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NSSA ?

Hi,

I have just set up a lab and created a NSSA. I noticed that it doesn't advertise default as is the case with a Stub area. Can someone confirm if this is the correct behaviour for NSSA ? as Doyle doesn't mention it.

Phil.

1 ACCEPTED SOLUTION

Accepted Solutions
Silver

Re: NSSA ?

If you are not receiving a 0/0 in your NSSA area then the following may help. As per RFC3101:

In addition, an NSSA border router should originate a default LSA (IP network is 0.0.0.0/0) into the NSSA. Default routes are necessary because NSSAs do not receive full routing information and must have a default route in order to route to AS-external destinations. Like stub areas, NSSAs may be connected to the Area 0 backbone at more than one NSSA border router, but may not be used as a transit area.

Hope this helps.

2 REPLIES
Silver

Re: NSSA ?

If you configure an area as NSSA only then the NSSA ABR will not generate a default summary route automatically; if you want this capability then you have to configure it explicitly by:

area x nssa default-information originate

Please note that if you configure an area as an NSSA totally-stub area then a default is automatically generated.

Silver

Re: NSSA ?

If you are not receiving a 0/0 in your NSSA area then the following may help. As per RFC3101:

In addition, an NSSA border router should originate a default LSA (IP network is 0.0.0.0/0) into the NSSA. Default routes are necessary because NSSAs do not receive full routing information and must have a default route in order to route to AS-external destinations. Like stub areas, NSSAs may be connected to the Area 0 backbone at more than one NSSA border router, but may not be used as a transit area.

Hope this helps.

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