Re: [Detnet-dp-dt] Using MS-PW concept for the d-pw

[Jouni Korhonen <[e-mail]>]

Loa,

Ok. Point taken. Global is bad wording. I try to remember to use e2e from now on.

- Jouni

> On 25 Feb 2017, at 21:05, Loa Andersson <[e-mail]> wrote:
> 
> Jouni,
> 
> On 2017-02-26 12:36, Jouni Korhonen wrote:
>> Yuanlong,
>> 
>> 
>>> On 25 Feb 2017, at 02:02, Jiangyuanlong <[e-mail]> wrote:
>>> 
>>> Loa,
>>> 
>>> -----Original Message-----
>>> From: Loa Andersson [mailto:[e-mail]]
>>> Sent: Saturday, February 25, 2017 3:34 PM
>>> To: Jiangyuanlong; Jouni Korhonen
>>> Cc: [e-mail]
>>> Subject: Re: [Detnet-dp-dt] Using MS-PW concept for the d-pw
>>> 
>>> Yuanlong,
>>> 
>>> The L-laabel is ther to make the the intermediate not (S-PE) know what to do whit the packet, the d-pw label was not allocated by the S-PE, so it does not ahve any knowledge what it means.
>>> [YJ] d-pw can be allocated by the S-PE in MS-PW, just as you would like to allocate the L-labels. Very similarly, I think the same T-LDP protocol can be used.
>>> [YJ] As I said in the previous email, using PW to trigger FRER will be cleaner compared with using L-label since CW is inspected.
>> 
>> I think you are still getting it wrong what was intended with L-labels. They were specifically thought in the context of detnet global d-pw labels.
> 
> hmmmm -yes, but not in the sense that the mpls wg use "global", the
> special purpose labels are global, they mean the same thing where ever
> you find them. Here we have end-to-end labels, labels that stays the
> same all through the forwarding process in the network.
> 
> /Loa
> 
>> 
>> L-labels connected MS-PW nodes over the network topology. All FRER “triggering” etc is still and has always been tied to the d-pw. Within a S- or T-PE you need to pop the L-label and then inspect the top of stack d-pw label..
>> 
>>                                                 within
>>    LSR                         |------------- S- or T-PE -------------|
>>                    PHP                            POP
>>                  -------->                     -------->
>> +------------+                  +------------+            +------------+
>> |  T-labels  |                  |  L-label   |            | d-pw label |
>> +------------+                  +------------+            +------------+
>> |  L-label   |                  | d-pw label |            |            |
>> +------------+                  +------------+            |  Payload   |
>> | d-pw label |                  |            |            |            |
>> +------------+                  |  Payload   |            +------------+
>> |            |                  |            |
>> |  Payload   |                  +------------+
>> |            |
>> +------------+
>> 
>> 
>> This allowed also bypassing S-PE easily for some L-labels.. instead of an L-label pop one would do a swap and just forward after that.
>> 
>> 
>> - Jouni
>> 
>> 
>>> If you let the S-PEs allocate and swap d-pw's, the next S-PE or a T-PE can't coordinate for the same packet coming in on from tow different nodes.
>>> [YJ] It's like the 1+1 PW protection case, though the operations of elimination and replication in the S-PE and the T-PE need to be specified.
>>> [YJ]Take VPLS as an example, several PWs can be directed into the same VSI in a PE and PW packets are processed there (for detnet, the processing is FRER now).
>>> 
>>> But I feel like we are going in circles, can we agree on the corner stones first?
>>> 
>>> Do we want all possible/conceivable control mechanism be within scope?
>>> [YJ] maybe we can take LDP as a first step. It seems the difficulty is how to decide the S-PEs for a detnet flow (a routing protocol may be needed for automatic selection).
>>> [YJ] if all T-PEs and S-PEs are determined for a detnet flow, it is quite easy to set up PW segments and LSPs respectively with the help of LDP protocol.
>>> Cheers,
>>> Yuanlong
>>> 
>>> /Loa
>>> 
>>> 
>>> On 2017-02-25 15:18, Jiangyuanlong wrote:
>>>> I agreed to alternative 2. L-label is not needed, S-PE must look into the PW label (further, extract sequence number in the CW) of a packet, and all FRER semantics can be coupled with the PW label.
>>>> 
>>>> -----Original Message-----
>>>> From: Jouni Korhonen [mailto:[e-mail]]
>>>> Sent: Saturday, February 25, 2017 3:07 PM
>>>> To: Jiangyuanlong
>>>> Cc: [e-mail]; Loa Andersson
>>>> Subject: Re: [Detnet-dp-dt] Using MS-PW concept for the d-pw
>>>> 
>>>> Hi,
>>>> 
>>>>> [YJ] I regard the L-Labels and T-labels are the same LSP layer. If we look into the full MPLS label stack of a packet in a PW, normally there is an LSP label at the top (unless PHP is enabled for the last hop).
>>>>> Not sure what is the L-Label in your picture, is it different from LSP label?
>>>> 
>>>> L-labels have been so far in the discussion between MS-PW PEs.
>>>> T-labels are between any LSR. L-labels are not PHPed i.e., even if PHP
>>>> is enable the L-Label stays and the label above it gets popped (that
>>>> we have been referring as T-Labels). T- and L-labels are just a naming
>>>> convention. IF you don’t have “between MS-PW PEs” semantic associated
>>>> with the L-Label, it is the same as T-Label ;)
>>>> 
>>>> 
>>>> 
>>>> case L-labels are present.. (alternative 1)
>>>> 
>>>>                    PHP
>>>>                  -------->
>>>> +------------+                  +------------+
>>>> |  T-labels  |                  |  L-label   |
>>>> +------------+                  +------------+
>>>> |  L-label   |                  | d-pw label |
>>>> +------------+                  +------------+
>>>> | d-pw label |                  |            |
>>>> +------------+                  |  Payload   |
>>>> |            |                  |            |
>>>> |  Payload   |                  +------------+
>>>> |            |
>>>> +------------+
>>>> 
>>>> case no L-labels.. (alternative 2.. and also alternative 3 if you
>>>> think T- and L-labels are the same)
>>>> 
>>>>                    PHP
>>>>                  -------->
>>>> +------------+                  +------------+
>>>> |  T-labels  |                  | d-pw label |
>>>> +------------+                  +------------+
>>>> | d-pw label |                  |            |
>>>> +------------+                  |  Payload   |
>>>> |            |                  |            |
>>>> |  Payload   |                  +------------+
>>>> |            |
>>>> +------------+
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> - Jouni
>>>> 
>>> 
>>> --
>>> 
>>> 
>>> Loa Andersson                        email: [e-mail]
>>> Senior MPLS Expert                          [e-mail]
>>> Huawei Technologies (consultant)     phone: [phone]
>>> _______________________________________________
>>> Detnet-dp-dt mailing list
>>> [e-mail]
>>> https://www.ietf.org/mailman/listinfo/detnet-dp-dt
>> 
>> _______________________________________________
>> Detnet-dp-dt mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/detnet-dp-dt
>> 
> 
> -- 
> 
> 
> Loa Andersson                        email: [e-mail]
> Senior MPLS Expert                          [e-mail]
> Huawei Technologies (consultant)     phone: [phone]
> 
> _______________________________________________
> Detnet-dp-dt mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/detnet-dp-dt