[c-nsp] PFR Question

jack daniels jckdaniels12 at gmail.com
Fri Mar 26 22:20:10 EDT 2010


IN SCENARIO BOTH LINKS FROM SAME SERVICE PROVIDER -But how will this avoid
drops when PE1and CE1 link goes down as MPBGP bring secondary path as best
in BGP table ( MPLS domain )and then to routing table will take atleast 3
min.
Till secondry path not in routing table there will be pcket drops.So PE3
will converge so fast.



On 3/26/10, David Prall <dcp at dcptech.com> wrote:
>
> 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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