IP Performance Measurement                                      G. White
Internet-Draft                                                 CableLabs
Intended status: Standards Track                        10 December 2024
Expires: 13 June 2025


 Simple Two-Way Active Measurement Protocol (STAMP) Extension for DSCP
                     and ECN Traversal Measurement
                     draft-white-ippm-stamp-ecn-00

Abstract

   The Simple Two-Way Active Measurement Protocol (STAMP) enables one-
   way and round-trip measurement of network metrics between IP hosts,
   and has a facility for defining optional extensions.  This document
   defines a STAMP extension to enable the measurement of manipulation
   of the value of the explicit congestion notification (ECN) field of
   the IP header by middleboxes between two STAMP hosts, and to enable
   discovery and measurement of paths that provide differential
   treatment of packets depending on the value of their ECN field.

Status of This Memo

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   This Internet-Draft will expire on 13 June 2025.

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   extracted from this document must include Revised BSD License text as
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  DSCP and ECN Traversal STAMP Extension  . . . . . . . . . . .   2
   3.  Implementation Status . . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Section 4.4 of [RFC8972] defines a "Class of Service TLV" extension
   for the STAMP protocol [RFC8762] which enables bi-directional
   measurement of manipulation of the differentiated services code point
   (DSCP) field of the IP header by middleboxes [RFC2474] but only
   allows one-way measurement of manipulation of the ECN field of the IP
   header by [RFC3168][RFC8311][RFC9331] middleboxes.  Since the ECN
   field of the IP header is separately meaningful in each direction, it
   is valuable to have the capability to perform bi-directional
   measurements of ECN traversal and to have the abilty to measure path
   characteristics that depend on the value of the ECN codepoint.  In
   addition, bi-directional measurements are important to isolate
   traversal issues so that remediation actions can be taken
   appropriately.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  DSCP and ECN Traversal STAMP Extension

   The STAMP session-sender MAY include a DSCP and ECN TLV in the STAMP
   test packet.  The format of the TLV is presented in Figure 1.




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       0                   1                   2                   3
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |STAMP TLV Flags|      Type     |           Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   DSCP1   |EC1|  DSCP2    |EC2| RP|    Reserved               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 1: DSCP and ECN Traversal TLV

   The fields are defined as follows.

   *  STAMP TLV Flags: eight-bit field; format presented in [RFC8972].

   *  Type: one-octet field; value 179 allocated by this specification

   *  Length: two-octet field; set equal to the value 4 octets

   *  DSCP1: DSCP value intended by the session-sender to be used as the
      DSCP value of the reflected test packet

   *  EC1: ECN value intended by the session-sender to be used as the
      ECN value of the reflected test packet

   *  DSCP2: received value in the DSCP field at the ingress of the
      session-reflector

   *  EC2: received value in the ECN field at the ingress of the
      session-reflector

   *  RP (reverse path): two-bit field; a session-sender MUST set the
      value of the RP field to 0 on transmission

   *  Reserved: fourteen-bit field to be zeroed on transmission and
      ignored on receipt

   A session-reflector that receives a test packet with the DSCP and ECN
   Traversal TLV MUST include the DSCP and ECN Traversal TLV in the
   reflected test packet.

   The session-reflector MUST copy the value of the DSCP and ECN fields
   of the IP header of the received STAMP test packet into the DSCP2
   field and EC2 field in the reflected test packet.

   The session-reflector MUST set the value of the ECN field in the IP
   header of the reflected test packet equal to the value in the EC1
   field of the received test packet.




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   Finally, the session-reflector MUST use the local policy to verify
   whether the CoS corresponding to the value of the DSCP1 field is
   permitted in the domain.  If the corresponding CoS is permitted in
   the domain, the session-reflector MUST set the DSCP field's value in
   the IP header of the reflected test packet equal to the value of the
   DSCP1 field of the received test packet.  If the corresponding CoS is
   not permitted in the domain, the session-reflector MUST use the DSCP
   value of the received STAMP packet and set the value of the RP field
   to 1.  Upon receiving the reflected packet, if the value of the RP
   field is 0, the session-sender will save the DSCP and ECN values for
   analysis of the CoS in the reverse direction.  If the value of the RP
   field in the received reflected packet is 1, only CoS in the forward
   direction can be analyzed.

3.  Implementation Status

   The author is aware of two independent implementations of this STAMP
   Extension TLV, one of which is publicly available here
   (https://github.com/cerfcast/teaparty).

4.  IANA Considerations

   Add this extension to the IANA STAMP TLV Types
   (https://www.iana.org/assignments/stamp-tlv-types/stamp-tlv-
   types.xhtml#stamp-tlv-types-1) Registry.

   *  Value = 179

   *  Description = "DSCP and ECN Traversal"

   *  Reference = this document

5.  Security Considerations

   This document should not affect the security of the Internet.

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.







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   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <https://www.rfc-editor.org/info/rfc2474>.

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, DOI 10.17487/RFC3168, September 2001,
              <https://www.rfc-editor.org/info/rfc3168>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8762]  Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
              Two-Way Active Measurement Protocol", RFC 8762,
              DOI 10.17487/RFC8762, March 2020,
              <https://www.rfc-editor.org/info/rfc8762>.

   [RFC8972]  Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A.,
              and E. Ruffini, "Simple Two-Way Active Measurement
              Protocol Optional Extensions", RFC 8972,
              DOI 10.17487/RFC8972, January 2021,
              <https://www.rfc-editor.org/info/rfc8972>.

6.2.  Informative References

   [RFC8311]  Black, D., "Relaxing Restrictions on Explicit Congestion
              Notification (ECN) Experimentation", RFC 8311,
              DOI 10.17487/RFC8311, January 2018,
              <https://www.rfc-editor.org/info/rfc8311>.

   [RFC9331]  De Schepper, K. and B. Briscoe, Ed., "The Explicit
              Congestion Notification (ECN) Protocol for Low Latency,
              Low Loss, and Scalable Throughput (L4S)", RFC 9331,
              DOI 10.17487/RFC9331, January 2023,
              <https://www.rfc-editor.org/info/rfc9331>.

Acknowledgements

   TBD

Contributors

   Karthik Sundaresan, William Hawkins III





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Author's Address

   Greg White
   CableLabs
   858 Coal Creek Circle
   Louisville, Colorado 80027
   United States of America
   Email: g.white@cablelabs.com
   URI:   http://www.cablelabs.com










































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