From: Scott Morris (swm@emanon.com)
Date: Mon Dec 08 2003 - 20:47:05 GMT-3
You're correct that it will always be in the local routers' database as
it appears to be generated from that no-summary command. (go figure)
The nssa default information command (manual) brings the route in as an
N2 external NSSA by default. So if you are told to not have it as an IA
(type 3 LSA) then you will need to use the manual version of bringing it
in.
If you are told to not have one at all, then your options are the
distribute list as you mention, or to not use the "no summary" part of
the command. With the no-summary part, you are killing all type 3, 4
and 5 LSAs from coming into the area. This means without the 0/0 you
will effectively cut that area out of the network.
You just need to look at what things are needed where. NSSA will
disallow any type 4 and type 5 LSAs, and uses type 7 internally
(converted into type 5/type 4 when they hit the backbone). It's not so
much that the ABR "deletes" the LSA, but it decides to not send it out.
That's the kinda hard part.
One has to go back and as "why". :)
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
CISSP, JNCIS, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Adel Abushaev
Sent: Monday, December 08, 2003 6:28 PM
To: ccielab@groupstudy.com
Subject: Re: how to filter out default route in OSPF totally stub area?
Good evening,
Type 3 0.0.0.0 LSA will still be there in ospf database. All the
mechanisms to filter it out will apply between ospf database and
routeing table. In addition to the distance command, "distribute-list
in" can be used under router ospf to filter specific prefixes.
In 12.2(15)T there is a distribute-list with route-map, where you
may specify a route-map of what to put and what to filter.
I will assume this task is "feature-understanding" practice, because
otherwise IA 0.0.0.0 is the only way to get out of totally stubby area
and should better stay there. Also, according to OSPF RFC, the only
router that can delete LSA in area is the router that generated that LSA
in area, which is in case of totally stubby area and IA 0.0.0.0 is an
ABR of a totally stubby area.
Adel Abouchaev
CCIE# 12037, MCSE
http://www.netmasterclass.net
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