Shulou(Shulou.com)06/01 Report--

OSPF virtual link: 1. Refers to the purpose of a virtual link connected to the backbone area through a non-backbone area: 1. Connect a region to the backbone area through a non-backbone area. Rules and characteristics of configuring virtual links through a non-backbone area connecting a segmented backbone area: 1. The virtual link must be configured between two ABR routers. The transfer area cannot be a stub area 3. The stability of the virtual link depends on the stability of the region it passes through. Virtual links help provide logical redundant virtual links configuration commands: Router (config-router) # area area-id vritual-link router-id virtual link configuration experiment: (the topology diagram in GNS3 is as follows)

Experimental environment preparation: GNS3 and its connected CRT1. After opening GNS3, we need to pull out four routers and two PCs. Area0 is the backbone area, area1 and area2 are the standard areas, 3.R2 is the virtual link in ABROSPF, which is the backbone area where we connect the area0 directly through a channel through the non-backbone area, just as if the area2 in the figure is directly connected to the area0, then the stability of this link depends on the stability of the area1. If the area1 is not stable, then the link is unstable. Next, let's take a look at the operation of virtual links. The first step: first configure the address of the route and declare the network segment: R1:R1#conf tR1 (config) # int f0lem0R1 (config-if) # ip add 192.168.10.1 255.255.255.0R1 (config-if) # no shutR1 (config-if) # int f0/1R1 (config-if) # ip add 192.168.20.1 255.255.255.0R1 (config-if) # no shutR1 (config-if) # exR1 (config) # int lo 0R1 ( Config-if) # ip add 1.1.1.1 255.255.255.255R1 (config-if) # no shutR1 (config-if) # ex R1 (config) # router ospf 1R1 (config-router) # router-id 1.1.1.1R1 (config-router) # network 192.168.10.0 0.0.0.255 area 2R1 (config-router) # network 192.168.20.0 0.0.255 area 2R2:R2#conf tR2 (config) # int f0/0R2 ( Config-if) # ip add 192.168.20.2 255.255.255.0R2 (config-if) # no shutR2 (config-if) # int f0/1R2 (config-if) # ip add 192.168.30.1 255.255.255.0R2 (config-if) # no shutR2 (config-if) # exR2 (config) # int lo 0R2 (config-if) # ip add 2.2.2.2 255.255.255.255 R2 (config-if) # no shutR2 (config-if) # ExR2 (config) # router ospf 1R2 (config-router) # router-id 2.2.2.2R2 (config-router) # network 192.168.20.0 0.0.0.255 area 2R2 (config-router) # network 192.168.30.0 0.0.0.255 area 1R2 (config-router) # ex Note: this is to achieve the verification effect. Do not configure virtual links for the time being! R3:R3#conf tR3 (config) # int f0/0R3 (config-if) # ip add 192.168.30.2 255.255.255.0R3 (config-if) # no shutR3 (config-if) # int f0/1R3 (config-if) # ip add 192.168.40.1 255.255.255.0R3 (config-if) # no shutR3 (config-if) # exR3 (config) # int lo 0R3 (config-if) # ip add 3.3.3.3 255.255.255. R3 (config-if) # no shutR3 (config-if) # exR3 (config) # router ospf 1R3 (config-router) # router-id 3.3.3.3R3 (config-router) # network 192.168.30.0 0.0.0.255 area 1R3 (config-router) # network 192.168.40.0 0.0.255 area 0R4:R4#conf tR4 (config) # int f0/0R4 (config-if) # ip add 192.168.40.2 255.255.255. 0R4 (config-if) # no shutR4 (config-if) # int f0/1R4 (config-if) # ip add 192.168.50.1 255.255.255.0R4 (config-if) # no shutR4 (config-if) # exR4 (config) # int lo 0R4 (config-if) # ip add 4.4.4.4 255.255.255.255R4 (config-if) # no shutR4 (config-if) # exR4 (config) # router ospf 1R4 (config- Router) # router-id 4.4.4.4R4 (config-router) # network 192.168.40.0 0.0.0.255 area 0R4 (config-router) # network 192.168.50.0 0.0.0.255 area 0 step 2: check whether the routers have learned network segments from each other: R1:R1 (config) # do show ip route. The parts 1.0.0.0 is subnetted 32 is directly connected, 1 subnetsC 1.1.1.1 is directly connected, Loopback0C 192.168.10 FastEthernet0/1R2:R2 24 is directly connected, FastEthernet0/0C 192.168.20.0 FastEthernet0/1R2:R2 24 do show ip route are omitted here. There is an omission of 2.0.0.0 subnetsC 32 is subnetted, 1 subnetsC 2.2.2.2 is directly connected, Loopback0C 192.168.30.0 via 24 is directly connected, FastEthernet0/1O 192.168.10.0 FastEthernet0/0O IA 192.168.20.1, 00:15:57, FastEthernet0/0O IA 192.168.40.0 FastEthernet0/0O IA 192.168.30.2, 192.168.30.2, FastEthernet0/1C 192.168.20.0 is directly connected 24 is directly connected, FastEthernet0/0O IA 192.168.50.0 is directly connected 24 [110 config 30] via 192.168.30.2, 00:03:29, FastEthernet0/1R3:R3 (config) # do show ip route. Omitted here is 3.0.0.0 subnetsC 32 is subnetted, 1 subnetsC 3.3.3.3 is directly connected, Loopback0C 192.168.30.0 is directly connected 24 is directly connected, FastEthernet0/0C 192.168.40.0 is directly connected 24 is directly connected, FastEthernet0/1O 192.168.50.0 FastEthernet0/1O 192.168.40.2, 00:10:35, FastEthernet0/1 Note: because we just did not configure virtual links in R2 So at this time R3 did not learn the network segment of the area2 area! R4:R4 (config) # do show ip route. The part O IA 192.168.30.0 via 192.168.40.1, 00:12:42, FastEthernet0/0 4.0.0.0 IP 32 is subnetted, 1 subnetsC 192.168.40.0 is directly connected 24 is directly connected, FastEthernet0/0C 192.168.50.0 is directly connected, FastEthernet0/1 step 3: enter two clients to configure the IP address and gateway. And test whether ping can be reached: PC1 > ip 192.168.10.2 192.168.10.1PC2 > ip 192.168.50.2 192.168.50.1PC1 > ping 192.168.50.2 * 192.168.10.1 icmp_seq=1 ttl=255 time=19.999 ms (ICMP type:3, code:1, Destination host unreachable) shows that the target host is unreachable and unreachable, so we need to make a virtual link at this time. To do this virtual link through the area1 area, it should be noted that when doing the virtual link, the router-id written is the other party's, how we should operate it, please continue to see. Step 4: configure the virtual link: return to R2:R2 (config) # router ospf 1R2 (config-router) # area1 virtual-link 3.3.3.3 / / area1 as the traversing area, write the router-id of R3 to R3:R3 (config) # router ospf 1R3 (config-router) # area1 virtual-link 2.2.2.2 / / area1 as the traversing area Write the router-id step 5 of R2: go back to the client to see if you can ping: PC1 > ping 192.168.50.2192.168.50.2 icmp_seq=1 timeout84 bytes from 192.168.50.2 icmp_seq=2 ttl=60 time=82.984 ms / / display status connectivity conclusion: at this time, in the case of full network interconnection, the routing table of each router learns all the network segments in the link. This shows that the setting of the virtual link can enable the standard area separated from the backbone area to intercommunicate with it in a non-directly connected state.

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