思科OSPF的多区域配置及优化实验拓扑如上图所示各路由器配置接口IP地址，并均启用环回口，各路由器启用如图中的路由协议更改R3、R4的接口优先级为0，使得R2成为DR在R5上启用多个环回口，用于做路由汇总，配置如下：Loopback05.5.5.5Loopback1172.5.1.1Loopback2172.5.2.1Loopback3172.5.3.1在R9上启用多个环回口，用于做路由汇总，配置如下：Loopback09.9.9.9Loopback1172.16.1.1Loopback2172.16.2.1Loopback3172.16.3.1在R8上将EIGRP10的路由重发布到OSPF中，配置如下：router ospf 10log-adjacency-changesredistribute eigrp 10 metric-type 1 subnets在R8上使用ip default-network命令，给EIGRP10添加默认路由，配置如下：interface Loopback1ipaddress 192.168.8.1 255.255.255.0router eigrp 10network 192.168.8.0//将环回口所在的主类网段宣告进EIGRP中network 192.168.89.0noauto-summaryip default-network 192.168.8.0指定环回口所在网段为默认路由在R4上将RIP的路由重发布到OSPF中，配置如下：router ospf 10log-adjacency-changesredistribute rip metric-type 1 subnets在R4上向RIP域中宣告默认路由，配置如下：router ripversion 2network 192.168.47.0default-information originatenoauto-summary查看R9的路由表如下：Gateway of last resort is 192.168.89.8 tonetwork 192.168.8.0C192.168.89.0/24 is directly connected, Serial0/1D*192.168.8.0/24 [90/2297856] via 192.168.89.8, 01:04:43, Serial0/1172.16.0.0/24 is subnetted, 3 subnetsC172.16.1.0 is directly connected, Loopback1C172.16.2.0 is directly connected, Loopback2C172.16.3.0 is directly connected, Loopback39.0.0.0/24 is subnetted, 1 subnetsC9.9.9.0 is directly connected, Loopback0查看R7的路由表如下：Gateway of last resort is 192.168.47.4 tonetwork 0.0.0.0C192.168.47.0/24 is directly connected, Serial0/07.0.0.0/24 is subnetted, 1 subnetsC7.7.7.0 is directly connected, Loopback0R*0.0.0.0/0 [120/1] via 192.168.47.4, 00:00:22, Serial0/0查看R2的LSDB如下：R2#sh ip ospf daOSPF Router with ID (2.2.2.2) (Process ID 10)Router Link States (Area 0)Link IDADV RouterAgeSeq#Checksum Linkcount1.1.1.11.1.1.111090x80000006 0x00AFDD 3 2.2.2.22.2.2.210710x80000004 0x006D31 4 3.3.3.33.3.3.3300x80000006 0x002AF4 2 4.4.4.44.4.4.45200x80000007 0x0021EC 2 Net Link States (Area 0)Link IDADV RouterAgeSeq#Checksum192.168.1.22.2.2.210710x80000004 0x007822Summary Net Link States (Area0)Link IDADV RouterAgeSeq#Checksum5.5.5.51.1.1.111090x80000003 0x000DD46.6.6.64.4.4.410240x80000003 0x00844D8.8.8.81.1.1.18620x80000003 0x000590172.5.1.01.1.1.1600x80000001 0x00EB59 172.5.2.01.1.1.1600x80000001 0x00E063 172.5.3.01.1.1.1610x80000001 0x00D56D 192.168.15.01.1.1.111100x80000003 0x0092EB 192.168.46.04.4.4.410250x80000003 0x00E171 192.168.58.01.1.1.111100x80000003 0x003AD8 Summary ASB Link States (Area 0)Link IDADV RouterAgeSeq#Checksum8.8.8.81.1.1.18630x80000003 0x00ECA8Type-5 AS External Link StatesLink IDADV RouterAgeSeq#Checksum Tag7.7.7.04.4.4.45200x80000003 0x00EA0F 0 9.9.9.08.8.8.88810x80000003 0x002AB9 0 172.16.1.08.8.8.818850x80000002 0x00E061 0 172.16.2.08.8.8.816440x80000002 0x00D56B 0 172.16.3.08.8.8.816440x80000002 0x00CA75 0 192.168.8.08.8.8.88810x80000003 0x006528 0 192.168.47.04.4.4.45200x80000003 0x002F47 0 192.168.89.08.8.8.88810x80000003 0x00E655 0查看R2的路由表如下：Gateway of last resort is not setO E1 192.168.89.0/24 [110/212] via192.168.12.1, 00:01:03, Serial0/0O IA 192.168.46.0/24 [110/65] via192.168.1.4, 00:29:57, FastEthernet1/0C192.168.12.0/24 is directly connected, Serial0/01.0.0.0/32 is subnetted, 1 subnetsO1.1.1.1 [110/65] via 192.168.12.1, 00:29:57, Serial0/0O E1 192.168.47.0/24 [110/21] via192.168.1.4, 00:01:03, FastEthernet1/02.0.0.0/24 is subnetted, 1 subnetsC2.2.2.0 is directly connected, Loopback03.0.0.0/32 is subnetted, 1 subnetsO3.3.3.3 [110/2] via 192.168.1.3, 00:29:57, FastEthernet1/0O IA 192.168.15.0/24 [110/128] via192.168.12.1, 00:29:57, Serial0/0O E1 192.168.8.0/24 [110/212] via192.168.12.1, 00:01:03, Serial0/04.0.0.0/32 is subnetted, 1 subnetsO4.4.4.4 [110/2] via 192.168.1.4, 00:29:58, FastEthernet1/0O IA 192.168.58.0/24 [110/192] via192.168.12.1, 00:29:58, Serial0/05.0.0.0/32 is subnetted, 1 subnetsO IA5.5.5.5 [110/129] via 192.168.12.1, 00:29:58, Serial0/06.0.0.0/32 is subnetted, 1 subnetsO IA6.6.6.6 [110/66] via 192.168.1.4, 00:29:58, FastEthernet1/0172.5.0.0/24 is subnetted, 3 subnetsO IA172.5.1.0 [110/129] via 192.168.12.1, 00:00:05, Serial0/0172.5.3.0 [110/129] via 192.168.12.1, 00:00:05, Serial0/0 O IA172.5.2.0 [110/129] via 192.168.12.1, 00:00:05, Serial0/0172.16.0.0/24 is subnetted, 3 subnetsO E1172.16.1.0 [110/212] via 192.168.12.1, 00:00:00, Serial0/0 O E1172.16.2.0 [110/212] via 192.168.12.1, 00:00:00, Serial0/0 O E1172.16.3.0 [110/212] via 192.168.12.1, 00:00:00, Serial0/07.0.0.0/24 is subnetted, 1 subnetsO E17.7.7.0 [110/21] via 192.168.1.4, 00:00:00, FastEthernet1/08.0.0.0/32 is subnetted, 1 subnetsO IA8.8.8.8 [110/193] via 192.168.12.1, 00:29:58, Serial0/09.0.0.0/24 is subnetted, 1 subnets9.9.9.0 [110/212] via 192.168.12.1, 00:00:00, Serial0/0C192.168.1.0/24 is directly connected, FastEthernet1/0查看R5的路由表如下：Gateway of last resort is not setO E1 192.168.89.0/24 [110/84] via192.168.58.8, 00:22:06, Serial0/0O IA 192.168.46.0/24 [110/193] via192.168.15.1, 00:49:13, Serial0/1O IA 192.168.12.0/24 [110/128] via192.168.15.1, 00:49:13, Serial0/11.0.0.0/32 is subnetted, 1 subnetsO IA1.1.1.1 [110/65] via 192.168.15.1, 00:49:13, Serial0/1O E1 192.168.47.0/24 [110/149] via192.168.15.1, 00:22:06,Serial0/12.0.0.0/32 is subnetted, 1 subnetsO IA2.2.2.2 [110/129] via 192.168.15.1, 00:49:13, Serial0/13.0.0.0/32 is subnetted, 1 subnetsO IA3.3.3.3 [110/130] via 192.168.15.1, 00:22:11, Serial0/1C192.168.15.0/24 is directly connected, Serial0/1O E1 192.168.8.0/24 [110/84] via192.168.58.8, 00:22:06, Serial0/04.0.0.0/32 is subnetted, 1 subnetsO IA4.4.4.4 [110/130] via 192.168.15.1, 00:49:14, Serial0/1C192.168.58.0/24 is directly connected, Serial0/05.0.0.0/24 is subnetted, 1 subnetsC5.5.5.0 is directly connected, Loopback06.0.0.0/32 is subnetted, 1 subnetsO IA6.6.6.6 [110/194] via 192.168.15.1, 00:49:14, Serial0/1172.5.0.0/24 is subnetted, 3 subnetsC172.5.1.0 is directly connected, Loopback1C172.5.3.0 is directly connected, Loopback3C172.5.2.0 is directly connected,Loopback2172.16.0.0/24 is subnetted, 3 subnetsO E1172.16.1.0 [110/84] via 192.168.58.8, 00:22:06, Serial0/0 O E1172.16.2.0 [110/84] via 192.168.58.8, 00:22:06, Serial0/0 O E1172.16.3.0 [110/84] via 192.168.58.8, 00:22:06, Serial0/07.0.0.0/24 is subnetted, 1 subnetsO E17.7.7.0 [110/149] via 192.168.15.1, 00:22:06, Serial0/18.0.0.0/32 is subnetted, 1 subnetsO8.8.8.8 [110/65] via 192.168.58.8, 00:49:14, Serial0/09.0.0.0/24 is subnetted, 1 subnetsO E19.9.9.0 [110/84] via 192.168.58.8, 00:22:06, Serial0/0O IA 192.168.1.0/24 [110/129] via192.168.15.1, 00:49:14, Serial0/1发现各路由器的LSDB和路由表都比较庞大，进行优化1、在ABR路由器R1上做区域间路由汇总，配置如下：router ospf 10log-adjacency-changesarea2 range 172.5.0.0 255.255.252.02、在ASBR路由器R8上做外部路由汇总，配置如下：router ospf 10log-adjacency-changessummary-address 172.16.0.0 255.255.252.03、将OSPF area2更改为 total NSSA区域，配置如下：在R5、R8的ospf进程下，配置如下命令：area 2 nssa在R1的ospf进程下，配置如下命令：area 2 nssa no-summary//加入参数no-summary，将禁止外部（5类）LSA和汇总（3类和4类）LSA进入区域，而用一条默认路由代替。