Assigning an area range (optional)
You can assign a range for an area, but it is not required. Ranges allow a specic IP address and mask to represent a range of IP
addresses within an area, so that only that reference range address is advertised to the network, instead of all the addresses within that
range. Each area can have up to 32 range addresses.
To dene an area range for subnets on 10.45.5.1 and 10.45.6.2, enter the following command.
device(config)# router ospf
device(config-ospf-router)# area 10.45.5.1 range 10.45.0.0 255.255.0.0
device(config-ospf-router)# area 10.45.6.2 range 10.45.0.0 255.255.0.0
Syntax: [no] area { num | ip-addr } range ip-addr ip-mask
The num and ip-addr parameters specify the area number, which can be in IP address format.
The range ip-addr parameter species the IP address portion of the range. The software compares the address with the signicant bits in
the mask. All network addresses that match this comparison are summarized in a single route advertised by the router.
The ip-mask parameter species the portions of the IP address that a route must contain to be summarized in the summary route. In the
example above, all networks that begin with 10.45 are summarized into a single route.
Assigning an area cost (optional parameter)
You can assign a cost for an area, but it is not required. To consolidate and summarize routes at an area boundary, use the area range
cost command in router
conguration mode.
If the cost parameter is specied, it will be used (overriding the computed cost) to generate the summary LSA. If the cost parameter is
not specied, then the existing range metric computation max or min cost of routes falling under this range will be used to generate
summary LSA.
NOTE
The area should be already congured before using this
command.
Creates an area range entry with ip address 10.1.1.1 and network mask 255.255.255.0 with the area-id 10.
device(config)# router ospf
device(config-ospf-router)# area 10 range 10.1.1.1 255.255.255.0
Modies the address range status to DoNotAdvertise . Neither the individual intra-area routes falling under range nor the ranged prex is
advertised as summary LSA.
device(config)# router ospf
device(config-ospf-router)# area 10 range 10.1.1.1 255.255.255.0 not-advertise
Modies the address range status to advertise and a Type 3 summary link-state advertisement (LSA) can be generated for this address
range.
device(config)# router ospf
device(config-ospf-router)# area 10 range 10.1.1.1 255.255.255.0 advertise
Modies the address range status to advertise and assign cost for this area range to 10.
device(config)# router ospf
device(config-ospf-router)# area 10 range 10.1.1.1 255.255.255.0 advertise cost 10
Modies the address range status to not-advertise and cost from 10 to 5.
device(config)# router ospf
device(config-ospf-router)# area 10 range 10.1.1.1 255.255.255.0 not-advertise cost 5
Conguring OSPF
FastIron Ethernet Switch Layer 3 Routing
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