Re: Weird MPLS Label Switching Problem

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
>
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>
> 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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Received on Sun Feb 27 2011 - 01:10:14 ART