Syntax:
area[[ospf-area-id] | [backbone]] range [[ip-addr/mask-length]] [no-advertise] [type summary [[cost 1-16777215] | [nssa] | [cost 1-16777215]]]
area[no-advertise] [type summary[[cost 1-16777215] | nssa ]]ospf-area-idrange ip-addr/mask-length
Use this command on a routing switch intended to operate as an ABR for the specified area to do either of the following:
-
Simultaneously create the area and corresponding range setting for routes to summarize or block.
-
For an existing area, specify a range setting for routes to summarize or block.
Options
Same area ID as in Configuring an OSPF backbone or normal area, except you cannot assign a backbone area number (
0or0.0.0.0) to a stub or NSSA area.
Defines the range of route advertisements to either summarize for injection into the backbone area or to prevent from being injected into the backbone area. The
ip-addrvalue specifies the IP address portion of the range, andmask-lengthspecifies the leftmost significant bits in the address. The ABR for the specified area compares the IP address of each outbound route advertisement with the address and significant bits in the mask to determine which routes to select for either summarizing or blocking. For example, a range of 10.10.32.1/14 specifies all routes in the range of 10.10.32.1 - 10.10.35.254.
Use this keyword only if you want to configure the ABR to prevent advertisement to the backbone of a specified range of routes. (This has the effect of "hiding" the specified range from the backbone area.) If you do not use this option, the ABR advertises the specified range of routes according to the
type summary | nssaselection described below.
[type summary [[cost 1-16777215] | nssa ]]
Configures the type of route summaries to advertise or block.
If the option
typeis not used in the command, the ABR defaults this setting to summary.The option
type summary [cost 1-16777215]specifies internal routes in the configured range of RAs and the user-configured cost for an area summary range. If cost is specified, the range will advertise the specified cost instead of the calculated cost.If
[no] advertiseis used in the command, the ABR prevents the selected internal routes from being summarized in a type-3 LSA and advertised to the backbone.If
no-advertiseis not used in the command, the selected routes are summarized to the backbone in a type-3 LSA.Option
nssaspecifies external routes (type-7 LSAs) in the configured range of route advertisements. Ifno-advertise(above) is used in the command, the ABR prevents the selected external routes from being summarized in a type-5 LSA and advertised to the backbone. (Configure this option where an ABR for an NSSA advertises external routes that you do not want propagated to the backbone.)If
no-advertiseis not used in the command, the selected routes learned from type-7 LSAs in the area are summarized to the backbone in a type-5 LSA.[cost 1-16777215]User configured cost for an NSSA summary range. If cost is not configured, the ABR will use the algorithm defined in RFC 3101 to compute the cost and metric-type of the summarized route. If cost is specified, then the range will advertise the specified cost as the cost of the summarized route.
The cost parameter provides a way to define a fixed, user-assigned cost of an LSA type 3 summarized prefix.
Setting a summary cost to an area
This example shows how to set the summary cost to 100 for area 10 with an address range of 10.10.0.0/16.
HP Switch(ospf)# area 10 range 10.10.0.0/16 type summary cost 100
Using a standard summary cost for an area
This example shows how to use the standard method for determining the summarized cost.
HP Switch(ospf)# area 10 range 10.10.0.0/16 type summary
You must execute write mem to preserve these settings across reboots.
Setting a summary cost to an NSSA area
To set the summary cost for NSSA area 20 address range 10.20.0.0/16 to 100 with a default metric-type of type2, enter the following command.
HP Switch(ospf)# area 20 range 10.20.0.0/16 type nssa cost 100
Setting a summary cost and metric-type to an NSSA area
To set the summary cost and metric-type for NSSA area 20 address range 10.20.0.0/16 to 100, enter the following command.
HP Switch(ospf)# area 10 range 10.10.0.0/16 type nssa cost 100 metric-type type1
Using the RFC standard ethod to determine the summarized cost to an NSSA area
To change the configuration so that the 10.20.0.0/16 range uses the RFC standard method for determining the summarized cost, enter the following command.
HP Switch(ospf)# area 10 range 10.10.0.0/16 type nssa
You must execute write mem to preserve these settings across reboots.
Output showing settings for summary costs
The show ip ospf command displays information about summary costs. An entry of auto indicates that the cost is calculated by the OSPF standard for summarized networks.
HP Switch(config)# show ip ospf OSPF Configuration Information : : Currently defined address ranges: Area ID LSA Type IP Network Network Mask Advertise Cost --------------- ---------- --------------- --------------- --------- -------- 0.0.0.10 Summary 10.10.0.0 255.255.0.0 yes auto 0.0.0.20 NSSA 10.20.0.0 255.255.0.0 yes auto 0.0.0.30 Summary 10.30.0.0 255.255.0.0 no 16777215
Defining a range of internal routes to advertise to the backbone
The commands in this example define the same range of internal routes in area 30 to summarize for injection into the backbone area. (In this example, area 30 can be a normal or stub area, or an NSSA.)
HP Switch(ospf)# area 30 range 10.0.0.0/8 HP Switch(ospf)# area 30 range 10.0.0.0/8 type summary
Defining a range of internal routes to block from advertising to the backbone
For the same range of routes, you can use either of the following commands to block injection of a range of summary routes (type-3 LSAs) from area 30 into the backbone.
HP Switch(config)# area 30 range 10.0.0.0/8 type no-advertise HP Switch(config)# area 30 range 10.0.0.0/8 type no-advertise summary
Example of allowing or blocking a range of external RAs to the backbone
This example applies only to external routes that can be advertised from an NSSA to the backbone. The first command defines the range of external routes in the Area 7 NSSA to advertise to the backbone. The second command defines the range of external routes in the Area 7 NSSA to block from advertising to the backbone.
HP Switch(config)# area 7 range 192.51.0.0/16 type nssa HP Switch(config)# area 7 range 192.51.0.0/16 no-advertise type nssa