| 33.5. OSPF Areas table | ||
|---|---|---|
 | Chapter 33. OSPF - Open Shortest Path First |  |
| 33.5. OSPF Areas table | ||
|---|---|---|
| | Chapter 33. OSPF - Open Shortest Path First | |
The table of OSPF Areas can hold up to 16 definitions.
OSPF Area definitions are kept sorted. News definitions are added in the correct position of the table on the base of the currently defined entries. Likewise the entry deletion will cause the table to be rearranged.
Commands for managing the table of OSPF Areas are the following:
This command shows all currently defined OSPF ares:
[15:17:00] ABILIS_CPX:d ospf area
- Not Saved (SAVE CONF), Not Refreshed (INIT) ---------------------------------
--------------------------------------------------------
AREA: AUTTYPE: STUB: DEFCOST:
--------------------------------------------------------
001.001.000.001 CRYPTO NO 65535
001.001.000.002 SIMPLE YES 1
001.001.001.001 NO NO 65535
001.001.001.002 SIMPLE YES 65535
--------------------------------------------------------Meaning of the parameters:
AREAThis is a 32-bit number that identifies the area. The Area ID of 0.0.0.0 is reserved for the backbone. If the area represents a subnetted network, the IP network number of the subnetted network may be used for the Area ID.
AUTTYPEEach area can be configured for a separate type of authentication.
All OSPF protocol exchanges are authenticated. The OSPF packet header includes an authentication type field and 64-bits of data for use by the appropriate authentication scheme (determined by the type field). The authentication type is configurable on a per-area basis. Additional authentication data is configurable on a per-interface basis.
For example, if an area uses a simple password scheme for authentication, a separate password may be configured for each network contained in the area.
The current list of authentication types is described below:
NO - Use of this authentication type
means that routing exchanges in the area are not
authenticated. The 64-bit field in the OSPF header can contain
anything; it is not examined on packet reception.
SIMPLE - Using this authentication
type, a 64-bit field is configured on a per-network basis. All
packets sent on a particular network must have this configured
value in their OSPF header 64-bit authentication field. This
essentially serves as a "clear" 64-bit password.
CRYPTO - Using this authentication
type, a shared secret key is configured in all routers
attached to a common network/subnet. For each OSPF protocol
packet, the key is used to generate/verify a "message digest"
that is appended to the end of the OSPF packet. The message
digest is a one-way function of the OSPF protocol packet and
the secret key. Since the secret key is never sent over the
network in the clear, protection is provided against passive
attacks. The algorithm's used to generate and verify the
message digest are specified implicitly by the secret key.
This specification completely defines the use of OSPF
Cryptographic authentication when the MD5 algorithm is
used.
STUBWhether AS external advertisements will be flooded into/throughout the area. If AS external advertisements are excluded from the area, the area is called a "stub". Internal to stub areas, routing to external destinations will be based solely on a default summary route. The backbone cannot be configured as a stub area. Also, virtual links cannot be configured through stub areas.
DEFCOSTIf the area has been configured as a stub area, and the router itself is an area border router, then the Stub Default Cost indicates the cost of the default summary link that the router should advertise into the area.
This command adds a new entry to the OSPF Areas table, identified by the specified ID. The command also sets the eventually indicated optional parameters to the specified values.
[15:49:46] ABILIS_CPX:a ospf area:001.001.002.001 auttype:simple stub:no defcost:65535COMMAND EXECUTED [15:50:18] ABILIS_CPX:d ospf area- Not Saved (SAVE CONF), Not Refreshed (INIT) --------------------------------- -------------------------------------------------------- AREA: AUTTYPE: STUB: DEFCOST: -------------------------------------------------------- 001.001.000.001 CRYPTO NO 65535 001.001.000.002 SIMPLE YES 1 001.001.001.001 NO NO 65535 001.001.001.002 SIMPLE YES 65535 001.001.002.001 SIMPLE NO 65535 --------------------------------------------------------
The ID value unambiguously identifies an entry in the system. Two or more entries with the same ID value cannot be present at the same time in the table. If the indicated value matches an already existing entry, the following message will be displayed "OSPF AREA ALREADY EXISTS".
If the table is full, i.e. no free record is currently available, the message "OSPF AREAs TABLE IS FULL, COMMAND NOT EXECUTED" will be shown.
This command deletes an entry from the OSPF Areas table, identified by the specified ID.
[15:53:37] ABILIS_CPX:c ospf area:001.001.002.001COMMAND EXECUTED [15:53:47] ABILIS_CPX:d ospf area- Not Saved (SAVE CONF), Not Refreshed (INIT) --------------------------------- -------------------------------------------------------- AREA: AUTTYPE: STUB: DEFCOST: -------------------------------------------------------- 001.001.000.001 CRYPTO NO 65535 001.001.000.002 SIMPLE YES 1 001.001.001.001 NO NO 65535 001.001.001.002 SIMPLE YES 65535 --------------------------------------------------------
This command sets to new values the parameters of the OSPF Area, identified by the specified ID.
[15:53:50] ABILIS_CPX:s ospf area:001.001.000.001 auttype:simpleCOMMAND EXECUTED [15:55:20] ABILIS_CPX:d ospf area- Not Saved (SAVE CONF), Not Refreshed (INIT) --------------------------------- -------------------------------------------------------- AREA: AUTTYPE: STUB: DEFCOST: -------------------------------------------------------- 001.001.000.001 SIMPLE NO 65535 001.001.000.002 SIMPLE YES 1 001.001.001.001 NO NO 65535 001.001.001.002 SIMPLE YES 65535 --------------------------------------------------------
| |  | |
| 33.4. OSPF resource |  | 33.6. OSPF External Routes filter table |