Specifications

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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, Release 5.0(3)U2(2)
OL-25782-02
Chapter 3 Configuring OSPFv2
Configuring Advanced OSPFv2
Configuring NSSA
You can configure an NSSA for part of an OSPFv2 domain where limited external traffic is required. See
the “Not-So-Stubby Area” section on page 3-9. You can optionally translate this external traffic to an
AS External (type 5) LSA and flood the OSPFv2 domain with this routing information. An NSSA can
be configured with the following optional parameters:
• No redistribution—Redistributed routes bypass the NSSA and are redistributed to other areas in the
OSPFv2 autonomous system. Use this option when the NSSA ASBR is also an ABR.
• Default information originate—Generates an NSSA External (type 7) LSA for a default route to the
external autonomous system. Use this option on an NSSA ASBR if the ASBR contains the default
route in the routing table. This option can be used on an NSSA ABR whether or not the ABR
contains the default route in the routing table.
• Route map—Filters the external routes so that only those routes that you want are flooded
throughout the NSSA and other areas.
• Translate—Translates NSSA External LSAs to AS External LSAs for areas outside the NSSA. Use
this command on an NSSA ABR to flood the redistributed routes throughout the OSPFv2
autonomous system. You can optionally suppress the forwarding address in these AS External LSAs.
If you choose this option, the forwarding address is set to 0.0.0.0.
• No summary—Blocks all summary routes from flooding the NSSA. Use this option on the NSSA
ABR.
BEFORE YOU BEGIN
Ensure that you have enabled the OSPF feature (see the “Enabling the OSPFv2 Feature” section on
page 3-13).
Ensure that there are no virtual links in the proposed NSSA and that it is not the backbone area.
SUMMARY STEPS
1. configure terminal
2. router ospf instance-tag
3. area area-id nssa [no-redistribution] [default-information-originate [route-map map-name]]
[no-summary] [translate type7 {always | never} [suppress-fa]]
4. (Optional) area area-id default-cost cost
5. (Optional) show ip ospf instance-tag
6. (Optional) copy running-config startup-config
Command Purpose
area area-id stub no-summary
Example:
switch(config-router)# area 20 stub
no-summary
Creates this area as a totally stubby area.