Re: [CCAMP] Comment on compatibility in draft-takacs-ccamp-revertive-ps

[Francesco Fondelli <[e-mail]>]

Hi,

> They will provision default values per layer in the network.

Many years ago we had a request (for a gmpls-controlled sdh network)
to control hoff on a per connection basis. Some connections were
supporting a form of protection switching at upper layer. Other
connections (at the same layer) were supported by a form of protection
switching in the lower layer. They wanted different hold off timers
(default was 100ms if I am not wrong). They also pointed me to
"Hold-off times are useful for interworking of protection schemes. The
objective is that these times should be provisionable on an individual
VC basis" [G.841]. No idea what OTN or WDM recommendations say about
this point.

> A nice note.  Dou you think this draft is gilding the lily?

I do not know, it might. All I know is that during the past 5 years I
sporadically receive the request described above. I typically reply
with a link to this draft.

thanks
ciao
fra

On Wed, Nov 13, 2013 at 10:10 PM, Huub van Helvoort
<[e-mail]> wrote:
> Hello John,
>
> You replied:
>
>> A nice note.  Dou you think this draft is gilding the lily?
>
>
> Yes, indeed.
>
> Regards, Huub.
>
>
>
>>> -----Original Message-----
>>> From: [e-mail] [mailto:[e-mail]] On Behalf
>>> Of Huub van Helvoort
>>> Sent: Wednesday, November 13, 2013 12:53 PM
>>> To: [e-mail]
>>> Subject: Re: [CCAMP] Comment on compatibility in draft-takacs-ccamp-
>>> revertive-ps
>>>
>>> Hello Zafar,
>>>
>>> You wrote:
>>>
>>>   > The default parameter value in data plan is deficient for the  >
>>> following
>>> reasons:
>>>>
>>>>
>>>>   1. We cannot differentiate between revertive and non-revertive
>>>> behavior
>>>>      using default value of wait-to-restore timer.
>>>
>>>
>>> The value of the WTR timer should not determine the (non-)revertive
>>> behavior.
>>> The (non-)revertive behaviour should be explicitly provisioned.
>>>
>>>>      E.g., as far
>>>>      as I remember default value for WRT is 0, which means protection
>>>>      is non-revertive.
>>>
>>>
>>> The typical default value for WTR is 5 minutes to provide a hysteresis,
>>> it can be
>>> overruled by a higher priority event like Sf or SD.
>>> Setting the value of WTR to 0 does not mean protection is non-revertive.
>>>
>>>>      So this default does not work for revertive
>>>>      protection. I.e., the data plan default cannot cover both revertive
>>>>      and non-revertive cases.
>>>
>>>
>>> Again: the WTR value should not be used to indicate (non-)revertive
>>> behavior.
>>>
>>>>   2. Correct setting for wait-to-restore and hold-off timers need to
>>>>      account for differential delays between working and protection
>>>> paths.
>>>
>>>
>>> No, WTR accounts for repair of the failed path and to encertain that the
>>> repair
>>> can be trusted.
>>> Hold-off timers are used to allow protection switching in layers closer
>>> to the
>>> physical layer to complete before protection switching in the affected
>>> layer.
>>>
>>>> In summary, default values cannot cover all use cases. Hence, SP
>>>> typically wants to set revertive vs. non-revertive behavior,
>>>> wait-to-restore and hold-off timers on per connection basis.
>>>
>>>
>>> They will provision default values per layer in the network.
>>>
>>> Regards, Huub.
>>>
>>> ===========
>>>>
>>>> From: Dieter Beller <[e-mail]
>>>> <mailto:[e-mail]>>
>>>> Organization: Alcatel-Lucent
>>>> Date: Sunday, November 10, 2013 9:07 AM
>>>> To: zali <[e-mail] <mailto:[e-mail]>>
>>>> Cc: "[e-mail] <mailto:[e-mail]>" <[e-mail]
>>>> <mailto:[e-mail]>>, "[e-mail] <mailto:[e-mail]>"
>>>> <[e-mail] <mailto:[e-mail]>>
>>>> Subject: Re: [CCAMP] Comment on compatibility in
>>>> draft-takacs-ccamp-revertive-ps
>>>>
>>>>      Hi Zafar,
>>>>
>>>>      this draft is defining signaling extensions for the hold-off time
>>>> as
>>>>      well as the wait-to-restore time for protected LSPs
>>>>      where applicable.
>>>>
>>>>      There are default values set for these timers in the data plane and
>>>>      signaling them in the control plane makes only
>>>>      sense if the timer values shall differ from the default values. Do
>>>>      you see a need for that? IMO, operators typically
>>>>      use the defaults and do not set these values on a per connection
>>>> basis.
>>>>
>>>>
>>>>      Thanks,
>>>>      Dieter
>>>>
>>>>
>>>>      On 08.11.2013 22:11, Zafar Ali (zali) wrote:
>>>>>
>>>>>      Hi Lou-
>>>>>
>>>>>      You are right, the ctype is TBD, like I mentioned during the
>>>>> meeting that
>>>>>      we are using different ctype.
>>>>>
>>>>>      We would like to take this opportunity to solicit comments from
>>>>> the WG
>>>
>>> on
>>>>>
>>>>>      this draft.
>>>>>
>>>>>      Thanks
>>>>>
>>>>>      Regards Š Zafar
>>>>>
>>>>>      -----Original Message-----
>>>>>      From:"[e-mail]"  <[e-mail]>
>>>>>      Date: Thursday, November 7, 2013 6:17 PM
>>>>>      To: zali<[e-mail]>,"[e-mail]"  <[e-mail]>
>>>>>      Subject: Comment on compatibility in
>>>>> draft-takacs-ccamp-revertive-ps
>>>>>
>>>>>>      Zafar,
>>>>>>         My comment in today's session was that you are redefining the
>>>>>> format
>>>
>>> of
>>>>>>
>>>>>>      an existing object (by adding TLVs) this breaks compatibility.
>>>>>> You
>>>>>>      stated that this wasn't the case.
>>>>>>
>>>>>>      FWIW:
>>>>>>
>>>>>>      Your document says:
>>>>>>
>>>>>>          0                   1                   2                   3
>>>>>>          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
>>>>>> 1
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>         |            Length             | Class-Num(37) |   C-Type(2)
>>>>>> |
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>         |S|P|N|O| Reserved  | LSP Flags |      Reserved     | Link
>>>>>> Flags|
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>         |I|R|   Reserved    | Seg.Flags |           Reserved
>>>>>> |
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>         |
>>>>>> |
>>>>>>         ~                           sub-TLVs
>>>>>> ~
>>>>>>         |
>>>>>> |
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>
>>>>>>
>>>>>>      RFC4872 says
>>>>>>            0                   1                   2
>>>>>> 3
>>>>>>            0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
>>>>>> 0 1
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>           |            Length             | Class-Num(37) | C-Type (2)
>>>>>> |
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>           |S|P|N|O| Reserved  | LSP Flags |     Reserved      | Link
>>>>>> Flags|
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>           |                           Reserved
>>>>>> |
>>>>>>
>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>>>
>>>>>>      Perhaps you meant C-Type(TBD).  You should address compatibility
>>>>>>      explicitly in any case.
>>>>>>
>>>>>>      Lou
>>>>>
>>>>>      _______________________________________________
>>>>>      CCAMP mailing list
>>>>>      [e-mail]://www.ietf.org/mailman/listinfo/ccamp
>>>>
>>>>
>
>
> --
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