Mailing List Archive: Cisco: NSP

debug mpls packet

Index | Next | Previous | View Threaded

andy.saykao at staff

Nov 16, 2009, 11:03 PM

Post #1 of 10 (815 views)
Permalink

debug mpls packet

Hi All,

Does anyone know what the middle number represents in a "debug mpls
packet" ( eg: {7963 6 254} )?
I can't find this information anywhere.

router#debug mpls packet gigabitEthernet 0/2
Packet debugging is on on idb GigabitEthernet0/2
router#
Nov 17 16:26:07.670 AEDT: MPLS turbo: Gi0/2: rx: Len 97 Stack {7963 6
254} - ipv4 data
Nov 17 16:26:08.442 AEDT: MPLS turbo: Gi0/2: rx: Len 78 Stack {7963 6
254} - ipv4 data
Nov 17 16:26:11.882 AEDT: MPLS turbo: Gi0/2: rx: Len 82 Stack {18 0 254}
{2750 0 255} - ipv4 data
Nov 17 16:26:11.882 AEDT: MPLS turbo: Gi0/1: tx: Len 82 Stack {8878 0
253} {2750 0 255} - ipv4 data

{7963 6 254}

7693 = Label
6 = ???
254 = I presume is the TTL

What does the 6 represent??

In the other label, it's a ZERO instead {18 0 254} .

Thanks.

Andy

This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
Please notify the sender immediately by email if you have received this
email by mistake and delete this email from your system. Please note that
any views or opinions presented in this email are solely those of the
author and do not necessarily represent those of the organisation.
Finally, the recipient should check this email and any attachments for
the presence of viruses. The organisation accepts no liability for any
damage caused by any virus transmitted by this email.

_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

oboehmer at cisco

Nov 16, 2009, 11:25 PM

Post #2 of 10 (788 views)
Permalink

Re: debug mpls packet [In reply to]

>
> Does anyone know what the middle number represents in a "debug mpls
> packet" ( eg: {7963 6 254} )?
> I can't find this information anywhere.
>
> 7693 = Label
> 6 = ???
> 254 = I presume is the TTL
>
> What does the 6 represent??

it's the EXP value. you're right about the last being the TTL.

oli
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

bandwidth.user at gmail

Nov 16, 2009, 11:43 PM

Post #3 of 10 (787 views)
Permalink

Re: debug mpls packet [In reply to]

Oliver Boehmer (oboehmer) wrote:
>> Does anyone know what the middle number represents in a "debug mpls
>> packet" ( eg: {7963 6 254} )?
>> I can't find this information anywhere.
>>
>> 7693 = Label
>> 6 = ???
>> 254 = I presume is the TTL
>>
>> What does the 6 represent??
>
> it's the EXP value. you're right about the last being the TTL.
>
> oli

Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?

Roy
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

oboehmer at cisco

Nov 16, 2009, 11:49 PM

Post #4 of 10 (787 views)
Permalink

Re: debug mpls packet [In reply to]

> >> Does anyone know what the middle number represents in a "debug mpls
> >> packet" ( eg: {7963 6 254} )?
> >> I can't find this information anywhere.
> >>
> >> 7693 = Label
> >> 6 = ???
> >> 254 = I presume is the TTL
> >>
> >> What does the 6 represent??
> >
> > it's the EXP value. you're right about the last being the TTL.
> >
> > oli
>
> Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?

Hmm, why do you think so? Looking at the code, it only prints the 3 exp.
bits.

oli
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

bandwidth.user at gmail

Nov 17, 2009, 12:05 AM

Post #5 of 10 (787 views)
Permalink

Re: debug mpls packet [In reply to]

Oliver Boehmer (oboehmer) wrote:
>>>> Does anyone know what the middle number represents in a "debug mpls
>>>> packet" ( eg: {7963 6 254} )?
>>>> I can't find this information anywhere.
>>>>
>>>> 7693 = Label
>>>> 6 = ???
>>>> 254 = I presume is the TTL
>>>>
>>>> What does the 6 represent??
>>> it's the EXP value. you're right about the last being the TTL.
>>>
>>> oli
>> Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?
>
> Hmm, why do you think so? Looking at the code, it only prints the 3 exp.
> bits.

Cisco must have combined RFC3032 [2.1. Encoding the Label Stack] into
one value.

Roy
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

bandwidth.user at gmail

Nov 17, 2009, 12:19 AM

Post #6 of 10 (785 views)
Permalink

Re: debug mpls packet [In reply to]

roy wrote:
> Oliver Boehmer (oboehmer) wrote:
>>>>> Does anyone know what the middle number represents in a "debug mpls
>>>>> packet" ( eg: {7963 6 254} )?
>>>>> I can't find this information anywhere.
>>>>>
>>>>> 7693 = Label
>>>>> 6 = ???
>>>>> 254 = I presume is the TTL
>>>>>
>>>>> What does the 6 represent??
>>>> it's the EXP value. you're right about the last being the TTL.
>>>>
>>>> oli
>>> Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?
>>
>> Hmm, why do you think so? Looking at the code, it only prints the 3 exp.
>> bits.
>
> Cisco must have combined RFC3032 [2.1. Encoding the Label Stack] into
> one value.

Referring to EXP/CoS + S, that is.

Roy
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

oboehmer at cisco

Nov 17, 2009, 4:19 AM

Post #7 of 10 (775 views)
Permalink

Re: debug mpls packet [In reply to]

> >>>> Does anyone know what the middle number represents in a "debug
mpls
> >>>> packet" ( eg: {7963 6 254} )?
> >>>> I can't find this information anywhere.
> >>>>
> >>>> 7693 = Label
> >>>> 6 = ???
> >>>> 254 = I presume is the TTL
> >>>>
> >>>> What does the 6 represent??
> >>> it's the EXP value. you're right about the last being the TTL.
> >>>
> >>> oli
> >> Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?
> >
> > Hmm, why do you think so? Looking at the code, it only prints the 3
exp.
> > bits.
>
> Cisco must have combined RFC3032 [2.1. Encoding the Label Stack] into
> one value.

still not sure what you refer to, and why you think the debug discussed
shows the 4-bit Exp+S value rather than the 3-bit Exp only?

oli
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

bandwidth.user at gmail

Nov 17, 2009, 7:38 PM

Post #8 of 10 (773 views)
Permalink

Re: debug mpls packet [In reply to]

Oliver Boehmer (oboehmer) wrote:
>
>>>>>> Does anyone know what the middle number represents in a "debug
> mpls
>>>>>> packet" ( eg: {7963 6 254} )?
>>>>>> I can't find this information anywhere.
>>>>>>
>>>>>> 7693 = Label
>>>>>> 6 = ???
>>>>>> 254 = I presume is the TTL
>>>>>>
>>>>>> What does the 6 represent??
>>>>> it's the EXP value. you're right about the last being the TTL.
>>>>>
>>>>> oli
>>>> Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?
>>> Hmm, why do you think so? Looking at the code, it only prints the 3
> exp.
>>> bits.
>> Cisco must have combined RFC3032 [2.1. Encoding the Label Stack] into
>> one value.
>
> still not sure what you refer to, and why you think the debug discussed
> shows the 4-bit Exp+S value rather than the 3-bit Exp only?

If I may, MPLS Fundamentals refers to the stack on Fig 2-1 as
Label/EXP/BoS/TTL. It then breaks this on Example 3-8 with {label EXP
TTL}. All things held constant; label at 20, TTL at 8, then EXP must be 3+1.

Roy
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

deadheadblues at gmail

Nov 17, 2009, 8:09 PM

Post #9 of 10 (771 views)
Permalink

Re: debug mpls packet [In reply to]

On Tue, Nov 17, 2009 at 8:38 PM, roy <bandwidth.user [at] gmail> wrote:

> Oliver Boehmer (oboehmer) wrote:
>
>>
>>
>>> Does anyone know what the middle number represents in a "debug
>>>>>>>
>>>>>> mpls
>>
>>> packet" ( eg: {7963 6 254} )?
>>>>>>> I can't find this information anywhere.
>>>>>>>
>>>>>>> 7693 = Label
>>>>>>> 6 = ???
>>>>>>> 254 = I presume is the TTL
>>>>>>>
>>>>>>> What does the 6 represent??
>>>>>>>
>>>>>> it's the EXP value. you're right about the last being the TTL.
>>>>>>
>>>>>> oli
>>>>>>
>>>>> Could it be the 3-bit EXP and 1-bit Bottom of Stack Flag combined?
>>>>>
>>>> Hmm, why do you think so? Looking at the code, it only prints the 3
>>>>
>>> exp.
>>
>>> bits.
>>>>
>>> Cisco must have combined RFC3032 [2.1. Encoding the Label Stack] into
>>> one value.
>>>
>>
>> still not sure what you refer to, and why you think the debug discussed
>> shows the 4-bit Exp+S value rather than the 3-bit Exp only?
>>
>
> If I may, MPLS Fundamentals refers to the stack on Fig 2-1 as
> Label/EXP/BoS/TTL. It then breaks this on Example 3-8 with {label EXP TTL}.
> All things held constant; label at 20, TTL at 8, then EXP must be 3+1.
>
> Roy
>
> _______________________________________________
> cisco-nsp mailing list cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>

Reading too much into it. It's just not showing the stack bit. The output is
for information. You don't need to know the stack bit, its the only label.
And if there were more than one, then it would show all labels.
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

bandwidth.user at gmail

Nov 17, 2009, 9:25 PM

Post #10 of 10 (765 views)
Permalink

Re: debug mpls packet [In reply to]

Hobbs wrote:
>
>
> On Tue, Nov 17, 2009 at 8:38 PM, roy <bandwidth.user [at] gmail
> <mailto:bandwidth.user [at] gmail>> wrote:
>
> Oliver Boehmer (oboehmer) wrote:
>
>
>
> Does anyone know what the middle number
> represents in a "debug
>
> mpls
>
> packet" ( eg: {7963 6 254} )?
> I can't find this information anywhere.
>
> 7693 = Label
> 6 = ???
> 254 = I presume is the TTL
>
> What does the 6 represent??
>
> it's the EXP value. you're right about the last
> being the TTL.
>
> oli
>
> Could it be the 3-bit EXP and 1-bit Bottom of Stack
> Flag combined?
>
> Hmm, why do you think so? Looking at the code, it only
> prints the 3
>
> exp.
>
> bits.
>
> Cisco must have combined RFC3032 [2.1. Encoding the Label
> Stack] into
> one value.
>
>
> still not sure what you refer to, and why you think the debug
> discussed
> shows the 4-bit Exp+S value rather than the 3-bit Exp only?
>
>
> If I may, MPLS Fundamentals refers to the stack on Fig 2-1 as
> Label/EXP/BoS/TTL. It then breaks this on Example 3-8 with {label
> EXP TTL}. All things held constant; label at 20, TTL at 8, then EXP
> must be 3+1.
>
> Roy
>
> _______________________________________________
> cisco-nsp mailing list cisco-nsp [at] puck
> <mailto:cisco-nsp [at] puck>
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
>
> Reading too much into it. It's just not showing the stack bit. The
> output is for information. You don't need to know the stack bit, its the
> only label. And if there were more than one, then it would show all labels.

Right on, too much reading. I didn't take the text as it is. Oli was on
spot. Cheers!

Roy
_______________________________________________
cisco-nsp mailing list cisco-nsp [at] puck
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

Index | Next | Previous | View Threaded

Interested in having your list archived? Contact Gossamer Threads