RE: I-D Action:draft-takacs-ccamp-revertive-ps-00.txt

["Attila Takacs" <[e-mail]>]

Hi Dimitri,

Thanks for the comments!
Pease see inline.
Best regards,
Attila 

> -----Original Message-----
> From: PAPADIMITRIOU Dimitri 
> [mailto:[e-mail]] 
> Sent: Wednesday, July 09, 2008 2:55 PM
> To: Attila Takacs; Loa Andersson; ccamp
> Subject: RE: I-D Action:draft-takacs-ccamp-revertive-ps-00.txt
> 
> attila,
> 
> once you are at it, can u explain the following "to properly 
> setup the remote data plane endpoints" ? what it actually 
> means in the context:
> 
> "Such an example is protection switching of bidirectional  
> connections in Ethernet PBB-TE [IEEE-PBBTE] (currently under  
> standardisation in IEEE).  In this case revertiveness needs 
> to be  signalled by RSVP-TE during LSP establishment to 
> properly setup the  remote data plane endpoint."
> 

With regards to PBB-TE, 1:1 bidirectional protection with or without
reversion is supported by the data plane and are executed in data plane
independently of management or external signaling. However, this
requires to configure both endpoints the same way, i.e., protection with
or without reversion. For this RSVP-TE needs to add signaling of the
revertive property.

> also do u need a V bit, or isn't the WTR time with a reserved 
> value not sufficient e.g. 0x0 ? when for inst. the locally 
> configured timer would be used (no timer signaled).
> 

Agreed, we would not need a bit if we had a WTR field with a reserved
value. On the other hand, if the WTR value is not required to change on
a per-LSP basis, which is possibly the general case, we would not need a
WTR field occupying several bits, instead just have single revertive
bit.

> the revertive operation is associated to LSP right ? why did 
> you pull this into the 16-bit space for Link specific 
> operation (before link flags ?)
> 

I think there are options to place this information:

-it could have a dedicated bit (V) as it is in the ID
-alternatively reversion may be added to LSP Flags as a specific
protection type (e.g., adding new types such as Revertive 1:N
Protection, Revertive 1+1 Bidirectional Protection,...)

-you are right about the WTR time, it should go before the LSP Flags 




> thx,
> -d.
> > -----Original Message-----
> > From: [e-mail]
> > [mailto:[e-mail]] On Behalf Of Attila Takacs
> > Sent: Wednesday, July 09, 2008 2:34 PM
> > To: Loa Andersson; ccamp
> > Subject: RE: I-D Action:draft-takacs-ccamp-revertive-ps-00.txt
> > 
> > Hi Loa,
> > 
> > I assume a part of your comment/question relates to problems with 
> > reversion if LSP setup and holding priorities are 
> mismatched. In this 
> > case the worker may be already deleted before the reversion 
> would take 
> > place. This is certainly an interesting question...
> > 
> > ...at a first thought an explicit revertive bit may be used to 
> > override the priorities for LSPs with revertive protection.
> > 
> > Best regards,
> > Attila
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > > -----Original Message-----
> > > From: Loa Andersson [mailto:[e-mail]]
> > > Sent: Wednesday, July 09, 2008 12:01 PM
> > > To: ccamp; Attila Takacs
> > > Subject: Re: I-D Action:draft-takacs-ccamp-revertive-ps-00.txt
> > > 
> > > Attila,
> > > 
> > > a neat draft that does what it sets out to do. For the 
> moment I've 
> > > no actual comments on the draft itself (might have when 
> I'd time to 
> > > think about in detail), but more meta-question.
> > > 
> > > It is not a given that the revertive behavior always is 
> beneficial. 
> > > In networks that are very dynamic it might be optional to revert, 
> > > let the traffic stay on the protecting path or replace them 
> > > altogether.
> > > 
> > > Wouldn't it be interesting to discuss more in detail when a 
> > > revertive behavior is needed/wanted and when it is not.
> > > 
> > > /Loa
> > > 
> > > [e-mail] wrote:
> > > > A New Internet-Draft is available from the on-line
> > > Internet-Drafts directories.
> > > > 
> > > > 	Title           : GMPLS RSVP-TE recovery extension for 
> > > data plane initiated reversion
> > > > 	Author(s)       : A. Takacs, B. Tremblay
> > > > 	Filename        : draft-takacs-ccamp-revertive-ps-00.txt
> > > > 	Pages           : 11
> > > > 	Date            : 2008-07-06
> > > > 
> > > > RSVP-TE recovery extensions are specified in [RFC4872] and
> > > [RFC4873].
> > > > Currently these extensions cannot signal request for revertive 
> > > > protection to the remote endpoint.  This document defines a
> > > new bit to
> > > > signal this request and a new field to specify a 
> wait-to-restore 
> > > > interval.Requirements Language
> > > > 
> > > > The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
> > "SHALL NOT",
> > > > "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
> > > "OPTIONAL" in this
> > > > document are to be interpreted as described in
> > > > 
> > > > A URL for this Internet-Draft is:
> > > > 
> > > 
> > 
> http://www.ietf.org/internet-drafts/draft-takacs-ccamp-revertive-ps-00
> > > > .txt
> > > > 
> > > > Internet-Drafts are also available by anonymous FTP at:
> > > > ftp://ftp.ietf.org/internet-drafts/
> > > > 
> > > > Below is the data which will enable a MIME compliant 
> mail reader 
> > > > implementation to automatically retrieve the ASCII 
> version of the 
> > > > Internet-Draft.
> > > > 
> > > > 
> > > > 
> > > 
> > 
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> > > 
> > > --
> > > Loa Andersson
> > > 
> > > Principal Networking Architect
> > > Acreo AB                           phone:  [phone]
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> > >                                             [e-mail]
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> > 
> > 
>