From: diptish doshi (diptishdoshi007@yahoo.com)
Date: Mon Feb 21 2005 - 01:35:07 GMT-3
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 <Paresh.Khatri@aapt.com.au> 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 <vrfname>) 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 <Paresh.Khatri@aapt.com.au> 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.
> >
> > 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"
> >
> > ---------------------------------
> > Do you Yahoo!?
> > Yahoo! Search presents - Jib Jab's 'Second Term'
> >
> >
>
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