Re: [Detnet-dp-dt] one question on S-DetNet-PEs

[Balázs Varga A <[e-mail]>]

Hi,

Correct. My comment was an additional argument for the tunnels.
There are two scenarios mandating tunnels:
1, regular P nodes
2, DA-S-PE nodes acting as P node for some PWs 

Cheers
Bala'zs 

-----Original Message-----
From: Loa Andersson [mailto:[e-mail]] 
Sent: Thursday, March 09, 2017 11:11 AM
To: Balázs Varga A <[e-mail]>om>; [e-mail]; [e-mail]
Subject: Re: [Detnet-dp-dt] one question on S-DetNet-PEs

Balázs,

inline please.

On 2017-03-09 17:02, Balázs Varga A wrote:
> Hi,
>
> Generally agree, just two additional notes/comments:
> - Mandatory tunnels:
> They are needed anyway for regular P nodes. The DetNet role of 
> intermediate "P" nodes is limited to ensure congestion protection.  
> However P nodes can usually recognize only LSP labels and cannot 
> consider the whole label stack for flow recognition.  Therefore if 
> DetNet flows would not use tunnels P nodes may not distinguish them 
> from regular (non-DetNet) flows and cannot achieve congestion protection.

While I agree to this, and it is another nail in the coffin of thw "we don't need", you are changing the scenario I draw. The point I tried to make was that DA-S-PE capable nodes in some scenarios might serve in a P role in some scenarios - the operators choice.

/Loa


>
> - DA-S-PE needs also PW and FRER specific configuration:
> As clarification to the step when "DetNet-PW-label is allocated by the 
> DA-S-PE for the DA-T-PE". You wrote:
>    > the DetNet-PW-label is allocated by the DA-S-PE for the DA-T-PE, and
>    >  as the LSP is set up an instruction is entered into the LFIB whether
>    >  the DA-S-PE should do FRER or not.
> I think we need more than a simple instruction "to do FRER or not". 
> The egress replication on the DA-S-PE (towards the next DA-S-PE(s) or 
> the terminating
> DA-T-PE) may be DetNet-flow specific (how many member flows should be 
> created, which tunnel should be used by the egress member flows, etc.).
>
> I think we do not have signaling for that DetNet-flow and FRER specific configuration.
> Do we intend to configure them in advance via management?
>
> Cheers
> Bala'zs
>
> -----Original Message-----
> From: Detnet-dp-dt [mailto:[e-mail]] On Behalf Of 
> Loa Andersson
> Sent: Thursday, March 09, 2017 2:31 AM
> To: [e-mail]; [e-mail]
> Subject: Re: [Detnet-dp-dt] one question on S-DetNet-PEs
>
> Jouni, et.al.,
>
> On 2017-03-09 04:18, Jouni Korhonen wrote:
>> Good guestion.
>>
>> I guess, if you want a specific node to be a S-DetNet-PE for some 
>> overlay and P for other, you could "tunnel" through it in P case.
>
> Yes - I think that is necessary. There is a bit more too it though.
>> The
>> currect draft still has text for "overlay labels" (i.e., L-labels) 
>> and I think those would work nicely for this case as you say below.
>
> OK - leave that in! There is a terminology issue here, the way we are doing things now, the L-label is the PSN tunnel in the PW architecture.
>
> The caveat is that PSN tunnel needsto be mandatory, unless you want to have a very complicated configuration for when a node is P for one overlay but DA-S-PE for another.
>
> Let me see if I got right
>
> - the PSN-tunnel (PHP'ed at the P node adjacent to the DA-S-PE) takes
>    the DetNet PW to the DA-S-PE.
>
> - the DetNet-PW-label is allocated by the DA-S-PE for the DA-T-PE, and
>    as the LSP is set up an instruction is entered into the LFIB whether
>    the DA-S-PE should do FRER or not.
>
> - DA-T-PE establish a PSN-tunnel through which the DetNet PW is
>    tunneled.
>
> - in the case of using a signaling protocol (since this is PWs I guess
>    it by default is LDP) to establish the PW, no other node than the
>    DA-S-PE, and the egress (DA-T-PE) sees the request for FRER.
>
> - for signaling the L-Label/PSN tunnel, RSVP-TE could be used, which
>    means that the L-Label/PSN-tunnel also serves at BW container.
>
> Did I get that right?
>
> Yes I think it will work.
>
> /Loa
>
>>
>> - Jouni
>>
>> 3/8/2017, 5:03 AM, Loa Andersson kirjoitti:
>>>
>>> Folks,
>>>
>>> There might be a simple answer, but I don't see it just now.
>>>
>>> Suppose we have a network, where we designate a certain number of 
>>> nodes as S-DetNet-PEs, to build a nice overlay DetNet.
>>>
>>> Assume that we also designate another set of nodes as S-DetNet-PEs 
>>> for another overlay DetNet.
>>>
>>> Also assume that some nodes that are S-DetNet-PE in one network are 
>>> P's in the other.
>>>
>>> If we signal that we have have a detnet-ms-pw going through a P node 
>>> that is capable of doing elimination/replication, how do we stop the 
>>> P-node from doing that?
>>>
>>> This was something that the T-Lables did for us.
>>>
>>> /Loa
>

-- 


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