[c-nsp] PFR Question

[David Prall]

If the link goes away, then the update should be pretty quick. 

Single VRF, 2 distinct RD's. The VRF imports both, exports one. The RD's are
different so that multipath can be used within the core typically. But in
this case they wouldn't use multipath and the local RD would be used as the
determining factor on import of which route is installed first. 

The local CE (CE3) is probing for the subnet at CE1. When it is no longer
reachable by CE3 it will move the route to CE4. As long as CE4 is using CE2
as the path via the cloud then no issue.

David

--
http://dcp.dcptech.com


> -----Original Message-----
> From: jack daniels [mailto:jckdaniels12 at gmail.com]
> Sent: Thursday, March 25, 2010 2:19 PM
> To: David Prall
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] PFR Question
> 
> If a single carrier, then the CE4/CE2 path needs to be via
> a second RD so that the paths within the carrier are preferred and the
> same
> will happen.????
> DO YOU mean we need to have diifrent vrf on secondry end to end path.
> 
> I didnt get this if single carrier as link PE1 and CE1 link fails
> ....CE3 send traffic for X.X.X.X to PE3.PE3 still has next hop in its
> vrf table as PE1....
> 
> 
> 
> 
> Please help me as still confused if two carriers , how will this
> hhappen
> 
> 
> On Thu, Mar 25, 2010 at 11:29 PM, David Prall <dcp at dcptech.com> wrote:
> 
> 
> 	Is MPLS Domain a single carrier, or two carriers. If two carriers
> then the
> 	CE3/CE4 site will see that they can't reach via CE3/CE1 path and
> switch over
> 	to CE4/CE2 path. If a single carrier, then the CE4/CE2 path needs
> to be via
> 	a second RD so that the paths within the carrier are preferred
> and the same
> 	will happen. PfR is providing end-to-end reachability information
> in this
> 	case, and based on that changing the local routing table.
> 
> 	David
> 
> 
> 	--
> 	http://dcp.dcptech.com <http://dcp.dcptech.com/>
> 
> 
> 	> -----Original Message-----
> 
> 	> From: jack daniels [mailto:jckdaniels12 at gmail.com]
> 	> Sent: Thursday, March 25, 2010 1:07 PM
> 	> To: David Prall
> 	> Cc: cisco-nsp at puck.nether.net
> 	> Subject: Re: [c-nsp] PFR Question
> 	>
> 
> 	> But if you have --
> 	>
> 	>
> 	>                       |CE1--------PE1
> 	> PE3--------CE3
> 	>  X.X.X.X---------|                 --------------------MPLS
> DOMAIN-----
> 	> --------------
> 	>                      |  CE2--------PE2
> 	> PE4--------CE4
> 	>
> 	>
> 	> Now my primary link is CE1-PE1 and secondary is CE2-PE2
> 	> If my CE1-PE1 goes down i route traffic via CE2-PE2<<<<<<I
> understand
> 	> this ok...
> 	>
> 	> when traffic from CE3 for X.X.X.X reaches PE3 , next hop is
> still PE1 (
> 	> as MPBGP has not converged so fast in MPLS domain of SP) ...so
> how will
> 	> traffic be forwareded , as PFR claims 3 sec.
> 	>
> 	>
> 	> On Thu, Mar 25, 2010 at 10:16 PM, David Prall <dcp at dcptech.com>
> wrote:
> 	>
> 	>
> 	>       PfR is a unidirectional feature. The router on the other
> end
> 	> needs to be
> 	>       configured with PfR as well in order to have
> bidirectional
> 	> visibility.
> 	>       Typically the master controller will be local to the
> site.
> 	>
> 	>       --
> 
> 	>       http://dcp.dcptech.com <http://dcp.dcptech.com/>
> <http://dcp.dcptech.com/>
> 
> 	>
> 	>
> 	>
> 	>       > -----Original Message-----
> 	>       > From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-
> nsp-
> 	>       > bounces at puck.nether.net] On Behalf Of jack daniels
> 	>       > Sent: Thursday, March 25, 2010 12:35 PM
> 	>       > To: cisco-nsp at puck.nether.net
> 	>       > Subject: Re: [c-nsp] PFR Question
> 	>       >
> 	>       > dear guys,
> 	>       >
> 	>       > is my mail being delivered to group as no one replied.
> 	>       >
> 	>       > On Wed, Mar 24, 2010 at 11:42 PM, jack daniels
> 	>       > <jckdaniels12 at gmail.com>wrote:
> 	>       >
> 	>       > > Hi Network champs,
> 	>       > >
> 	>       > > I'm stuck in understanding of PFR . Docs say it
> converges in
> 	> 3 sec (
> 	>       > for
> 	>       > > realtime traffic VOICE )...
> 	>       > >
> 	>       > > I understand you can send traffic out secondry link
> but what
> 	> about
> 	>       > traffic
> 	>       > > which has to come back from remote end ( for which SP
> has not
> 	>       > converged).
> 	>       > >
> 	>       > > But if you have --
> 	>       > >
> 	>       > >
> 	>       > >
> 	>       > > |CE1--------PE1
> 	>       > > PE3--------CE3
> 	>       > >  X.X.X.X---------|                 ------------------
> --MPLS
> 	>       > > DOMAIN-------------------
> 	>       > >                      |  CE2--------PE2
> 	>       > > PE4--------CE4
> 	>       > >
> 	>       > >
> 	>       > > Now my primary link is CE1-PE1 and secondary is CE2-
> PE2
> 	>       > > If my CE1-PE1 goes down i route traffic via CE2-
> PE2<<<<<<I
> 	> understand
> 	>       > this
> 	>       > > ok...
> 	>       > >
> 	>       > >
> 	>       > > BUT MY QUESTION IS -
> 	>       > >
> 	>       > > PE3 and PE4 ( for this VRF) still has NOW converged
> the BGP
> 	> and still
> 	>       > for
> 	>       > > it next hop for X.X.X.X is PE1. So how fwd can happen
> in 3
> 	> sec untill
> 	>       > > Service providers all routers dont converge and
> understand
> 	> that CE1-
> 	>       > PE1 link
> 	>       > > is down.
> 	>       > >
> 	>       > >
> 	>       > > Regards
> 	>       > >
> 	>       > >
> 	>
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> 
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