[c-nsp] PFR Question
David Prall
dcp at dcptech.com
Thu Mar 25 21:17:16 EDT 2010
This is where PfR is involved to route around the primary carrier to the
secondary.
--
http://dcp.dcptech.com
> -----Original Message-----
> From: jack daniels [mailto:jckdaniels12 at gmail.com]
> Sent: Thursday, March 25, 2010 8:50 PM
> To: David Prall
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] PFR Question
>
> Hi David,
>
> In a multipath instance PE1 will install the Equal Cost route with rd
> 1:1
> first, using 1:2 as a secondary path only. Opposite on PE2.???
> whne both paths have equal cost the why route with rd1:1 will be
> primary always
> and rd 1:2 will be secondary on PE1.
>
> EVEN IF WE advertise X.X.X.X from PE1 and PE2 still PE3 will have two
> routes in BGP table . But one in routing table.
> But how will this avoid drops when PE1and CE1 link goes down as BGP
> bring secondary path to Primary and then to routing table will take
> atleast 3 min.
>
> Regards
>
>
>
> On Fri, Mar 26, 2010 at 12:29 AM, David Prall <dcp at dcptech.com> wrote:
>
>
> 1)
> On PE1
> vrf description customer
> rd 1:1
> route-target both 1:1
> route-target import 1:2
> On PE2
> vrf description customer
> rd 1:2
> route-target both 1:2
> route-target import 1:1
>
> In a multipath instance PE1 will install the Equal Cost route
> with rd 1:1
> first, using 1:2 as a secondary path only. Opposite on PE2.
>
> 2)
> Could use different VRF's. Just like dual carriers. A key concern
> is a dual
> failure, site 1 on network 1 and site 2 on network 2. The
> customer will need
> to provide a path between the two networks via one of their
> sites.
>
>
> David
>
> --
> http://dcp.dcptech.com <http://dcp.dcptech.com/>
>
>
> > -----Original Message-----
> > From: jack daniels [mailto:jckdaniels12 at gmail.com]
>
> > Sent: Thursday, March 25, 2010 2:41 PM
> > To: David Prall
> > Cc: cisco-nsp at puck.nether.net
> > Subject: Re: [c-nsp] PFR Question
> >
>
> > Hi David ,
> >
> > thanks man I got the basic idea :)
> >
> > 1) but please explain in more detail this
> >
> > 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.??????
> >
> >
> > 2) Also if I use diffrent VRF for CE4---CE2 path that will also
> work -
> > ??
> >
> >
> > On Thu, Mar 25, 2010 at 11:57 PM, David Prall <dcp at dcptech.com>
> wrote:
> >
> >
> > 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 <http://dcp.dcptech.com/>
> <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/>
> <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/>
> > <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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