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

[Jouni Korhonen <[e-mail]>]

Loa,

What I still do not get is.. the picture you have below is the same except I used T-labels and you used L-labels. So what is the real difference? 

I have used T-labels as those that change between P-nodes. And when I need to carry PWs over DA-*-PE unchanged i.e., make a DA-*-PE behave like a P-node, I used L-labels to build my overlay. Still T-labels being there between each P-node.

- Jouni




> On Mar 12, 2017, at 11:03 PM, Loa Andersson <[e-mail]> wrote:
> 
> 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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>>> https://www.ietf.org/mailman/listinfo/detnet-dp-dt
>> 
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> 
> -- 
> 
> 
> Loa Andersson                        email: [e-mail]
> Senior MPLS Expert                          [e-mail]
> Huawei Technologies (consultant)     phone: [phone]