OSPF实验-20250922

组网需求

公司网络拓扑如下图所示：OSPF基础配置已经完成，作为网络管理员，有如下几个问题需要解决：

• 总公司与分公司A、B之间通信正常，但无法与办事处C通信。
• 分公司A的设备性能较低，希望降低路由计算、存储压力，同时考虑网络扩展，需要保留引入外部路由的功能。
• 办事处C外来人员较多，采用较安全的方式保证路由交互的安全性。
• RTA引入外部路由时除了考虑外部开销之外，还需要考虑OSPF域内的开销

组网拓扑

实验步骤

1. 配置接口IP、Loopback口IP
2. 配置OSPF区域、宣告网段（实现区域0、1、2互通）
3. RTC与RTE建立虚链接（实现区域3与其它区域互通）
4. 区域1配置为totally nssa（减少LSA泛洪）
5. RTE与RTF之间采用接口认证（Hello报文认证）
6. 区域1引用外部路由开销类型为1（总开销=外部开销+域内开销）

测试结果

VPC ping RTF的0/0接口

VPCS> ping 10.1.56.684 bytes from 10.1.56.6 icmp_seq=1 ttl=60 time=32.382 ms
84 bytes from 10.1.56.6 icmp_seq=2 ttl=60 time=3.926 ms
84 bytes from 10.1.56.6 icmp_seq=3 ttl=60 time=5.196 ms
84 bytes from 10.1.56.6 icmp_seq=4 ttl=60 time=6.113 ms
84 bytes from 10.1.56.6 icmp_seq=5 ttl=60 time=4.314 ms

查看RTB路由表，发现外部路由的开销是21，这里已经经过了1跳，N1表示NSSA外部路由类型1

SW2#show ip route Codes:  C - Connected, L - Local, S - StaticR - RIP, O - OSPF, B - BGP, I - IS-IS, V - Overflow routeN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2SU - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2IA - Inter area, EV - BGP EVPN, A - Arp to hostLA - Local aggregate route* - candidate defaultGateway of last resort is no set
C     2.2.2.2/32 is local host. 
C     10.1.24.0/24 is directly connected, GigabitEthernet 0/1
C     10.1.24.2/32 is local host. 
O IA  10.1.35.0/24 [110/2] via 10.1.123.3, 00:59:53, GigabitEthernet 0/0
O IA  10.1.56.0/24 [110/3] via 10.1.123.3, 00:50:33, GigabitEthernet 0/0
C     10.1.123.0/24 is directly connected, GigabitEthernet 0/0
C     10.1.123.2/32 is local host. 
O N1  192.168.10.0/24 [110/21] via 10.1.24.4, 00:13:42, GigabitEthernet 0/1

查看RTF路由表，发现外部路由开销是24，从拓扑看出刚好经过3跳，如果引用时的开销类型为2，这里的开销值应该是固定为20

SW6#show ip route Codes:  C - Connected, L - Local, S - StaticR - RIP, O - OSPF, B - BGP, I - IS-IS, V - Overflow routeN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2SU - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2IA - Inter area, EV - BGP EVPN, A - Arp to hostLA - Local aggregate route* - candidate defaultGateway of last resort is no set
C     6.6.6.6/32 is local host. 
O IA  10.1.24.0/24 [110/4] via 10.1.56.5, 00:25:53, GigabitEthernet 0/0
O IA  10.1.35.0/24 [110/2] via 10.1.56.5, 00:25:53, GigabitEthernet 0/0
C     10.1.56.0/24 is directly connected, GigabitEthernet 0/0
C     10.1.56.6/32 is local host. 
O IA  10.1.123.0/24 [110/3] via 10.1.56.5, 00:25:53, GigabitEthernet 0/0
O E1  192.168.10.0/24 [110/24] via 10.1.56.5, 00:15:45, GigabitEthernet 0/0

查看区域3交互报文，报文头部包含了认证秘钥

配置文件

RTA

hostname SW1
!
interface GigabitEthernet 0/0no switchportip address 10.1.123.1 255.255.255.0
!
interface Loopback 0ip address 1.1.1.1 255.255.255.255
!
router ospf 1graceful-restartnetwork 10.1.123.0 0.0.0.255 area 0
!

RTB

hostname SW2
!
interface GigabitEthernet 0/0no switchportip address 10.1.123.2 255.255.255.0
!
interface GigabitEthernet 0/1no switchportip address 10.1.24.2 255.255.255.0
!
interface Loopback 0ip address 2.2.2.2 255.255.255.255
!
router ospf 1graceful-restartarea 1 nssa no-summarynetwork 10.1.24.0 0.0.0.255 area 1network 10.1.123.0 0.0.0.255 area 0
!

RTC

hostname SW3
!
interface GigabitEthernet 0/0no switchportip address 10.1.123.3 255.255.255.0
!
interface GigabitEthernet 0/1no switchportip address 10.1.35.3 255.255.255.0
!
interface Loopback 0ip address 3.3.3.3 255.255.255.255
!
router ospf 1graceful-restartnetwork 10.1.35.0 0.0.0.255 area 2network 10.1.123.0 0.0.0.255 area 0area 2 virtual-link 5.5.5.5
!

RTD

hostname SW4
!
interface GigabitEthernet 0/0no switchportip address 10.1.24.4 255.255.255.0
!
interface GigabitEthernet 0/1no switchportip address 192.168.10.254 255.255.255.0
!
interface Loopback 0ip address 4.4.4.4 255.255.255.255
!
router ospf 1graceful-restartredistribute connected metric-type 1area 1 nssa no-summarynetwork 10.1.24.0 0.0.0.255 area 1
!

RTE

hostname SW5
!
key chain ospf-keykey 1key-string ruijie 
!
interface GigabitEthernet 0/0no switchportip address 10.1.35.5 255.255.255.0
!
interface GigabitEthernet 0/1no switchportip address 10.1.56.5 255.255.255.0ip ospf authentication keychain ospf-key
!
interface Loopback 0ip address 5.5.5.5 255.255.255.255
!
router ospf 1graceful-restartnetwork 10.1.35.0 0.0.0.255 area 2network 10.1.56.0 0.0.0.255 area 3area 2 virtual-link 3.3.3.3
!

RTF

hostname SW6
!
key chain ospf-keykey 1key-string ruijie 
!
interface GigabitEthernet 0/0no switchportip address 10.1.56.6 255.255.255.0ip ospf authentication keychain ospf-key
!
interface Loopback 0ip address 6.6.6.6 255.255.255.255
!         
router ospf 1graceful-restartnetwork 10.1.56.0 0.0.0.255 area 3
!