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IETF-58 PWE3 Working Group Structure-Agnostic TDM over Packet draft-ietf-pwe3-satop-00.txt Summary and Open Issues PowerPoint Presentation
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IETF-58 PWE3 Working Group Structure-Agnostic TDM over Packet draft-ietf-pwe3-satop-00.txt Summary and Open Issues. Sasha Vainshtein, Yaakov Stein. 4 months ago in Vienna…. From the PWE3 Session Minutes: Yaakov Stein and Sasha Vainshtein to produce a joint unstructured draft by 1st September

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IETF-58PWE3 Working GroupStructure-Agnostic TDM over Packetdraft-ietf-pwe3-satop-00.txtSummary and Open Issues

Sasha Vainshtein, Yaakov Stein

IETF-58 Minneapolis

4 months ago in vienna
4 months ago in Vienna…
  • From the PWE3 Session Minutes:
    • Yaakov Stein and Sasha Vainshtein to produce a joint unstructured draft by 1st September
    • Yaakov Stein and Sasha Vainshtein invited to re-present their structured work as individual drafts
  • This decision resulted in:

IETF-58 Minneapolis

satop 00
SAToP-00
  • A common draft co-edited by Yaakov and Sasha
    • A new term - "struture-agnostic" coined to reflect the essence
    • Co-authors:
      • Motti Anavi, Tim Frost, Eduard Metz, Prayson Pate, Akiva Sadovski, Israel Sasson, Ronen Shashoua
  • Posted as an individual submission on 04-Sep-03
  • Multiple positive responses on the list
    • Some issues raised during the discussion
  • Adopted as a WG item 23-Sep-03
    • Open issues listed in the re-submitted text
    • WG input solicited for their resolution

IETF-58 Minneapolis

satop 00 2
SAToP-00 (2)
  • Supports E1/T1/E3/T3 TDM bit-streams
    • Fixed-size chunks of the TDM bit stream packetized
      • Default packet size specified per service
      • Any packet size can be used if agreed upon
  • A control word is mandatory:
    • The generic PWE3 CW is used
    • Sequence number follows the RTP rules:
      • Circular 16-bit space without any gaps
    • Two flags:
      • L - forward indication of the local AC failure
        • Payload MAY be omitted
      • R - backward indication of PSN failure

IETF-58 Minneapolis

satop 00 3
SAToP-00 (3)
  • RTP header can be optionally used
    • Positioned differently for IP and MPLS PSN:
      • IP: immediately PRECEDES the CW to resemble the classic RTP
      • MPLS: immediately FOLLOWS the CW to be ECMP-safe
    • Same sequence number used in both the CW and RTP header
    • Two modes of time-stamping:
      • Absolute - the time-stamping clock is the line clock of the local AC
      • Differential - the time-stamping clock is a high-quality clock available at both ends of the PW

IETF-58 Minneapolis

issue octet aligned t1
Issue: "Octet-Aligned T1"
  • Raised by Ron Cohen and Yaron Raz
    • Modern NSPs often extract (unstructured!) T1 mapped to 25 timeslots within a (structured) E1
      • The mapping is defined in ITU-T G.802 (Annex B)
      • Relevant NSPs: SONET/SDH mappers etc.
    • Integration with SAToP is problematic:
      • Carrying an entire E1 using SAToP is BW-expensive
      • De-mapping T1 from E1 requires additional HW
    • Proposals (WG input is solicited):
      • Add a special mode in SAToP?
      • Define a new "octet-aligned T1" service?
      • What else?

IETF-58 Minneapolis

issue t3 ais
Issue: "T3 AIS"
  • Raised by Alex Conta:
    • T3 AIS cannot be detected/generated in a structure-agnostic way:
      • Requires T3 framing
      • No such problem with the rest of the services (E1, T1, E3)
    • AIS is important for SAToP:
      • Detection allows BW saving
      • Generation is desirable in case of AC and PSN failures
        • The current solution ("all ones") indicates a problem but not the specific problem
    • Proposal (WG input is solicited):
      • Direct indication of TDM validity!

IETF-58 Minneapolis

issue a reference to the ef phb
Issue: "A reference to the EF PHB"
  • Raised by the Editors
    • Using EF PHB in SAToP PWs seems natural
      • E.g., see draft-baker-basic-diffserv-classes
      • Appropriate limitations can be explicitly defined
    • The DiffServ WG co-chairs objected to naming any specific PHB in the QoS section of TDM drafts
      • This authoritative ruling has been accepted
      • The doubts remain
    • The WG input and the ADs guidance are solicited
      • The DiffServ WG has concluded

IETF-58 Minneapolis

what remains to be done
What Remains to Be Done
  • Resolve the open issues
  • Allocate the service type code points for the SAToP-supported services
  • Provide a SAToP MIB
    • Will be done in a dedicated draft
  • Add RTP-specific parameters to the PWE3 control protocols
    • Will be done as:
      • A single dedicated draft in this WG?
      • Two control protocol-specific drafts in different WGs?
  • Go to the WG Last Call before the next IETF

IETF-58 Minneapolis

questions
Questions?

IETF-58 Minneapolis