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Alteon OS Application Guide
Chapter 12: OSPF
19542C4911, January 2007
Using the Area ID to Assign the OSPF Area Number
The OSPF area number is defined in the areaid <IP address> option. The octet format is
used in order to be compatible with two different systems of notation used by other OSPF net-
work vendors. There are two valid ways to designate an area ID:
Placing the area number in the last octet (0.0.0.n)
Most common OSPF vendors express the area ID number as a single number. For exam-
ple, 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.” On the GbE Switch Module, using the last
octet in the area ID, “area 1” is equivalent to “areaid 0.0.0.1”.
Multi-octet (IP address)
Some OSPF vendors express the area ID number in multi-octet format. For example,
“area 2.2.2.2” represents OSPF area 2 and can be specified directly on the GbE
Switch Module as “areaid 2.2.2.2”.
NOTE – Although both types of area ID formats are supported, be sure that the area IDs are in
the same format throughout an area.
Attaching an Area to a Network
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 format for the command is as follows:
For example, the following commands could be used to configure IP interface 14 for a pres-
ence on the 10.10.10.1/24 network, to define OSPF area 1, and to attach the area to the net-
work:
>> # /cfg/l3/ospf/if <interface number>/aindex <area index>
>> # /cfg/l3/if 14 (Select menu for IP interface 14)
>> IP Interface 14# addr 10.10.10.1 (Define IP address on backbone
network)
>> IP Interface 14# mask 255.255.255.0 (Define IP mask on backbone)
>> IP Interface 14# ena (Enable IP interface 14)
>> IP Interface 14# ../ospf/aindex 1
(Select menu for area index 1)
>> OSPF Area (index) 1 # areaid 0.0.0.1
(Define area ID as OSPF area 1)
>> OSPF Area (index) 1 # ena (Enable area index 1)
>> OSPF Area (index) 1 # ../if 14 (Select OSPF menu for interface 14)
>> OSPF Interface 14# aindex 1 (Attach area to network on interface
14)
>> OSPF Interface 14# enable (Enable interface 14 for area index 1)