Document Action: 'Structure-aware TDM Circuit Emulation Service over Packet Switched Network (CESoPSN)' to Informational RFC

[The IESG <iesg-secretary at ietf.org>]

The IESG has approved the following document:

- 'Structure-aware TDM Circuit Emulation Service over Packet Switched 
   Network (CESoPSN) '
   <draft-ietf-pwe3-cesopsn-07.txt> as an Informational RFC

This document is the product of the Pseudowire Emulation Edge to Edge 
Working Group. 

The IESG contact persons are Mark Townsley and Jari Arkko.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-pwe3-cesopsn-07.txt

Technical Summary

This draft extends the work described in RFC4553 by describing one
method of encapsulating structured (NxDS0) Time Division Multiplexed
(TDM) signals as pseudo-wires over packet-switching networks (PSN).

The use of a structure aware method of emulating NxDS0 circuits provides
for saving PSN bandwidth, supports DS0-level grooming and distributed
cross-connect applications. It also enhances resilience of CE devices to
effects of loss of packets in the PSN.

The structured method described in this draft uses a structure locking
mechanism in which there is a constant relationship between a particular
DS0 circuit and the position in which the corresponding information
is carried in the PW payload. The method provides the ability to keep the
edge-to-edge delay of the emulated service independent of the service
rate.

Working Group Summary

Although the Working Group was able to reach consensus on the
unstructured TDM emulation method (SAToP/RFC4553), it could
not reach consensus on the best method of emulating a structured
service. The PWE3 WG therefore decided to pursue two methods as
informational RFCs(draft-ietf-pwe3-cesopsn-07.txt and
draft-ietf-pwe3-tdmoip-05.txt) and to gain operational experience
with the technology before recommending a standards track approach.

Protocol Quality

There are many implementations of this protocol, and it is
in operational service.

Note to RFC Editor

Section 4.4

OLD TEXT

4.4. Usage of the RTP header

When a fixed RTP header (see [RFC3550], Section 5.1) is used with
CESoPSN, its fields are used in the following way:

NEW TEXT

4.4. Usage of the RTP header

Although CESoPSN MAY employ an RTP header when explicit transfer
of timing information is required, this is purely formal reuse of the
header format. RTP mechanisms, such as header extensions, CSRC, list,
padding, RTCP, RTP header compression, SRTP, etc. are not applicable
to CESoPSN pseudowires.

When a fixed RTP header (see [RFC3550], Section 5.1) is used with
CESoPSN, its fields are used in the following way:

END

Section 9 (Security Considerations)

OLD TEXT

Although CESoPSN PWs MAY employ an RTP header when explicit transfer of
timing information is required, SRTP (see [RFC3711]) mechanisms are NOT
RECOMMENDED as a substitute for PW layer security.

NEW TEXT

Although CESoPSN MAY employ an RTP header when explicit transfer
of timing information is required, it is not possible to use
SRTP (see [RFC3711]) mechanisms as a substitute for PW layer
security.

END


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