Re: [Detnet-dp-dt] New update of the draft available

[Loa Andersson <[e-mail]>]

Jouni,

I'm sorry if I caused the confusion. A PW needs the PSN Tunnel, we have
called L-Label because we use it for overlay also.

On 2017-03-13 07:44, Jouni Korhonen wrote:
> I think there’s still a bit of confusion what constitutes T and L labels. Say I have a topology below:
>
>
>           DA-T-PE     P       P       Php      DA-S-PE       Php    DA-T-PE
> PW label     200      200     200     200    200 swp 300     300    300
> L label
> T label          123  swp 124 swp 125 pop                131 pop

Yes - but you don't need the T-label (it is optional), and only tunnel 
part of the way between two DA-*-PEs.

I think this is the case
                        php                     php
         DA-T-PE  P      P     DA-S-PE    P      P    DA-T-PE
PW label    20   20    20    20 swp 30  30     30    terminate
L label     13   14    php     push 40  50     php
T label          <optional>

If you want we can talk about it, if you are online now.

/Loa

>
> Why would I need L-labels in the above case?
>
>           DA-T-PE     P       P       Php      DA-S-PE       Php    DA-T-PE
> PW label     200      200     200     200         200        200    200
> L label      300      300     300     300    300 swp 400     400    400
> T label          123  swp 124 swp 125 pop                131 pop
>
> Here I could use the L-label to bypass DA-S-PE.
>
> Correct me if this is not correct assumption..
>
>
> - Jouni
>
>
>
>
>> On Mar 10, 2017, at 6:38 PM, Loa Andersson <[e-mail]> wrote:
>>
>> Jouni,
>>
>> Mostly looks very good, the thing I don't understand is why you still say that the L-label is optional, it really isn't.
>>
>> - we need it to deliver the d-pw label unchanged
>> - since we can't guarantee that the "P" nodes are not able to do
>>  DetNet NSP, we can't set up the d-pw label with signaling that
>>  exposes the "request for DetNet NSP/FRER" to P nodes.
>> - needed for protection
>> - the end-to-end tunnel must be the innermost tunnel, carrying
>>  pw label
>>
>> There is one case, if two DA-*-PEs are immediately adjacent, there the
>> L-lable will be an implicit NULL label and not appear in the stack, but
>> for the control plane it is there.
>>
>> /Loa
>>
>> On 2017-03-11 07:25, Jouni Korhonen wrote:
>>> * Added Loa’s comments on the L-label.
>>> * Added Janos’ comments.
>>> * Added extended forwarder text.
>>> * Added (speculative text.. can be removed) D bit to flow-id word so that we can check in a ring case the direction of the flow (note this does not double history buffer space as claimed.. did not bother to fix that)
>>> * reworked the PW encapsulation pictures.
>>> * Added more content to DA-*-PE descriptions.
>>>
>>> - Jouni
>>>
>>>
>>
>> --
>>
>>
>> Loa Andersson                        email: [e-mail]
>> Senior MPLS Expert                          [e-mail]
>> Huawei Technologies (consultant)     phone: [phone]
>>
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>
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-- 


Loa Andersson                        email: [e-mail]
Senior MPLS Expert                          [e-mail]
Huawei Technologies (consultant)     phone: [phone]