area

Configures OSPF network areas (OSPF enables interfaces). An OSPF network can be subdivided into routing areas to simplify administration and optimize traffic utilization. Areas are logical groupings of hosts and networks, including routers having interfaces connected to an included network. Each area maintains a separate link state database whose information may be summarized towards the rest of the network by the connecting router. Areas are identified by 32-bit IDs, expressed either in decimal, or octet-based dot-decimal notation. Areas can defined as: stub area, totally-stub, non-stub, nssa, totally nssa. Each of these area types have been discussed further in the area-type topic of this chapter.

At least one default area, bearing number ‘0‘, should be configured for every OSPF network. In case of multiple areas, the default area 0 forms the backbone of the network. The default area 0 is used as a link to the other areas. Each area has its own link-state database.

A router running OSPF sends hello packets to discover neighbors and elect a designated router. The hello packet includes link state information and list of neighbors. OSPF is savvy with layer 2 topologies. If on a point-to-point link, OSPF knows it is sufficient, and the link stays up. If on a broadcast link, the router waits for election before determining if the link is functional.

Supported in the following platforms:

Syntax

area [<0-4294967295>|<IP>]

Parameters

area [<0-4294967295>|<IP>]
area Defines an OSPF area
<0-4294967295> Defines an OSPF area in the form of a 32 bit integer
  • <0-4294967295> – Specify the value from 0 - 4294967295.
<IP> Defines an OSPF area in the form of an IP address
  • <IP> – Specify the IP address.

Examples

nx9500-6C8809(config-profile default-ap8533-router-ospf)#area 4
nx9500-6C8809(config-profile default-ap8533-router-ospf-area-0.0.0.4)#?
Router OSPF Area Mode commands:
  area-type       OSPF area type
  authentication  Authentication scheme for OSPF area
  no              Negate a command or set its defaults
  range           Routes matching this range are considered for summarization
                  (ABR only)

  clrscr          Clears the display screen
  commit          Commit all changes made in this session
  do              Run commands from Exec mode
  end             End current mode and change to EXEC mode
  exit            End current mode and down to previous mode
  help            Description of the interactive help system
  revert          Revert changes
  service         Service Commands
  show            Show running system information
  write           Write running configuration to memory or terminal

nx9500-6C8809(config-profile default-ap8533-router-ospf-area-0.0.0.4)#
nx9500-6C8809(config-profile default-ap8533-router-ospf-area-0.0.0.4)#show context
  area 0.0.0.4
nx9500-6C8809(config-profile default-ap8533-router-ospf-area-0.0.0.4)#

Related Commands

The following table summarizes the OSPF area configuration mode commands:
Table 1. OSPF-Area-Mode Commands
Command Description
area-type Configures a particular OSPF area as STUB or NSSA
authentication Specifies the authentication scheme used for the OSPF area
range Specifies the routes matching address/mask for summarization
no (area-config-mode-command) Removes this area settings
no (router-mode-config-command) Removes this area configuration from the router mode policy