Encapsulation of Simple TWAMP (STAMP) for Pseudowires in MPLS Networks
draft-gandhi-mpls-stamp-pw-00

Document Type Active Internet-Draft (individual)
Authors Rakesh Gandhi  , Patrice Brissette  , Eddie Leyton 
Last updated 2021-07-12
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MPLS Working Group                                             R. Gandhi
Internet-Draft                                              P. Brissette
Intended status: Standards Track                     Cisco Systems, Inc.
Expires: January 13, 2022                                      E. Leyton
                                                        Verizon Wireless
                                                           July 12, 2021

 Encapsulation of Simple TWAMP (STAMP) for Pseudowires in MPLS Networks
                     draft-gandhi-mpls-stamp-pw-00

Abstract

   Pseudowires (PWs) are used in MPLS networks for various services
   including carrying layer 2 and layer 3 data packets.  This document
   describes the procedure for encapsulation of the Simple Two-Way
   Active Measurement Protocol (STAMP) defined in RFC 8762 and its
   optional extensions defined in RFC 8972 for PWs in MPLS networks.
   The procedure uses PW Generic Associated Channel (G-ACh) to
   encapsulate the STAMP test packets with or without an IP/UDP header.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on January 13, 2022.

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   carefully, as they describe your rights and restrictions with respect

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   to this document.  Code Components extracted from this document must
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     2.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  Reference Topology  . . . . . . . . . . . . . . . . . . .   4
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Session-Sender Test Packet  . . . . . . . . . . . . . . . . .   5
     4.1.  Session-Sender Test Packet with IP/UDP Header . . . . . .   5
     4.2.  Session-Sender Test Packet without IP/UDP Header  . . . .   7
   5.  Session-Reflector Test Packet . . . . . . . . . . . . . . . .   7
     5.1.  Session-Reflector Test Packet with IP/UDP Header  . . . .   8
     5.2.  Session-Reflector Test Packet without IP/UDP Header . . .  10
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   The Simple Two-way Active Measurement Protocol (STAMP) provides
   capabilities for the measurement of various metrics in IP networks
   [RFC8762] without the use of a control channel to pre-signal session
   parameters.  [RFC8972] defines optional extensions for STAMP.

   Pseudowires (PWs) are used in MPLS networks for various services
   including carrying layer 2 and layer 3 data packets [RFC6658].  The
   PWs are bidirectional in nature.  The PWs can be point-to-point or
   point-to-multipoint.  A PW Generic Associated Channel (G-ACh)
   [RFC5586] provides a mechanism to transport Operations,
   Administration, and Maintenance (OAM) and other control messages over
   MPLS data plane.  The G-ACh channel types identify the various OAM
   messages being transported over the channel.

   The STAMP test packets need to be transmitted with the same MPLS
   label stack that is used by the PW traffic to ensure proper
   validation of underlay path taken by the actual PW traffic.  Also,
   the test packets need to follow the same ECMP path taken by the PW
   traffic.  The STAMP test packets may be encapsulated over the PW

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   associated channel with or without an IP/UDP header.  The
   requirements for the encapsulation of the STAMP test packets for the
   PWs in MPLS networks can be summarized as follows:

   o The PW associated channel MUST support STAMP test packets with IP/
   UDP header.

   o The PW associated channel MUST support STAMP test packets without
   IP/UDP header.

   o The Session-Sender test packets MUST follow the same underlay path
   taken by the traffic for the associated PW channel.

   o The Session-Sender test packets MUST follow the same ECMP underlay
   path taken by the traffic for the associated PW channel.

   o The Session-Reflector test packets MAY follow the same reverse
   underlay path taken by Session-Sender test packets.

   o The Session-Reflector test packets MAY follow the same reverse ECMP
   underlay path taken by Session-Sender test packets.

   This document describes the procedure for encapsulation of the STAMP
   defined in [RFC8762] and its optional extensions defined in [RFC8972]
   for point-to-point PWs in MPLS networks.  The procedure uses PW
   Generic Associated Channel (G-ACh) to encapsulate the STAMP test
   packets with or without an IP/UDP header.  The procedure for point-
   to-multipoint PWs will be added in future.

2.  Conventions Used in This Document

2.1.  Requirements Language

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

2.2.  Abbreviations

   ECMP: Equal Cost Multi-Path.

   G-ACh: Generic Associated Channel.

   GAL: G-ACh Label.

   HMAC: Hashed Message Authentication Code.

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   MPLS: Multiprotocol Label Switching.

   OAM: Operations, Administration, and Maintenance.

   PW: Pseudowires.

   SHA: Secure Hash Algorithm.

   STAMP: Simple Two-way Active Measurement Protocol.

   TC: Traffic Class.

2.3.  Reference Topology

   In the Reference Topology shown in Figure 1, there exists a packet
   pseudowire to transport data between LSRs S1 and R1.  The STAMP
   Session-Sender on LSR S1 initiates a Session-Sender test packet and
   the STAMP Session-Reflector on LSR R1 transmits a reply test packet.
   The reply test packet is transmitted to the STAMP Session-Sender on
   the same path (same set of links and nodes) in the reverse direction
   of the path taken towards the Session-Reflector.

                    |<-------- Pseudowire ------->|
                    |                             |
                    |     T1                T2    |
                    |    /                   \    |
                +-------+     Test Packet     +-------+
                |       | - - - - - - - - - ->|       |
                |   S1  |=====================|   R1  |
                |       |<- - - - - - - - - - |       |
                +-------+  Reply Test Packet  +-------+
                         \                   /
                          T4                T3

            STAMP Session-Sender        STAMP Session-Reflector

     T1, T2, T3, T4: Timestamps as described in [RFC8762]

                       Figure 1: Reference Topology

3.  Overview

   The STAMP Session-Sender and Session-Reflector test packets defined
   in [RFC8972] are transmitted over the PWs in MPLS networks.  The base
   STAMP test packets can be encapsulated using IP/UDP header and may
   use Destination UDP port 862 [RFC8762].

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   The STAMP test packets are encapsulated with MPLS header using the
   same label stack as the PW traffic and the PW G-ACh header.  The
   encapsulation allows the STAMP test packets to follow the same path
   as the PW traffic, and provide the same ECMP path selection on the
   intermediate nodes.

   There are two ways in which STAMP test packets may be encapsulated
   over a PW associated channel, either using an IP/UDP header or
   without using an IP/UDP header.

   For encapsulating the STAMP test packets over a PW associated channel
   with an IP/UDP header, IPv4 and IPv6 G-ACh types [RFC4385] are used
   for both Session-Sender and Session-Reflector test packets.  The
   destination UDP port numbers in the Session-Sender and Session-
   Reflector test packets discriminate the test packets.  The IP version
   (IPv4 or IPv6) MUST match the IP version used for signaling for
   dynamically established PWs or MUST be configured for statically
   provisioned PWs.

   For encapsulating the STAMP test packets over a PW associated channel
   without an IP/UDP header, two new G-ACh types are defined in this
   document, one for the Session-Sender test packets and one for the
   Session-Reflector test packets.  The different G-ACh types are
   required for the Session-Sender and Session-Reflector test packets as
   the STAMP test packet formats do not have a way to discriminate them.

   The Time to Live (TTL)/Hop Limit (HL) and Generalized TTL Security
   Mechanism (GTSM) procedures from [RFC5082] apply to this
   encapsulation, and hence the TTL/HL is set to 255.

   The G-ACh label (GAL) [RFC5586] is not added in the MPLS label stack.

4.  Session-Sender Test Packet

4.1.  Session-Sender Test Packet with IP/UDP Header

   The content of an example STAMP Session-Sender test packet
   encapsulated over a PW associated channel using an IP/UDP header is
   shown in Figure 2.  The STAMP G-ACh header [RFC5586] with G-ACh MUST
   immediately follow the bottom of the MPLS label stack.  The payload
   contains the STAMP Session-Sender test packet defined in [RFC8972].

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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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Label(1)               | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                PW Label               | TC  |1|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|    Reserved   | IPv4 (0x0021) or IPv6 (0x0057)|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IP Header                                                     |
    .  Source IP Address = Session-Sender IPv4 or IPv6 Address      .
    .  Destination IP Address=Session-Reflector IPv4 or IPv6 Address.
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Session-Sender                    .
    .  Destination Port = User-configured Destination Port | 862    .
    .                                                               .
    +---------------------------------------------------------------+
    | Payload = Test Packet as specified in Section 3 of RFC 8972   |
    .           in Figure 1 and Figure 3                            .
    .                                                               .
    +---------------------------------------------------------------+
    | Optional STAMP TLVs defined in RFC 8972                       |
    .                                                               .
    +---------------------------------------------------------------+

      Figure 2: Example Session-Sender Test Packet with IP/UDP Header

   The STAMP Session-Sender test packet G-ACh header contains following
   fields:

   Version:  The Version field is set to 0, as defined in [RFC4385].

   Reserved:  Reserved Bits MUST be set to zero upon transmission and
     ignored upon receipt.

   Channel Type:  G-ACh channel type for IPv4 header (0x0021) or IPv6
     header (0x0057) [RFC4385].

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4.2.  Session-Sender Test Packet without IP/UDP Header

   The content of an example STAMP Session-Sender test packet
   encapsulated over a PW associated channel without using an IP/UDP
   header is shown in Figure 3.  The STAMP G-ACh header [RFC5586] with
   new STAMP Session-Sender G-ACh type (value TBD1) MUST immediately
   follow the bottom of the MPLS label stack.  The payload contains the
   STAMP Session-Sender test packet defined in [RFC8972].

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Label(1)               | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                PW Label               | TC  |1|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|    Reserved   | STAMP G-ACh (TBD1)            |
    +---------------------------------------------------------------+
    | Payload = Test Packet as specified in Section 3 of RFC 8972   |
    .           in Figure 1 and Figure 3                            .
    .                                                               .
    +---------------------------------------------------------------+
    | Optional STAMP TLVs defined in RFC 8972                       |
    .                                                               .
    +---------------------------------------------------------------+

    Figure 3: Example Session-Sender Test Packet without IP/UDP Header

   The STAMP Session-Sender test packet G-ACh header contains following
   fields:

   Version:  The Version field is set to 0, as defined in [RFC4385].

   Reserved:  Reserved Bits MUST be set to zero upon transmission and
     ignored upon receipt.

   Channel Type:  G-ACh channel type for STAMP Session-Sender packet
     (TBD1).

5.  Session-Reflector Test Packet

   The STAMP Session-Reflector reply test packet is sent on the same
   path in the reverse direction of a bidirectional PW.  The STAMP test
   packet can be sent using an MPLS header with or without IP/UDP

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   header.  The Session-Reflector test packet is sent with an IP/UDP
   header if the Session-Sender test packet is received with an IP/UDP
   header, otherwise, it is sent without an IP/UDP header.

5.1.  Session-Reflector Test Packet with IP/UDP Header

   The content of an example STAMP Session-Reflector test packet
   encapsulated over a PW associated channel using an IP/UDP header is
   shown in Figure 4.  The STAMP G-ACh header [RFC5586] with G-ACh MUST
   immediately follow the bottom of the MPLS label stack.  The payload
   contains the STAMP Session-Reflector test packet defined in
   [RFC8972].

   The STAMP Session-Reflector reply test packet MUST use the IP/UDP
   information from the received test packet when an IP/UDP header is
   present in the received test packet.

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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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Label(1)               | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                PW Label               | TC  |1|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|    Reserved   | IPv4 (0x0021) or IPv6 (0x0057)|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IP Header                                                     |
    .  Source IP Address = Session-Reflector IPv4 or IPv6 Address   .
    .  Destination IP Address                                       .
    .              = Source IP Address from Received Test Packet    .
    .                                                               .
    +---------------------------------------------------------------+
    | UDP Header                                                    |
    .  Source Port = As chosen by Session-Reflector                 .
    .  Destination Port = Source Port from Received Test Packet     .
    .                                                               .
    +---------------------------------------------------------------+
    | Payload = Test Packet as specified in Section 3 of RFC 8972   |
    .           in Figure 2 and Figure 4                            .
    .                                                               .
    +---------------------------------------------------------------+
    | Optional STAMP TLVs defined in RFC 8972                       |
    .                                                               .
    +---------------------------------------------------------------+

    Figure 4: Example Session-Reflector Test Packet with IP/UDP Header

   The STAMP Session-Reflector test packet G-ACh header contains
   following fields:

   Version:  The Version field is set to 0, as defined in [RFC4385].

   Reserved:  Reserved Bits MUST be set to zero upon transmission and
     ignored upon receipt.

   Channel Type:  G-ACh channel type for IPv4 header (0x0021) or IPv6
     header (0x0057) [RFC4385].

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5.2.  Session-Reflector Test Packet without IP/UDP Header

   The content of an example STAMP Session-Reflector test packet
   encapsulated over a PW associated channel without using an IP/UDP
   header is shown in Figure 5.  The STAMP G-ACh header [RFC5586] with
   new STAMP Session-Reflector G-ACh type (value TBD2) MUST immediately
   follow the bottom of the MPLS label stack.  The payload contains the
   STAMP Session-Reflector test packet defined in [RFC8972].

   The STAMP Session-Reflector reflects the test packet back to the
   Session-Sender using the same channel of the reverse direction of the
   PW on which it was received.  The Session-Reflector has enough
   information to reflect the test packet received by it to the Session-
   Sender using the PW context.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                Label(1)               | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                PW Label               | TC  |1|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|    Reserved   | STAMP G-ACh (TBD2)            |
    +---------------------------------------------------------------+
    | Payload = Test Packet as specified in Section 3 of RFC 8972   |
    .           in Figure 2 and Figure 4                            .
    .                                                               .
    +---------------------------------------------------------------+

   Figure 5: Example Session-Reflector Test Packet without IP/UDP Header

   The STAMP Session-Reflector test packet G-ACh header contains
   following fields:

   Version:  The Version field is set to 0, as defined in [RFC4385].

   Reserved:  Reserved Bits MUST be set to zero upon transmission and
     ignored upon receipt.

   Channel Type:  G-ACh channel type for STAMP Session-Reflector packet
     (TBD2).

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6.  Security Considerations

   The usage of STAMP protocol is intended for deployment in limited
   domains [RFC8799].  As such, it assumes that a node involved in STAMP
   protocol operation has previously verified the integrity of the path
   and the identity of the far-end STAMP Session-Reflector.

   If desired, attacks can be mitigated by performing basic validation
   and sanity checks, at the STAMP Session-Sender, of the counter or
   timestamp fields in received reply test packets.  The minimal state
   associated with these protocols also limits the extent of disruption
   that can be caused by a corrupt or invalid packet to a single test
   cycle.

   Use of HMAC-SHA-256 in the authenticated mode protects the data
   integrity of the test packets.  Cryptographic measures may be
   enhanced by the correct configuration of access-control lists and
   firewalls.

   The security considerations specified in [RFC8762] and [RFC8972] also
   apply to the procedure described in this document.  Specifically, the
   message integrity protection using HMAC, as defined in [RFC8762]
   Section 4.4, also apply to the procedure described in this document.

   Routers that support G-ACh are subject to the same security
   considerations as defined in [RFC4385] and [RFC5586].

7.  IANA Considerations

   IANA maintains G-ACh Type Registry (see
   <https://www.iana.org/assignments/g-ach-parameters/g-ach-
   parameters.xhtml>).  IANA is requested to allocate values for the
   STAMP G-ACh Types from "MPLS Generalized Associated Channel (G-ACh)
   Types (including Pseudowire Associated Channel Types)" registry.

      +-------+------------------------------------+---------------+
      | Value | Description                        | Reference     |
      +-------+------------------------------------+---------------+
      | TBD1  | STAMP Session-Sender G-ACh Type    | This document |
      | TBD2  | STAMP Session-Reflector G-ACh Type | This document |
      +-------+------------------------------------+---------------+

                         Table 1: STAMP G-ACh Type

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8.  References

8.1.  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>.

   [RFC4385]  Bryant, S., Swallow, G., Martini, L., and D. McPherson,
              "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
              Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385,
              February 2006, <https://www.rfc-editor.org/info/rfc4385>.

   [RFC5586]  Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
              "MPLS Generic Associated Channel", RFC 5586,
              DOI 10.17487/RFC5586, June 2009,
              <https://www.rfc-editor.org/info/rfc5586>.

   [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>.

8.2.  Informative References

   [RFC5082]  Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
              Pignataro, "The Generalized TTL Security Mechanism
              (GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
              <https://www.rfc-editor.org/info/rfc5082>.

   [RFC6658]  Bryant, S., Ed., Martini, L., Swallow, G., and A. Malis,
              "Packet Pseudowire Encapsulation over an MPLS PSN",
              RFC 6658, DOI 10.17487/RFC6658, July 2012,
              <https://www.rfc-editor.org/info/rfc6658>.

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   [RFC8799]  Carpenter, B. and B. Liu, "Limited Domains and Internet
              Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,
              <https://www.rfc-editor.org/info/rfc8799>.

Acknowledgments

   TBA.

Authors' Addresses

   Rakesh Gandhi
   Cisco Systems, Inc.
   Canada

   Email: rgandhi@cisco.com

   Patrice Brissette
   Cisco Systems, Inc.
   Canada

   Email: pbrisset@cisco.com

   Edward Leyton
   Verizon Wireless

   Email: edward.leyton@verizonwireless.com

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