OSPF
Example 2: Virtual links
In the example shown in the following figure, area 2 is not physically connected to the backbone as is usually required. Instead, area 2 will be connected to the backbone via a virtual link through area 1. The virtual link must be configured at each endpoint.
Figure 22 Configuring a virtual linkConfiguring OSPF for a virtual link on Switch A
1.Configure IP interfaces on each network that will be attached to the switch.In this example, two IP interfaces are needed on Switch A: one for the backbone network on 10.10.7.0/24 and one for the transit area network on 10.10.12.0/24.
>> # /cfg/l3/if | 1 | (Select menu | for IP interface 1) | |
>> IP Interface | 1 | # addr 10.10.7.1 | (Set IP | address on backbone network) |
>> IP Interface | 1 | # mask 255.255.255.0 (Set | IP mask on backbone network) | |
>> IP Interface | 1 | # enable | (Enable | IP interface 1) |
>> IP Interface | 1 | # ../if 2 | (Select | menu for IP interface 2) |
>> IP Interface | 2 | # addr 10.10.12.1 (Set IP | address on | |
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| transit area network) | |
>> IP Interface | 2 | # mask 255.255.255.0 (Set IP mask on | ||
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| transit area network) | |
>> IP Interface | 2 | # enable | (Enable interface 2) |
3.A router ID is required when configuring virtual links. Later, when configuring the other end of the virtual link on Switch B, the router ID specified here will be used as the target virtual neighbor (nbr)
address>> IP Interface 2 # /cfg/l3/rtrid 10.10.10.1 | (Set static router ID) |
>>IP # /cfg/l3/ospf/on
5.Define the backbone.>> Open Shortest Path First # | aindex 0 | (Select | menu for area index 0) | |||
>> OSPF Area (index) 0 | # areaid 0.0.0.0 | (Set the area ID) | ||||
>> OSPF Area (index) | 0 | # | type | transit | (Define backbone as transit type) | |
>> OSPF Area (index) | 0 | # | enable | (Enable | the area) |
>> OSPF Area (index) 0 | # ../aindex 1 | (Select menu for area index 1) | ||
>> OSPF Area (index) 1 | # areaid 0.0.0.1(Set the area ID for OSPF area 1) | |||
>> OSPF Area (index) | 1 | # | type transit | (Define area as transit type) |
>> OSPF Area (index) | 1 | # | enable | (Enable the area) |
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| 150 |