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

[Huub van Helvoort <[e-mail]>]

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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