Subject: Re: MH-PW vs MS-PW

From: Chris Metz <[email-masked]>
Date: Mon, 21 Mar 2005 16:51:10 -0800

At 03:39 PM 3/21/2005 -0700, Luca Martini wrote:
>WG,
>
>I would like to make absolutely sure that we agree on the terminology of 
>the Multi????-PW.
>
>We used the Multi Hop PW until now, however we received feedback that 
>Multi segment Pw would be more appropriate, as there is no precise 
>definition of "Hop".
>Since we will be using this term in drafts names , and throughout multiple 
>documents, I would like to settle the terminology definition before hand.
>
>Are there any objections to using the term Multi Segment Pseudo Wire 
>instead of Multi Hop Pseudo Wire? ( MS-PW )

No ... I don't think so. A hop was meant to imply a PE that at a minimum 
terminated a PWE3 control channel
(i.e. LDP) and performed PW label processing. A segment is a more general 
term that
covers both.

I sense though that the term "hop" will re-appear as we think about different
MH-PW ...er MS-PW signaling techniques.

Chris

>Thanks.
>Luca
>
>_______________________________________________
>pwe3 mailing list
>[email-masked]
>https://www1.ietf.org/mailman/listinfo/pwe3

---

From: David McDysan <[email-masked]>
Date: Tue, 22 Mar 2005 08:37:29 -0500

I think there needs to be a more precise definition of segment. Below is the
current draft definition:

4. Terminology

   [PWE3-REQ] provides terminology for PWE3. This document defines the
   following additional terms:

     - Ultimate PE (U-PE).  A PE where the customer-facing ACs
       (attachment circuits) are bound to a PW forwarder. An ultimate PE
       is present in the first and last segments of a MS-PW.

     - Single-Segment PW (SS-PW). A PW setup directly between two U-PE
       devices. Each LSP in one direction of a SS-PW traverses one PSN
       tunnel that connects the two U-PEs.

     - Multi-Segment PW (MS-PW).  A static or dynamically configured set
       of two or more contiguous PW segments
        that behave and function as a single point-to-point PW. Each end
       of a MS-PW by definition MUST terminate on a U-PE.

     - PW Switching Provider Edge (S-PE).  A PE capable of switching the
       control and data planes of the preceding and succeeding PW
       segments  in a MS-PW. It is therefore a PW switching point for a
       MS-PW. A PW Switching Point is never the S-PE and the U-PE for
       the same MS-PW. A PW switching point runs necessary protocols to
       setup and manage PW segments with other PW switching points and
       ultimate PEs.

     - PW Segment. A part of a single-segment or multi-segment PW, which
       is set up between two PE devices, U-PEs and/or S-PEs.

>From reading the above definition, it is unclear to me whether a segment of
a multi-segment PW the same as a single segment PW?

I recommend that the requirements need to specify at least PW segment OAM
functions, signaling, routing, QoS.

Dave

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of Luca Martini
> Sent: Monday, March 21, 2005 5:39 PM
> To: PWE3 WG (E-mail)
> Subject: [PWE3] MH-PW vs MS-PW
> 
> WG,
> 
> I would like to make absolutely sure that we agree on the 
> terminology of the Multi????-PW.
> 
> We used the Multi Hop PW until now, however we received 
> feedback that Multi segment Pw would be more appropriate, as 
> there is no precise definition of "Hop".
> Since we will be using this term in drafts names , and 
> throughout multiple documents, I would like to settle the 
> terminology definition before hand.
> 
> Are there any objections to using the term Multi Segment 
> Pseudo Wire instead of Multi Hop Pseudo Wire? ( MS-PW )
> 
> 
> Thanks.
> Luca
>