[c-nsp] PFR Question
jack daniels
jckdaniels12 at gmail.com
Thu Mar 25 20:50:26 EDT 2010
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
>
>
> > -----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/>
> >
> >
> > > -----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/>
> >
> > >
> > >
> > > > -----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/>
> > >
> > > >
> > > >
> > > >
> > > > > -----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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> > nsp at puck.nether.net
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> > > >
> > > >
> > > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >
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