OSPF Area Range Configuration Guide

OSPF should aggregate route entries from the backbone area into a non-backbone area or from a non-backbone area into the backbone area. Route aggregation works only on the ABR.

User can use the "advertise disable" parameter to restrain route aggregation at the ABR. The ABR will aggregate routes by default after area-range is configured and the packet is routed to the best (the longest or most specific) match.

Figure 5-6. OSPF area range configuration.

Configuring Switch A

admin@XorPlus# set vlans vlan-id 500 l3-interface vlan-500 
admin@XorPlus# set vlan-interface interface vlan-500 vif vlan-500 address 192.168.1.2 prefix-length 30
admin@XorPlus# set interface gigabit-ethernet te-1/1/49 family ethernet-switching native-vlan-id 500
admin@XorPlus# set protocols ospf4 router-id 1.1.1.1
admin@XorPlus# set protocols ospf4 area 0.0.0.0 interface vlan-500 vif vlan-500 address 192.168.1.2
admin@XorPlus#commit
Waiting for merging configuration.
Commit OK.
Save Done.
admin@XorPlus#

Configuring Switch B

admin@XorPlus# set vlans vlan-id 500 l3-interface vlan-500
admin@XorPlus# set vlan-interface interface vlan-500 vif vlan-500 address 192.168.1.1 prefix-length 30
admin@XorPlus# set interface gigabit-ethernet te-1/1/49 family ethernet-switching native-vlan-id 500
admin@XorPlus# set protocols ospf4 router-id 4.4.4.4
admin@XorPlus# set protocols ospf4 area 0.0.0.0 interface vlan-500 vif vlan-500 address 192.168.1.1
admin@XorPlus# set vlans vlan-id 400 l3-interface vlan-400
admin@XorPlus# set vlan-interface interface vlan-400 vif vlan-400 address 172.25.150.250 prefix-length 30
admin@XorPlus# set interface gigabit-ethernet te-1/1/50 family ethernet-switching native-vlan-id 400
admin@XorPlus# set protocols ospf4 area 1.1.1.1 interface vlan-400 vif vlan-400 address 172.25.150.250
admin@XorPlus#commit
Waiting for merging configuration.
Commit OK.
Save Done.
admin@XorPlus#

Configuring Switch C

admin@XorPlus# set vlans vlan-id 400 l3-interface vlan-400
admin@XorPlus# set vlan-interface interface vlan-400 vif vlan-400 address 172.25.150.249 prefix-length 30
admin@XorPlus# set interface gigabit-ethernet te-1/1/49 family ethernet-switching native-vlan-id 400
admin@XorPlus# set protocols ospf4 router-id 3.3.3.3
admin@XorPlus# set protocols ospf4 area 1.1.1.1 interface vlan-400 vif vlan-400 address 172.25.150.249
admin@XorPlus#commit
Waiting for merging configuration.
Commit OK.
Save Done.
admin@XorPlus#

Checking the route table on Switch C

There will be a 30-bit route entry,192.168.1.0/30.

admin@Xorplus# run show route forward-route ipv4 all 
Destination          NextHopMac          Port    
---------------      -----------------   ---------
172.25.150.248/30    60:EB:69:44:44:44   connected
192.168.1.0/30       A8:2B:B5:E0:94:A7   te-1/1/49
Total route count:2

Configuring area-range on ABR(Switch B)

admin@XorPlus# set protocols ospf4 area 0.0.0.0 area-range 192.168.1.0/24 advertise true
admin@XorPlus# commit
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Checking the route table on Switch C

The route entry 192.168.1.0/30 will be replaced by 192.168.1.0/24.

admin@Xorplus# run show route forward-route ipv4 all 
Destination          NextHopMac          Port    
---------------      -----------------   ---------
172.25.150.248/30    60:EB:69:44:44:44   connected
192.168.1.0/24       A8:2B:B5:E0:94:A7   te-1/1/49
Total route count:2