The MPLS-OPS Archive

["harry" <harry@juniper.net>]

Note that an ABR will not accept sumamries from a non-0 area. So while
this is workable:

			    (ABR)
	r1----area1-------r2-------area2--------r3


This is broken:


			    (ABR)
	r1----area1-------r2-------area2--------r3-------area3-------r4


In the abobe, r3 will discard all sumamry LSAs for area 1 becuause it
expects to receive them from area 0. Likewise, r2 ignores the sumamry
LSAs for area 3.

The whole point of area 0 is to provide a "safe place" for the exchange
of summary LSAs (which are handled as distance vector, and could lead to
loops) in a manner that prevent loop formation.

I believe you can set up the L3 VPN you mention without an area 0, but I
would not reccomended it.


//regards



-----Original Message-----
From: Alok Dube [mailto:alokdube1978@rediffmail.com] 
Sent: Friday, July 25, 2003 8:27 AM
To: mpls-ops@mplsrc.com
Subject: Re: RE: [MPLS-OPS]: OSPF and no area 0


Hi,

Thanks for all your replies....

just clarifying my question was:

what happens if there is no area 0 at all, either in customer VPN 
network or in the MPLS core?

this has nothing to do with label distribution by the way as 
someone else mailed me....

im looking at "rings" for customers and "BGP" to propgate areas 
between "rings"...but there is still no Area 0 for the customer's 
IGP.

for eg:
assume customer VPN site-1 is area 1, site-2 is area 2, site-3 is 
area 3

there is no area 0.

is this possible?

-thanks
Alok




On Fri, 25 Jul 2003 Lars Higham wrote :
>It wrapped - connect it so it's ...bgp-mpls-06.txt
>
>-----Original Message-----
> From: Jerome Law [mailto:Jerome.Law@vanco.co.uk]
>Sent: Friday, July 25, 2003 7:25 PM
>To: 'Strahler, Carsten'; 'Alok Dube'; mpls-ops@mplsrc.com
>Subject: RE: [MPLS-OPS]: OSPF and no area 0
>
>
>
>No suck link.
>
>-----Original Message-----
> From: Strahler, Carsten
>[mailto:Carsten.Strahler@lambdanet.net]
>Sent: 25 July 2003 14:39
>To: 'Alok Dube'; mpls-ops@mplsrc.com
>Subject: AW: [MPLS-OPS]: OSPF and no area 0
>
>Hi Alok,
>
>it is recommend but not necessary to have an area 0.
>
>Have a look at
>http://www.ietf.cnri.reston.va.us/internet-drafts/draft-rosen-vpns-ospf
>-
>bgp-
>mpls-06.txt
>to get an better impression about the problems of OSPF
>in a MPLS-VPN environment.
>
>regards
>
>------------------------------------------------------------
>Carsten Strahler
>
>IP Planning
>
>Lambdanet Communications Deutschland AG (AS 13237) 
>Guenther-Wagner-Allee 13 D-30177 Hannover (Germany)
>
>Phone   +49 (0)511 / 84 88 12 57
>Mobile  +49 (0)173 / 629 1257
>Fax     +49 (0)511 / 84 88 12 59
>mailto:carsten.strahler@lambdanet.net
>
>web: www.lambdanet.net
>-----------------------------------------------------------
>
>
>
>
>
> > -----Ursprungliche Nachricht-----
> > Von: Alok Dube [mailto:alokdube1978@rediffmail.com]
> > Gesendet: Freitag, 25. Juli 2003 09:15
> > An: mpls-ops@mplsrc.com
> > Betreff: [MPLS-OPS]: OSPF and no area 0
> >
> >
> > Hi,
> >
> >
> > a. There is an MPLS VPN network.
> >
> > b. The customers may wish to run IGP as OSPF
> >
> > c. The typical problem in such a scenario is the "Area 0" will
>be
> > the "spoke" of the customer's network.? It is my
>understanding
> > that everything would go to Area 0 and then to other areas,
>is
> > this correct?
> >
> > d. Would it be possible to not have an "area0" in the whole
>VPN
> > for the customer? but stillhave individual areas in OSPF?
> >
> > e. my knowledge of ISIS is less,but i assume area0 <->level 2
>in
> > ISIS. Is it possible to have a topology with no level 2 but
>only
> > level  -1 areas/rings for the customers?
> >
> > the information across the OSPF/ISIS Areas on different parts
>of
> > the VPN would be carried by MPBGP.
> >
> > Is this how it is currently done? or do we still have an
>area
> > 0/level-2 area?
> >
> > would appreciate some clarification..
> > -thanks
> > Alok
> >
> >
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