Using the Area ID to Assign the OSPF Area Number
Attaching an Area to a Network
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NE2552E Application Guide for ENOS 8.4
The OSPF area number is defined in the areaid <IP address> option. The octet
format is used to be compatible with two different systems of notation used by
other OSPF network vendors. There are two valid ways to designate an area ID:
Single Number
Most common OSPF vendors express the area ID number as a single number.
For example, the Cisco IOS‐based router command "network 1.1.1.0
0.0.0.255 area 1" defines the area number simply as "area 1."
Multi‐octet (IP address): Placing the area number in the last octet (0.0.0.n)
Some OSPF vendors express the area ID number in multi‐octet format. For
example, "area 0.0.0.2" represents OSPF area 2 and can be specified directly
on the NE2552E as "area-id 0.0.0.2".
On the NE2552E, using the last octet in the area ID, "area 1" is equivalent to
"area-id 0.0.0.1".
Note: Although both types of area ID formats are supported, be sure that the area
IDs are in the same format throughout an area.
Once an OSPF area has been defined, it must be associated with a network. To
attach the area to a network, you must assign the OSPF area index to an IP interface
that participates in the area. The commands are as follows:
NE2552E(config)# interface ip
NE2552E(config-ip-if)# ip ospf area
NE2552E(config-ip-if)# exit
For example, the following commands could be used to configure IPv4 interface 14
for a presence on the IPv4 10.10.10.1/24 network, to define OSPF area 1, and to
attach the area to the network:
NE2552E(config)# router ospf
NE2552E(config-router-ospf)# area 1 area-id 0.0.0.1
NE2552E(config-router-ospf)# area 1 enable
NE2552E(config-router-ospf)# enable
NE2552E(config-router-ospf)# exit
i
NE2552E(config)#
nterface ip 14
NE2552E(config-ip-if)# ip address 10.10.10.1 255.255.255.0 enable
NE2552E(config-ip-if)# ip ospf area 1
NE2552E(config-ip-if)# ip ospf enable
Note:
OSPFv2 supports IPv4 only. IPv6 is supported in OSPFv3 (see "OSPFv3
Implementation in Lenovo ENOS" on page
<interface number>
<area index>
413).