Re: split horizon

Hi jack,
CE hub won't be doing the advertisement. It will be done by PE1. Don't forget PE1 is also running ospf and has all the routes in bgp. So routes from the other PEs will be tagged with RT 2:2 and exported. This will be imported on the other PEs where the routes from PE2 will be imported by PE3 and vice versa. These routes are then redistributed into ospf for the connected CEs. The CEs will not advertise the routes learnt from the PE back to them and there will be no need to do this.

Kolade
Sent from my BlackBerry. wireless handheld from Glo Mobile.

-----Original Message-----
From: jack daniels <jckdaniels12_at_gmail.com>
Date: Wed, 6 Jan 2010 00:06:14
To: <Charles.Henson_at_regions.com>
Cc: Cisco certification<ccielab_at_groupstudy.com>; Marko Milivojevic<markom_at_ipexpert.com>; <nobody_at_groupstudy.com>
Subject: Re: split horizon

CE (HUB)
G0/1
|
OSPF
|
PE1
|
MPLS CLOUD-----------------------------PE2------OSPF-CE(SPOKE1) (
2.2.2.0/24)

|
|
|
PE3
|
OSPF
|
CE(SPOKE2) (1.1.1.0/24)

IN VRF of customer -

PE3 advertises 1.1.1.0/24 routes with RT1:1 and imports 2:2

PE2 advertises 2.2.2.0/24 routes with RT 1:1 and imports 2:2

PE1 exports routes with RT 2:2 and imports 1:1

NOW 1.1.1.0/24 is learnt on CE HUB Gi0/1 via OSPF .....
Will CE HUB advertise 1.1.1.0/24 on Gi0/1 back as it is required for CE
SPOKE1 for SPOKE to SPOKE reachabilty via HUB?

On Tue, Jan 5, 2010 at 11:57 PM, <Charles.Henson_at_regions.com> wrote:

> Hey Jack,
> How about a little more details? Configs? Shows? Anything? Marko is
> correct.
>
> Charles Henson
>
>
>
>
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> |Marko Milivojevic <markom_at_ipexpert.com>
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> | Cc: |
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> |Cisco certification <ccielab_at_groupstudy.com>
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> |01/05/2010 12:21 PM
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> |Re: split horizon
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> I understand that but ,u mean in OSPF
>
> IF i recive 1.1.1.0/24 on G0/1 of HUB
>
> I'LL advertise 1.1.1.0/24 on Gi0/1 (SAME INTERFACE) of HUB
>
>
>
>
> On Tue, Jan 5, 2010 at 11:44 PM, Marko Milivojevic
> <markom_at_ipexpert.com>wrote:
>
> > On Tue, Jan 5, 2010 at 19:00, jack daniels <jckdaniels12_at_gmail.com>
> > wrote:
> > > Hi guys,
> > >
> > > I have a scenario where in MPLS VPN - HUB and SPOKE.
> > >
> > > CE-PE protocol is OSPF everywhere
> > >
> > >
> > > HUB is recieving routes from one SPOKE on int G0/1 and not advertiseing
> > on
> > > same (SPLIT horizon).
> > >
> > > In ospf how can we overcome such issue.
> >
> > OSPF is a link state protocol. It doesn't use split horizon (at least
> > not within the same area and even in multiarea, the behavior is not
> > called that). You are probably having some other issue...
> >
> > --
> > Marko Milivojevic - CCIE #18427
> > Senior Technical Instructor - IPexpert
> >
> > Mailto: markom_at_ipexpert.com
> > Telephone: +1.810.326.1444
> > Fax: +1.810.454.0130
> > Community: http://www.ipexpert.com/communities
>
>
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>
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Received on Tue Jan 05 2010 - 19:23:35 ART