Administrator Guide

OSPF Area 0 — Te 2/1 and 2/2
router ospf 22222
network 192.168.100.0/24 area 0
network 10.2.21.0/24 area 0
network 10.2.22.0/24 area 0
!
interface Loopback 20
ip address 192.168.100.20/24
no shutdown
!
interface TengigabitEthernet 2/1
ip address 10.2.21.2/24
no shutdown
!
interface TengigabitEthernet 2/2
ip address 10.2.22.2/24
no shutdown
OSPFv3 NSSA
NSSA (Not-So-Stubby-Area) is a stub area that does not support Type-5 LSAs, but supports Type-7 LSAs to forward external
links. Initially ASBR (Autonomous System Border Router) forwards the external links through Type-7 LSAs to the Area Border
Router (ABR) of NSSA, which in turn converts them into Type-5 LSAs and forwards them to the rest of the OSPF domain.
NOTE: To support NSSA area, all the OSPF routers in that area should be configured with NSSA.
NSSA Options
NSSA can be configured with the following options:
1. Default-information-originate – To inject a default route using Type-7 LSAs — NSSA routers need to have access to the rest
of the OSPF routers in the autonomous system. To facilitate this, the default route is injected into the NSSA area through a
Type-7 LSA. This can be generated either by NSSA ASBR or NSSA ABR.
2. No-redistribute – To restrict Type-7 LSAs — When NSSA ASBR is also an ABR, redistributed external routes need not be
translated from Type-7 to Type-5 LSAs. ABR will directly inject external routes through Type-5 LSAs into the OSPF domain.
It does not send Type-7 LSAs into the NSSA area.
3. No-summary – To act as totally stubby area — NSSA area can be converted intoa totally stubby area to reduce the number
of Type-3 LSAs. Once it is configured, NSSA ABR will inject Type-3 LSAs into the NSSA area for default routes. The
remaining Type-3 LSAs are not allowed inside this area.
Configuration Task List for OSPFv3 (OSPF for IPv6)
This section describes the configuration tasks for Open Shortest Path First version 3 (OSPF for IPv6) on the switch.
The configuration options of OSPFv3 are the same as those options for OSPFv2, but you may configure OSPFv3 with
differently labeled commands. Specify process IDs and areas and include interfaces and addresses in the process. Define areas
as stub or totally stubby.
The interfaces must be in IPv6 Layer-3 mode (assigned an IPv6 IP address) and enabled so that they can send and receive
traffic. The OSPF process must know about these interfaces. To make the OSPF process aware of these interfaces, assign
them to OSPF areas.
The OSPFv3 ipv6 ospf area command enables OSPFv3 on the interface and places the interface in an area. With OSPFv2,
two commands are required to accomplish the same tasks — the router ospf command to create the OSPF process, then
the network area command to enable OSPF on an interface.
NOTE:
The OSPFv2 network area command enables OSPF on multiple interfaces with the single command. Use the
OSPFv3 ipv6 ospf area command on each interface that runs OSPFv3.
All IPv6 addresses on an interface are included in the OSPFv3 process that is created on the interface.
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Open Shortest Path First (OSPFv2 and OSPFv3)