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

[Loa Andersson <[e-mail]>]

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]