From: mani poopal (mani_ccie@yahoo.com)
Date: Wed Oct 06 2004 - 20:35:52 GMT-3
Brian,
If R1 connect to area 0 & 1. R2 connect to area 1& 2. How can I make an unnumbered interface (R2's lo 0 to participate in area 0). Is the following config should be ok on R2(note I am advertiseing lo 0 of R2 in area 0 eventhough R2 is not connected to area 0.)
Example:
----------area 0---R1(15.1.1.1)------Area 1--------(15.1.1.2)R2-----Area 2------R3
R1 lo 0=10.1.1.1/24
R2 lo 0=10.2.2.2/24
R2 lo 0=10.3.3.3/24
R1 Config:
router ospf 1
network 15.1.1.1 0.0.0.0 area 1
network 10.1.1.1 0.0.0.0 area 0
int tunnel 0
ip unnumbered lo 0
tunnel source 15.1.1.1
tunnel destination 15.1.1.2
R2 Config:
router ospf 1
network 15.1.1.2 0.0.0.0 area 1
network 10.2.2.2 0.0.0.0 area 0<------Since I am using unnumbered lo 0 is it area 0 or 2
int tunnel 0
ip unnumbered lo 0
tunnel source 15.1.1.2
tunnel destination 15.1.1.1
PS:Brian in R2 the loopback is advertised as area 0 or area1. With the above config, will I will be able to see R3's routes(lo 0) in R1. I haven't tested yet. Thanks for taking your time.
Mani
Brian McGahan <bmcgahan@internetworkexpert.com> wrote:
Mani,
As long as the tunnel sources and destinations are reachable by
both endpoints of the tunnel, the ip address used on the tunnel itself
is arbitrary, as long as it participates in area 0. Also, you don't
necessarily even have to give the tunnel it's own address. You could
unnumber it to another interface that is already participating in OSPF
area 0.
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> mani poopal
> Sent: Wednesday, October 06, 2004 1:32 PM
> To: James
> Cc: ccielab@groupstudy.com
> Subject: Re: ospf virtual-links vs GRE
>
> Hi James,
>
> Thanks for the info. From where we are getting ip address for the
tunnel
> interface(10.1.10.1). Then we are advertising this network in the
routing
> domain and this route is propaged to the rest of the network. Is it
ok to
> come up with an ip address for tunnel interface. Because we shouldn't
> learn about the tunnel interface itself from the routing
protocol(ospf),
> do we have to advertise it in a different routing protocol, say rip.
I am
> looking through cisco website and could not get good config example
for
> gre/tunnel interface for ospf/rip/eigrp configuration. Any suggestion
> which books or url is better for this subject. By the way I tried the
> command you gave me and is not working, from both ABR's I created a
tunnel
> interface and advertised both tunnel interface in area 0.
>
> thanks
>
> Mani
>
> James wrote:
> On Wed, Oct 06, 2004 at 06:36:37AM -0700, mani poopal wrote:
> > Hi Group,
> >
> > In the exam if an ospf area is not connected to area 0, you can use
> virtual link to have the connectivity. It the requirement says not to
use
> virtual link, I know you can achieve the desired result by GRE tunnel.
Can
> any one point me to sampe url for configuration in the cisco website
or
> post a sample config.
>
> Router A:
> in tun0
> tun so a.a.a.a
> tun des b.b.b.b
> ip add 10.1.10.1 255.255.255.252
> no shut
> !
> router osp 100
> net 10.1.10.0 0.0.0.3 ar 0
> !
>
> Router B:
> in tun0
> tun so b.b.b.b
> tun des a.a.a.a
> ip add 10.1.10.2 255.255.255.252
> no shut
> !
> router osp 100
> net 10.1.10.0 0.0.0.3 ar 0
> !
>
> HTH,
> -J
>
>
> --
> James Jun TowardEX Technologies, Inc.
> Technical Lead Network Design, Consulting, IT Outsourcing
> james@towardex.com Boston-based Colocation & Bandwidth Services
> cell: 1(978)-394-2867 web: http://www.towardex.com , noc: www.twdx.net
>
>
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