serial0/0

5.0.0.0/24 is subnetted, 1 subnets

O E2 5.5.5.0 [110/20] via 10.1.1.2, 01:00:35, Serial0/0

O E2 172.16.0.0/16 [110/20] via 10.1.1.2, 00:22:43, Serial0/0

10.0.0.0/24 is subnetted, 2 subnets

O 10.2.2.0 [110/128] via 10.1.1.2, 01:00:35, Serial0/0

C 10.1.1.0 is directly connected, Serial0/0

注意：在運行OSPF路由協議的路由器之間使用分發列表時，不容許使用接口上的out，容許使用接口in，可是使用接口in隻影響本臺路由器，對下游OSPF路由器是不會產生影響的，由於通告是LSA而不是路由。