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 VOSS OSPF Totally NSSA

Fijs's profile image
Fijs posted 07-02-2020 12:28

Hi,

 

Does VOSS support totally NSSA’s?

I have managed to configure stub area’s, totally stubby area’s, but I don’t see any option to create a totally nssa.

 

What I want to achieve: having totally stubby area (only a default route towards area 0), but other routers in that area should be able to redistribute static routes back into area 0.

 

Thanks!

Paul A. Leroux's profile image
Paul A. Leroux
Fijs's profile image
Fijs

Hi Paul,

 

Thanks for the link. I ideed used this guide to successfully configure stub, totally stub, and nssa areas.

However it does not cover “totally nssa” / “NSSA Totally Stub Area”.

 

A “totally nssa” area should advertise only a default route from the ABR. The difference with a “totally stubby area”, is that a “totally nssa” can have ASBR’s in it.

So I guess I should configure the area as NSSA, and set “no area X.X.X.X import-summaries enable”; but this is not possible:

VSP:1(config-ospf)#area 1.0.0.0 import nssa
VSP:1(config-ospf)#no area 1.0.0.0 import-summaries enable
Error: cannot set import summary to be false if not stub area

 

Also,

area X.X.X.X stub

and

are X.X.X.X import nssa

seems to be mutually exclusive:

### NSSA ###
VSP:1(config-ospf)#area 1.0.0.0 import nssa
VSP:1(config-ospf)#sho ip ospf area


====================================================================================================
OSPF Area - GlobalRouter
====================================================================================================
AREA_ID STUB_AREA NSSA IMPORT_SUM ACTIVE_IFCNT
----------------------------------------------------------------------------------------------------
0.0.0.0 false false true 0
1.0.0.0 false true true 0

STUB_COST INTRA_AREA_SPF_RUNS BDR_RTR_CNT ASBDR_RTR_CNT LSA_CNT LSACK_SUM
----------------------------------------------------------------------------------------------------
0 0 0 0 0 0
1 0 0 0 0 0

### Changing to Stub ###
VSP:1(config-ospf)#area 1.0.0.0 stub
VSP:1(config-ospf)#sho ip ospf area


====================================================================================================
OSPF Area - GlobalRouter
====================================================================================================
AREA_ID STUB_AREA NSSA IMPORT_SUM ACTIVE_IFCNT
----------------------------------------------------------------------------------------------------
0.0.0.0 false false true 0
1.0.0.0 true false true 0

STUB_COST INTRA_AREA_SPF_RUNS BDR_RTR_CNT ASBDR_RTR_CNT LSA_CNT LSACK_SUM
----------------------------------------------------------------------------------------------------
0 0 0 0 0 0
1 0 0 0 0 0

 

RobertD's profile image
RobertD
Hi,

How do you disable Import-Summaries for NSSA, it seems can only be done for area stub?

It does appear not to send other LSA types 5, 4 and 3 into the area, only a default route is seen via NSSA LSA (and any local routes of course). 

It is just not clear then what the difference is between NSSA and Totally NSSA I suppose. No default-information-originate option. 

If all routers in NSSA need to be configured as NSSA how does it know which one to originate the default route from?

Rob