RE: [PWE3] question regarding draft-kamapabhava-fr-pwe3-01.txt

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Tue, 18 Jun 2002, Claude Kawa wrote:

> In frame relay the reference used to determine whether the direction of the
> traffic is the forward or backward direction is the frame being forwarded.
> The forward direction is the direction taken by the frame being forwarded.
>
> The backward direction is the direction opposite to the direction taken by a
> frame being forwarded.
>
> So if a frame is traveled from East to West, relative to this frame, the
> forward direction  is the East-West direction and the backward direction is
> the West-East direction.
>
> We added these clarifications in the new FR/PWE3 draft to be available soon.

Do you mean
http://www.ietf.org/internet-drafts/draft-martini-frame-encap-mpls-01.txt

Abstract

   This document defines frame relay pseudo-wire emulation edge-to-edge.
   A frame relay pseudo-wire is a mechanism that exists between a
   provider's edge network nodes and support as faithfully as possible
   frame relay services over IP and MPLS packet switched network (PSN).
   Two mapping modes are defined: One-to-one mapping mode characterized
   by a one to one relationship between a frame relay VC and a pair
   of MPLS LSPs is defined for MPLS PSN. The other mode is known as port
   mode or many-to-one mapping mode and is defined for MPLS PSN and IP
   PSN with L2TPv3.


> About the processing of the different frame relay control bits (F, B, C, D)
> we copied almost  verbatim  the relevant text from ITU-T Recommendation
> Q.922 on frame relay data transfer protocol to avoid any misalignment.

FBDC - yes, that's efficient. A very nice mpls draft...

L.

> Claude Kawa
>
>
>
> -----Original Message-----
> From: Akiva Sadovski [mailto:akiva@AXERRA.com]
> Sent: Sunday, June 02, 2002 9:28 AM
> To: pwe3@ietf.org
> Subject: [PWE3] question regarding draft-kamapabhava-fr-pwe3-01.txt
>
>
> Hi, pwe3,
>
>
> In draft-kamapabhava-fr-pwe3-01:
>   1. the FRoPW header (control word) contains F and B bits;
>   2. the F-bit (FECN) definition is " FECN is copied as follows into the
> FRFoPW header: If it was set to one in the incoming frame relay frame, it
> must be copied unchanged in the FRoPW header. Otherwise if it was set to
> zero, it may be set to zero or one, depending on the congestion state of the
> PE device in the forward direction" (6.2.1)
>   3. it is stated in B-bit definition that the processing is as for F-bit,
> but ... it's applied in backward direction.
>   4. now the question: what direction in PW is considered to be backward:
> PSN-bound? CE-bound?
> i'm sure this issue was extensively discussed on this mail list, so how can
> i found any pointers ?
>
> thanks,
>    Akiva

<http://www.ee.surrey.ac.uk/Personal/L.Wood/><L.Wood@surrey.ac.uk>



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