IETF57 PWE3 Workgroup 16July03 draftvainshteincesopsn06'txt: Summary of Discussion

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IETF-57PWE3 Workgroup 16-July-03
draft-vainshtein-cesopsn-06.txtSummary of
Discussion

• Sasha Vainshtein, Tim Frost, Prayson Pate

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CESoPSN-06 Status (1)

• The CESoPSN draft
• First presented at the 52th IETF meeting
• Evolved
• To cover additional functionality
• To remove unnecessary restrictions
• Fully aligned with the following basic documents
• The WG Charter
• The PWE3 Requirements draft - all the relevant
  requirements covered, non-goals not pursued
• The PWE3 Architecture draft (payload types,
  partitioning between NSP and PW IWF, the
  principle of minimum intervention)
• The TDM PW requirements draft (all the mandatory
  requirements covered)
• RFC 2736 (explicitly referenced in the WG
  Charter)
• The SONET Emulation (CEP) draft

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CESoPSN-06 Status (2)

• The -06 revision of the CESoPSN draft
• A few updates from the -05 version
• Support of trunk-specific Nx64 kbit/s with CAS
  has been defined
• The CW has been fully aligned with CEP
• Request to adopt as a WG item as the basis for
  further WG work posted 06/10/03
• 4 successful interoperability tests have been
  publicly announced
• Prove simplicity and robustness of the proposed
  solution
• Multiple silicon implementations are now
  available, including a high-density solution
• Danny has asked for the WG opinion 06/12/03
• A lively discussion has been maintained on the WG
  mailing list
• A few TECHNICAL issues have been raised by both
  the supporters and the opponents
• Suggested resolutions to these issues are
  presented here

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Unstructured Services

• No conceptual objections raised to the CESoPSN
  for emulation of UNSTRUCTURED services
• A new proposal for unstructured service
  (draft-stein-pwe3-stpp-00)
• Conceptually identical to unstructured mode in
  CESoPSN-06
• See also draft-vainshtein-pwe3-ucesopsn-00.txt
  (presented in Atlanta and incorporated into
  CESoPSN-05/06)
• The following minor differences found
• No option to use RTP
• Different control word format
• Different default payload length/latency for E1
• No showstoppers!

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Specific Technical Issues - 1

• Issue Non-ECMP-compliant CW
• The CESoPSN CW is fully aligned with that of CEP
• It is technically possible to use a standard CW
• Sufficient Flags space (4 flags needed)
• Sufficient Sequence Number space
• Use Fragmentation bits for splitting basic
  structures of trunk-specific Nx64 kbit/s with
  CAS (as per draft-ietf-pwe3-fragmentation-02)
• Alignment with CEP has certain advantages
• Suggested resolution follow the WG input
• 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
• -----------------------
  ---------
• 0000RDNPBE Reserved Sequence
  Number
• -----------------------
  ---------
• An ECMP-compliant
  CESoPSN CW

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Specific Technical Issues - 2

• Issue Usage of RTP header
• Claims made on the PWE3 list
• RTP does not provide any advantages for clock
  recovery with emulated TDM
• G.823 / G.824-compliant clock recovery is
  impossible with TDM emulated over PSN, because IP
  and MPLS do not provide clock at their physical
  layer
• Contention RTP can facilitate G.823/G.824-complia
  nt clock recovery when a common clock source is
  available at both PEs terminating the TDM PW
• The common clock can be provided using BITS, GPS
  etc. (same as with CEP-EPAR)
• The timestamps are generated in accordance with
  this clock (differential mode)
• Suggested resolution
• Preserve the OPTION to use RTP header
• Follow the WG input regarding the default mode

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Specific Technical Issues - 3

• Issue Default packet latency for unstructured E1
• The draft proposes 1 ms
• An alternative proposal 0.5 ms
• Suggested resolution follow the WG input
• Issue Frame alignment for unstructured services
• The draft does NOT require or imply that
• Suggested resolution editorial (explicitly state
  in the text)
• Issue T1-SF Nx64 kbit/s w/CAS
• Basic structure for trunk-specific Nx64 kbit/s
  with CAS defined as the trunk multiframe
• De-facto basic structure used with T1-SF a pair
  of consecutive multiframes
• Suggested resolution editorial (update the
  corresponding portions of the text)

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Questions?