Regading NSSA

vinoth.kumar · ‎05-08-2007

Hi,

i need information between stub area(As Default route to reach any destination)and not so stuby area(AS some specfic rute rather than default route).in which circumstances the both stub and NSSA is used

What it identifies the AGE column when viewing the LSA types and in which type it show the AGE as DONT AGE OUT

#show ip ospf database

can u explain the TYPE 6 LSA and what it describe (In books it mentioned as generated by special type of multicast OSPF router)what it means and were it is generated

Regards,

Vinoth

Jon Marshall · ‎05-08-2007

Hi Vinoth

A stub area is one in which only type 1, 2 & 3 LSA's are advertised into that area. Any routes external to the OSPF autonomous system will not be advertised and a default route will advertised into the area instead.

Note that summary network routes external to that OPSF area but still within the OSPF autonomous system will be advertised into the stub area.

For completeness a totally stubby area replaces all external routes whether internal to the autonomous system or external with a default route.

If you have an area where you have an OSPF router that speaks to another router that is not part of the OSPF autonomous system then the OSPF router would become an ASBR. As such this area could not be a stub area. By making an area an NSSA you allow external routes to the autonomous system to be advertised into the AS and still treat this area as a stub area in relation to the rest of the AS.

Not sure i fully understand the question as regards the aging - could you be a bit more specific.

The type 6 LSA is to do with multicast and MOSPF which is a multicast routing protocol which serves the same purpose as the more familiar PIM. MOSPF is not supported by Cisco routers.

HTH

Jon

vinoth.kumar · ‎05-09-2007

Thanks for your reply

When i put a command #show ip ospf database

in a multiarea ospf router

it will show the

ROUTER LINK STATES (TYPE 1 LSA)

router adv roueter age seq no checksum

what it defines of AGE in the column of the LSA types

and i heard some were in ospf that the AGE will not AGE OUT

were that is and why ?

Thanks in Advance

vinoth

bjornarsb · ‎05-08-2007

Hi,

You should have a look at this example:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094a74.shtml

NSSA is applicable when you do not have only one exit point. Lets say a prefix is reached using another link than the one you use for everything else (default gateway)

HTH

Regards,

Bjornarsb