From: Scott Morris (swm@emanon.com)
Date: Fri Nov 10 2006 - 22:18:18 ART
I suppose it would depend on the extent of your configuration. Look at the
explanation of "no-redistribute" for NSSA areas:
"(Optional) Used when the router is an NSSA Area Border Router (ABR) and you
want the redistribute command to import routes only into the normal areas,
but not into the NSSA area."
So that's only on a router that functions both as an ABR and an ASBR. That
(IMHO) would be more a corner case. Personally, the way I look at is is
that if you want a stub area type, use a stub area. NSSA should be the last
resort, and specifically when you DO need to redistribute.
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
IPExpert VP - Curriculum Development
IPExpert Sr. Technical Instructor
smorris@ipexpert.com
http://www.ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Michael Zuo
Sent: Friday, November 10, 2006 7:23 PM
To: Ian Blaney; Angelo De Guzman; Adhu Ajit
Cc: ccielab@groupstudy.com
Subject: RE: difference between two OSPF area types
Hi Guys, thanks for the replies.
Unfortunately, I am getting more confused :-) sorry about being so slow.
If I configure "area 1 stub no-summary", the area will only have type 1,
2 LSA plus one type 3 default route
If I configure "area 1 nssa no-summary no-redistribution", "no-summary"
will block out type 3 LSA except one default route. "no-redistribution"
will block out type 7 LSA. What is left is type 1, 2 and one type 3 default
route.
As this point two command will yield the same types of LSAs, wouldn't they
be equivalent?
thanks
________________________________
From: Ian Blaney [mailto:ian.blaney@gmail.com]
Sent: Friday, November 10, 2006 1:22 AM
To: Michael Zuo
Cc: ccielab@groupstudy.com
Subject: Re: difference between two OSPF area types
Michael
When an ABR is also an ASBR and is connected to a NSSA the default behavior
is to send redistributed routes into the NSSA.
With the no-redistribution option redistribution will be turned off on the
ABR/ASBR into the NSSA. The no-summary will send a type 3 default route into
the NSSA and block the flooding of type 3 and type 4 LSAs into the NSSA
I hope the diagram below is readable. R1 is an ABR for the OSPF NSSA area
and also an ASBR for the redistributed RIP routes from R2. The
no-redistribution option will prevent the redistributed RIP routes being
advertised into the OSPF NSSA area.
OSPF
R1 NSSA R3
RIP
R2
Ian
On 11/10/06, Michael Zuo <mzuo@ixiacom.com> wrote:
Hi Group,
Anyone knows the difference between:
Area 1 nssa no-summary no-redistribution
And
Area 1 stub no-summary
To me, they seem to be the same thing...
thanks
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