Basic configuration of OSPF virtual links

Basic configuration of OSPF virtual links

One: the principle of OSPF virtual link

Refers to a logical connection channel established between two ABR through a non-backbone area (which must be configured on both ends of the ABR). Establish a virtual link between the two routers R1 and R2, so that there is a logical link between area2 and area0, and area1 is the translation area. The figure below is as follows

Logical channel means that other routers running OSPF between two ABR simply forward messages, which is equivalent to forming a point-to-point connection between two ABR.

Second: the purpose of the virtual link

Connect a region to a backbone area through a non-backbone area

Connect a segment to the backbone area through a non-backbone area

Third, configure the characteristics of virtual links:

1. The virtual link must be configured between two ABR routers

2. The transfer area cannot be a stub area

3. The stability of the virtual link depends on the stability of the area it passes through.

4. Virtual connections help to provide logical redundancy

Four: experimental configuration

1. Pull out four routers and two hosts in GNS3 and connect them to each other, mark the interface label and interface address of each point, and mark the backbone area and non-backbone area. The figure below is as follows

2. First configure four routers, the interface address on the router must be configured first, and then configure the OSPF routing protocol. The 10 network segment on R4 is declared into area2, and the 50 network segment on R3 is declared into area0. Finally, a virtual link between R1 and R2 is established.

R4

R1, R2, and R3 are the same as R4, first configure the address of each interface, then create a virtual loopback interface and configure the address, and finally configure the ospf routing protocol to determine which area the interface on each router belongs to.

3. Finally, the virtual links of R1 and R2 are established. If area2 wants to communicate with area0, it must go through area1, so area1 is the traversing area.

R1

R2

4. After the configuration is complete, add the ip address to the two hosts and verify whether they can communicate with each other.

Can communicate with each other, this experiment is completed.