From: Swaroop Potdar (swarooppotdar@hotmail.com)
Date: Wed Feb 23 2005 - 10:53:42 GMT-3
Hi Andre,
Could you kindly clarify whether you are finding problems in doing the load
balancing or what is it?
if possible you can paste your configuration describing the problem you are
facing.
Hi Diptish,
What I feel Paresh was saying is 2 CE's located at different locations and
also a part of the same VPN
can always have a backhaul non-MPLS link between the networks.
In that case the same network would be advertised by both the CE's into the
MPLS domain.
HTH,
Swaroop Potdar
DataCraft Asia.
>From: "Paresh Khatri" <Paresh.Khatri@aapt.com.au>
>Reply-To: "Paresh Khatri" <Paresh.Khatri@aapt.com.au>
>To: "Andre Scalco" <a_scalco@yahoo.com>, ccielab@groupstudy.com
>Subject: RE: MPLS MP-BGP router behavior
>Date: Tue, 22 Feb 2005 10:30:09 +1100
>
>Andre,
>
>To clarify things somewhat, would you be able to include a bit more detail.
>Specifically:
>- the RDs used on PE1, PE2, PE3
>- the import/export route-targets on PE1, PE2, PE3
>
>Cheers,
>Paresh.
>
>-----Original Message-----
>From: Andre Scalco [mailto:a_scalco@yahoo.com]
>Sent: Tuesday, 22 February 2005 06:46 AM
>To: Paresh Khatri; diptish doshi; ccielab@groupstudy.com
>Subject: RE: MPLS MP-BGP router behavior
>
>
>
>
>
>
>See link below from Cisco
>
>http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t
>/122t4/fteibmpl.htm#1027129
>
>Strange thing is I have different RD's so in terms of MPLS the announcement
>from PE2 and PE3 are different so PE1 should have both.
>
>Let me know what you guys think
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>eBGP and iBGP Multipath Load Sharing With Route Reflectors
>
>
>Figure
><http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122
>t/122t4/fteibmpl.htm#92520> 2 shows a topology that contains three PE
>routers
>and a route reflector, all configured for iBGP peering. PE router 2 and PE
>router 3 each advertise an equal preference eBGP path to PE router 1. By
>default, the route reflector will choose only one path and advertise PE
>router
>1.
>
>
>Figure 2 A Topology With a Route Reflector
> <http://www.cisco.com/univercd/illus/6/37/60937.gif>
>
>For all equal preference paths to PE router 1 to be advertised through the
>route reflector, you must configure each VRF with a different RD. The
>prefixes
>received by the route reflector will be recognized differently and
>advertised
>to PE router 1.
>
>
>
>Paresh Khatri <Paresh.Khatri@aapt.com.au> wrote:
>
>Hi,
>
>I don't see any reason why it would not work. It's perfectly ok for two CEs
>advertising the same route to be in the same MPLS VPN.
>
>I'm afraid I don't quite understand what you are getting at ? Could you
>expand
>on what you think will not work ?
>
>Cheers,
>Paresh.
>
>-----Original Message-----
>From: diptish doshi [mailto:diptishdoshi007@yahoo.com]
>Sent: Monday, 21 February 2005 02:35 PM
>To: Paresh Khatri; ccielab@groupstudy.com
>Subject: RE: MPLS MP-BGP router behavior
>
>
>yeah right ,
>
>thats what i mean .. .that the present sceniario
>wont work ... unless both the CE advertising 10.0.0.0
>are in different MPLS VPN . am i right .. whats ur
>opinion ?
>
>Thanx.
>Diptish .
>
>
>--- Paresh Khatri wrote:
>
> > Hi,
> >
> > I think you mis-understood what I meant.. The
> > routing table on PE1 will not have two routes in it
> > but the BGP table (the output of show ip bgp vpnv4
> > vrf ) will have two paths shown in it, of
> > which the path learned from PE2 will be marked with
> > a ">" sign, indicating that is the best route. This
> > route will then be installed in the IP routing table
> > on that router.
> >
> > Paresh
> >
> > -----Original Message-----
> > From: diptish doshi
> > [mailto:diptishdoshi007@yahoo.com]
> > Sent: Monday, 21 February 2005 02:19 PM
> > To: Paresh Khatri; ccielab@groupstudy.com
> > Subject: RE: MPLS MP-BGP router behavior
> >
> >
> > hi there ,
> >
> > I really doubt about the actual routing taking
> > place ... i mean in the routing table ... 2 paths
> > will
> > be shown for the same destination ( 10.0.0.0/24 )
> > but
> > how do u think it would be possible to reach both
> > the
> > CE ( CE advertising 10.0.0.0 ) from any PE in the
> > network at a same time ?? IT WOULD BE ONLY POSSIBLE
> > IF BOTH ARE IN DIFFERENT MPLS-VPN .
> > Please also do let me know if any other
> > possiblities
> > .
> >
> > Thanx and regards,
> > Diptish .
> >
> > --- Paresh Khatri wrote:
> >
> > > Hi Andre,
> > >
> > > Let's call the PE setting the LP to 100 - PE1
> > > Let's call the PE setting the LP to 150 - PE2
> > > The third PE is, of course, PE3.
> > >
> > > I assume there is a full MP-BGP mesh between the 3
> > > PEs.
> > >
> > > When PE1 receives the BGP route from PE2, it will
> > > select that route as the best path. Therefore, if
> > > it has previously advertised the route that it
> > > learnt from the CE (with a LP of 100), it will
> > > withdraw that route. Since this is IBGP, it will
> > > not be advertising any route for that network at
> > all
> > > now, to the other PEs. This behaviour stems from
> > > the fact that a BGP peer only advertises what it
> > > considers to be the "best" path. For PE1, the
> > best
> > > route is through PE2, so it does not advertise
> > it's
> > > locally learnt route. The only PE on which you
> > > should see both routes is PE1.
> > >
> > > HTH,
> > > Paresh.
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com
> > > [mailto:nobody@groupstudy.com]On Behalf Of
> > > Andre Scalco
> > > Sent: Saturday, 19 February 2005 02:00 PM
> > > To: ccielab@groupstudy.com
> > > Subject: MPLS MP-BGP router behavior
> > >
> > >
> > > I'm testing some features of MPLS in a LAB and I
> > got
> > > a scenario that I would like to discuss with you.
> > >
> > > I have two CEs configured injecting the same
> > network
> > > (10.0.0.0/24) to their respective PEs, one PE is
> > > setting the Local Preference as 100 and the other
> > > one as 150.
> > >
> > > On a Third PE I do see the network 10.0.0.0/24
> > being
> > > correctly learned from the PE that is setting the
> > LP
> > > as 150, but I don't actually see on my bgp table
> > for
> > > that VRF the other possible path from the PE
> > that's
> > > setting as 100.
> > >
> > > My assumption is that when the Third PE do the
> > > "scan" to place that 10.0.0.0/24 under the VRF it
> > > does select only one possible path regardless the
> > > network is coming from more than one place.
> > However
> > > if I do a "Show ip bgp vpn rd all" then I should
> > see
> > > this network from the two PEs that are advertising
> > > this network.
>& gt; >
> > > So in other words, in MP-BGP I should consider
> > this
> > > rules with extended community RT before any
> > standard
> > > best path selection algorithm "weight,lp,med,etc"
> > >
> > > Let me know what you guys think,
> > >
> > > Andre
> > >
> > >
> > > Best Regards,
> > >
> > > Andre Scalco
> > > "Think Outside the Bun"
> > >
> > > ---------------------------------
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>Best Regards,
>
>Andre Scalco
>"Think Outside the Bun"
>
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Regards,
Swaroop.
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