Re: split horizon

Bryan,

it can look something like this.

on Hub,
1. add a static 1.1.1.0/23 to null0
2. redis this into OSPF on hub
3. this will reach spoke1 via Hub-PE-CE ospf and then MPBGP and then
Spoke1-PE-CE OSPF.... Spoke2 can be specially filtered as it doesnt need
this blackhole route.

Swap
#19084

On Wed, Jan 6, 2010 at 1:58 AM, Bryan Bartik <bbartik_at_ipexpert.com> wrote:

> Mirco,
>
> I have not seen that example before. Can you post an example of the Hub CE
> config?
>
> On Tue, Jan 5, 2010 at 2:51 PM, Mirco Orlandi <mirco.orlandi_at_gmail.com
> >wrote:
>
> > Bryan,
> > double link solution work well, without additional prefix advertising.
> >
> > ...but still work with a single link and additional blackhole route
> > advertising at hub ce. Then we can mantain control of spoke2spoke traffic
> > with acl on hub ce wan interface.
> >
> > In double link scenario we have two link used in unidirectional way for
> > spoke2spoke traffic; in single link scenario, one link used in
> bidirectional
> > way.
> > I think this is more common hub&spoke scenario. Do you agree?
> >
> > Regards,
> > mirco.
> >
> >
> > On Tue, Jan 5, 2010 at 9:17 PM, Bryan Bartik <bbartik_at_ipexpert.com>
> wrote:
> >
> >> Hub and Spoke VPNs usually require two links between the hub CE and PE.
> >> Each
> >> link is in a separate VRF on the PE side. The first VRF imports all the
> >> spoke routes and advertise them to the hub CE. The second VRF will take
> >> these routes from the CE and advertise them back to the spokes with a
> >> different RT. The spoke sites will then import this second RT (not the
> >> first). This pulls all traffic from the spokes to the Hub CE and back
> out.
> >>
> >> Remember the goal is to not only get traffic to the Hub PE, but the Hub
> >> CE...which is the tricky part. It has nothing to do with split horizon,
> >> but
> >> rather the way a router builds the shortest path tree. A shortest path
> >> will
> >> never include the same link in two directions without some funky
> >> engineering.
> >>
> >> If you have only have one link between PE and CE, I believe this is not
> a
> >> true hub and spoke and the problem is you are not importing the spoke
> RTs
> >> and at each of the other spokes, only the hub.
> >>
> >> On Tue, Jan 5, 2010 at 1:01 PM, <olukolade_at_gmail.com> wrote:
> >>
> >> > Ignore pls. Been drinking.
> >> > Sent from my BlackBerry. wireless handheld from Glo Mobile.
> >> >
> >> > -----Original Message-----
> >> > From: olukolade_at_gmail.com
> >> > Date: Tue, 5 Jan 2010 19:23:35
> >> > To: jack daniels<jckdaniels12_at_gmail.com>; <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
> >> >
> >> > 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
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > |------------>
> >> > > | From: |
> >> > > |------------>
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |jack daniels <jckdaniels12_at_gmail.com>
> >> > >
> >> > |
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |------------>
> >> > > | To: |
> >> > > |------------>
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |Marko Milivojevic <markom_at_ipexpert.com>
> >> > >
> >> > |
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |------------>
> >> > > | Cc: |
> >> > > |------------>
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |Cisco certification <ccielab_at_groupstudy.com>
> >> > >
> >> > |
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |------------>
> >> > > | Date: |
> >> > > |------------>
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |01/05/2010 12:21 PM
> >> > >
> >> |
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |------------>
> >> > > | Subject: |
> >> > > |------------>
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > > |Re: split horizon
> >> > >
> >> |
> >> > >
> >> > >
> >> >
> >>
> >--------------------------------------------------------------------------------------------------------------------------------------------------|
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > 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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> >> >
> >>
> >>
> >> --
> >> Bryan Bartik
> >> CCIE #23707 (R&S, SP), CCNP
> >> Sr. Support Engineer - IPexpert, Inc.
> >> URL: http://www.IPexpert.com
> >>
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> >>
> >>
> >>
> >>
> >
>
>
> --
> Bryan Bartik
> CCIE #23707 (R&S, SP), CCNP
> Sr. Support Engineer - IPexpert, Inc.
> URL: http://www.IPexpert.com
>
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Received on Wed Jan 06 2010 - 02:17:16 ART