Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 664)

636 Multi-Service IronWare Routing Configuration Guide
53-1003033-02
Configuring OSPFv3
When you disable the summary LSAs, the change takes effect immediately. If you apply the option
to a previously configured area, the device flushes all of the summary LSAs it has generated (as an
ABR) from the area.
NOTE
This feature applies only when the device is configured as an Area Border Router (ABR) for the area.
To completely prevent summary LSAs from being sent to the area, disable the summary LSAs on
each OSPF router that is an ABR for the area.
For example, to disable summary LSAs for stub area 40 and specify an additional metric of 99,
enter the following command.
Brocade(config-ospf6-router)# area 40 stub 99 no-summary
Syntax: [no] area number | ipv6-address stub metric [no-summary]
The number | ipv6-address parameter specifies the area number, which can be a number or in
IPv6 address format. If you specify a number, the number can be from 0 through 2,147,483,647.
The stub metric parameter specifies an additional cost for using a route to or from this area and
can be from 1 through 16777215. There is no default. Normal areas do not use the cost
parameter.
The no-summary parameter applies only to stub areas and disables summary LSAs from being sent
into the area.
Assign a Not-So-Stubby Area (NSSA)
The OSPF Not So Stubby Area (NSSA) feature enables you to configure OSPF areas that provide the
benefits of stub areas, but that also are capable of importing external route information. OSPF
does not flood external routes from other areas into an NSSA, but does translate and flood route
information from the NSSA into other areas such as the backbone.
NSSAs are especially useful when you want to summarize Type-5 External LSAs (external routes)
before forwarding them into an OSPF area. The OSPF specification (RFC 2328) prohibits
summarization of Type-5 LSAs and requires OSPF to flood Type-5 LSAs throughout a routing
domain. When you configure an NSSA, you can specify an address range for aggregating the
external routes that the NSSAs ABR exports into other areas.
Since the NSSA is partially “stubby” the ABR does not flood external LSAs from the backbone into
the NSSA. To provide access to the rest of the Autonomous System (AS), the ABR generates a
default Type-7 LSA into the NSSA.
Configuring an NSSA
Using the area area-id nssa command, you can block the generation of type-3 and type-7 LSAs into
an NSSA. This command also provides an option to configure the NSSA translator role.
Configuration examples
The following example creates an NSSA area with an area-id 100. If the router is an ABR then a
type-3 summary LSA will be originated into the NSSA area and if the router is an ASBR then type-7
NSSA external LSA will be generated into NSSA area with a default external metric value of 10. The
routers NSSA translator role will be set to candidate and it will participate in NSSA translation
election.
Brocade(config-ospf6-router)# area 100 nssa