Re: Weird MPLS Label Switching Problem

Hi,

Thanks for all the responses

I am not using propagate-ttl thing anymore and I am getting 4-5 hops between
the CE-CE trace but without any label as if SP core is not running MPLS

I will try with another IOS and will get back to you

Regards,
Malik

On Sun, Feb 27, 2011 at 2:39 PM, eseosa <eseosa.ehiwe_at_gmail.com> wrote:

> Hi Malik
>
> did you use the no mpls ip propagate-ttl command with the forwarded
> keyword ?? ,
>
> if you did then the behaviour you are experiencing is normal as
> traceroutes from CE1 to CE2 will not show the hops in the SP core so
> it appears to the customer as if they are having a single hop or
> better perfromance :) , BUT traceroutes from the PE will shows the
> transit P devices as the command with the forwarded keyword only
> affects forwarded packets(CE TO CE) not locally generated ones.
>
> Else the next step is to consider the IOS version are you using as
> Marko pointed out
>
> On 2/27/11, Marko Milivojevic <markom_at_ipexpert.com> wrote:
> > Which IOS are you using?
> >
> > --
> > Marko Milivojevic - CCIE #18427
> > Senior Technical Instructor - IPexpert
> >
> > FREE CCIE training: http://bit.ly/vLecture
> >
> > Mailto: markom_at_ipexpert.com
> > Telephone: +1.810.326.1444
> > Web: http://www.ipexpert.com/
> >
> > On Sat, Feb 26, 2011 at 22:10, Malik Nouman Ahmad <djmalik_at_gmail.com>
> wrote:
> >
> >> What I was trying to tell that the labels are not shown at all with or
> >> without "no mpls ip propagate-ttl" command. I know this command is to
> hide
> >> all the hops between PE1 and PE2.
> >>
> >> When I was not using that command it was showing the hops from
> >> CE1->PE1->P1->P2->PE1->CE2 BUT without labels like normal IPv4
> traceroute.
> >> I
> >> used that command just to check if MPLS was working or not, just to be
> >> sure
> >>
> >> The problem is that I cannot see the labels for CE1 to CE2 traceroute at
> >> any hop but when I use the same source/destination subnet for tracing
> from
> >> PE1 to PE2 I am able to see label swapping at each hop
> >>
> >> I hope I am able to describe the problem that I am facing
> >>
> >> Thanks,
> >> Malik
> >>
> >>
> >> On Sun, Feb 27, 2011 at 12:29 AM, Marko Milivojevic
> >> <markom_at_ipexpert.com>wrote:
> >>
> >>>
> >>> Which shows you that your "no mpls ip propagate-ttl" did its job and
> MPLS
> >>> backbone is "hidden" from CE devices. Remove this command from PE1, run
> a
> >>> traceroute from CE1 and see the labels re-appear.
> >>>
> >>> --
> >>> Marko Milivojevic - CCIE #18427
> >>> Senior Technical Instructor - IPexpert
> >>>
> >>> FREE CCIE training: http://bit.ly/vLecture
> >>>
> >>> Mailto: markom_at_ipexpert.com
> >>> Telephone: +1.810.326.1444
> >>> Web: http://www.ipexpert.com/
> >>>
> >>> On Sat, Feb 26, 2011 at 21:10, Malik Nouman Ahmad
> >>> <djmalik_at_gmail.com>wrote:
> >>>
> >>>> One thing I forgot to mention. For CE-CE trace there is no label seen
> in
> >>>> the
> >>>> traceroute but trace completes properly and I can ping between the CEs
> >>>> normally
> >>>>
> >>>> Thanks
> >>>>
> >>>> On Sun, Feb 27, 2011 at 12:07 AM, Malik Nouman Ahmad <
> djmalik_at_gmail.com
> >>>> >wrote:
> >>>>
> >>>> > Hi,
> >>>> >
> >>>> > I was studying MPLS VPN and while working on an example I am facing
> >>>> some
> >>>> > strange issue
> >>>> >
> >>>> > The connectivity is CE1 - PE1 - P1 - P2 - PE2 - CE2
> >>>> >
> >>>> > PE1(.1) - CE1 (.2) with subnet 172.16.1.0/24 with VRF A (RD=RT=1:1)
> >>>> > PE2(.1) - CE2 (.2) with subnet 172.16.2.0/24 with VRF A (RD=RT=1:1)
> >>>> >
> >>>> > PE1 & PE2 have MPLS VPN set up and I can see labels for everything
> >>>> > when
> >>>> I
> >>>> > check "show mpls forwarding" on the PEs
> >>>> >
> >>>> > when I trace from PE1 to CE2 I can see labels being switches
> properly
> >>>> using
> >>>> > the following command
> >>>> > trace vrf A 172.16.2.2 source 172.16.1.1
> >>>> >
> >>>> > but when trace from CE1 to CE2, there are no labels whatsoever
> >>>> > trace 172.16.2.2 source 172.16.1.2
> >>>> >
> >>>> > Same thing is happening in the reverse direction (i.e. trace from
> CE2
> >>>> to
> >>>> > CE1). I have done several examples previously and never faced such
> >>>> issue.
> >>>> > Instead of doing it all over again I want to troubleshoot the
> problem
> >>>> for
> >>>> > learning purpose
> >>>> >
> >>>> > Can anybody suggest how to troubleshoot this problem? I have applied
> >>>> "no
> >>>> > mpls ip propagate-ttl" just to see if it was working and it worked
> >>>> >
> >>>> > Please advise what should I do?
> >>>> >
> >>>> > Thanks,
> >>>> > Malik
> >>>>
> >>>>
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>
>
> --
> Warm Regards,
>
> Eseosa
> CCIE #23782
> You can learn anything just develop the right quantity of interest.

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Received on Sun Feb 27 2011 - 17:29:28 ART