One-Way and Two-Way Active Measurement Protocol Extensions for Performance Measurement on a Link Aggregation Group

One-Way and Two-Way Active Measurement Protocol Extensions for Performance Measurement on a Link Aggregation Group China Mobile

No. 29 Finance Avenue Xicheng District Beijing


          China


        li_zhenqiang@hotmail.com


    
      Huawei
      
        
          China
        
        zhoutianran@huawei.com
      
    
    
      ZTE Corp.
      
        
          China
        
        
        guo.jun2@zte.com.cn
        
      
    
    
      Ericsson
      
        
          
          United States of America
        
        gregimirsky@gmail.com
      
    
    
      Cisco Systems, Inc.
      
        
          Canada
        
        
        rgandhi@cisco.com
        
      
    
    
    Transport Area
    IPPM
    
      This document defines extensions to the One-Way Active Measurement
      Protocol (OWAMP) and the Two-Way Active Measurement Protocol (TWAMP) to
      implement performance measurement on every member link of a Link
      Aggregation Group (LAG). Knowing the measured metrics of each member
      link of a LAG enables operators to enforce the performance-based traffic
      steering policy across the member links.
    
    
      
        Status of This Memo
        
            This is an Internet Standards Track document.
        
        
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by
            the Internet Engineering Steering Group (IESG).  Further
            information on Internet Standards is available in Section 2 of 
            RFC 7841.
        
        
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
            .
        
      
      
        Copyright Notice
        
            Copyright (c) 2024 IETF Trust and the persons identified as the
            document authors. All rights reserved.
        
        
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            () in effect on the date of
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        Table of Contents
        
          
            .  Introduction
            
              
                .  Requirements Language
              
            
          
          
            .  Micro Sessions on a LAG
          
          
            .  Micro OWAMP Session
            
              
                .  Micro OWAMP-Control
              
              
                .  Micro OWAMP-Test
              
            
          
          
            .  Micro TWAMP Session
            
              
                .  Micro TWAMP-Control
              
              
                .  Micro TWAMP-Test
                
                  
                    .  Sender Packet Format and Content
                  
                  
                    .  Sender Behavior
                  
                  
                    .  Reflector Packet Format and Content
                  
                  
                    .  Reflector Behavior
                  
                
              
            
          
          
            .  Applicability
          
          
            .  IANA Considerations
            
              
                .  Micro OWAMP-Control Command
              
              
                .  Micro TWAMP-Control Command
              
            
          
          
            .  Security Considerations
          
          
            .  References
            
              
                .  Normative References
              
              
                .  Informative References
              
            
          
          
            Acknowledgements
          
          
            Authors' Addresses


  
    
      Introduction
      A Link Aggregation Group (LAG), as defined in , provides mechanisms to combine multiple physical
      links into a single logical link. This logical link offers higher
      bandwidth and better resiliency because, if one of the physical member
      links fails, the aggregate logical link can continue to forward traffic
      over the remaining operational physical member links.
      Usually, when forwarding traffic over a LAG, a hash-based mechanism is
      used to load balance the traffic across the LAG member links. The link
      delay might vary between member links because of different transport
      paths, especially when a LAG is used in a wide area network. To provide low-latency service for time-sensitive traffic, we need to explicitly steer
      the traffic across the LAG member links based on the link delay, loss,
      and so on. That requires a solution to measure the performance metrics
      of every member link of a LAG. Hence, the measured performance metrics
      can work together with Layer 2 bundle member link
      attributes advertisement  for traffic steering.
      According to the classifications in , OWAMP  and TWAMP 
      are active measurement methods, and they can complement passive and
      hybrid methods.  With either method, one test session over the LAG can be used to measure the performance of a member link using a specially constructed 5-tuple. The session can be used to measure an average of some or all member links of the LAG by varying one or more elements of that 5-tuple.  However, without the knowledge of each member link, a
      test session cannot measure the performance of every physical member
      link.
      This document extends OWAMP and TWAMP to implement performance
      measurement on every member link of a LAG. It can provide the same
      metrics as OWAMP and TWAMP can measure, such as delay, jitter, and packet
      loss.
      
        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   when, and only when, they appear in all capitals, as
    shown here.
        
      
    
    
      Micro Sessions on a LAG
      This document addresses the scenario where a LAG directly connects
      two nodes. An example of this is in , where the LAG consisting
      of four links connects nodes A and B. The goal is to measure the
      performance of each link of the LAG.
      
        Performance Measurement on a LAG
                          +---+                       +---+
                  |   |-----------------------|   | 
                  | A |-----------------------| B | 
                  |   |-----------------------|   |
                  |   |-----------------------|   |
                  +---+                       +---+ 

      
      To measure the performance metrics of every member link of a LAG,
      multiple sessions (one session for each member link) need to be
      established between the two endpoints that are connected by the LAG.
      These sessions are called "micro sessions" in the remainder of this
      document. Although micro sessions are in fact OWAMP or TWAMP sessions
      established on member links of a LAG, test packets of micro TWAMP
      sessions MUST carry member link information for validation.
      All micro sessions of a LAG share the same Sender IP Address and
      Receiver IP Address. As for the UDP port, the micro sessions
      may share the same Sender Port and Receiver Port pair or each micro
      session may be configured with a different Sender Port and Receiver Port
      pair. From the operational point of view, the former is simpler and
      is RECOMMENDED.
      Test packets of a micro session MUST carry the member link
      information for validation checks. For example, when a micro TWAMP
      Session-Sender receives a reflected test packet, it checks whether the
      test packet is from the expected member link.
    
    
      Micro OWAMP Session
      
        Micro OWAMP-Control
        To support the micro OWAMP session, a new command,
        Request-OW-Micro-Sessions (5), is defined in this document. The
        Request-OW-Micro-Sessions command is based on the OWAMP
        Request-Session command and uses the message format as described in
        . Test session
        creation of micro OWAMP sessions follows the same procedure as defined
        in  with the
        following additions:
        When an OWAMP Server receives a Request-OW-Micro-Sessions command,
        if the request is accepted, the OWAMP Server MUST build a set of micro
        sessions for all the member links of the LAG from which the
        Request-OW-Micro-Sessions message is received.
      
      
        Micro OWAMP-Test
        Micro OWAMP-Test reuses the OWAMP-Test packet format and procedures
        as defined in  with
        the following additions:
        The micro OWAMP Session-Sender MUST send the micro OWAMP-Test
        packets over the member link with which the session is associated.
        When it receives a test packet, the micro OWAMP Session-Receiver MUST
        use the member link from which the test packet is received to
        correlate the micro OWAMP session. If there is no such session, the
        test packet MUST be discarded.
      
    
    
      Micro TWAMP Session
      
        Micro TWAMP-Control
        To support the micro TWAMP session, a new command,
        Request-TW-Micro-Sessions (11), is defined in this document. The
        Request-TW-Micro-Sessions command is based on the TWAMP
        Request-Session command and uses the message format as described in
        . Test session
        creation of micro TWAMP sessions follows the same procedure as defined
        in  with the
        following additions:
        When a TWAMP Server receives a Request-TW-Micro-Sessions command,
        if the request is accepted, the TWAMP Server MUST build a set of micro
        sessions for all the member links of the LAG from which the
        Request-TW-Micro-Sessions message is received.
      
      
        Micro TWAMP-Test
        The micro TWAMP-Test protocol is based on the TWAMP-Test protocol
         with the extensions described in the following subsections.
        
          Sender Packet Format and Content
          The micro TWAMP Session-Sender packet format is based on the
          TWAMP Session-Sender packet format as defined in 
          . Two new fields (Sender Micro-session ID
          and Reflector Micro-session ID) are added to carry the LAG member
          link identifiers.
          For unauthenticated mode, the format is as below:
          
            Micro Session-Sender Packet Format in Unauthenticated Mode
                  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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Sequence Number                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Timestamp                            |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Error Estimate         |             MBZ               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Sender Micro-session ID    |   Reflector Micro-session ID  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                         Packet Padding                        .
     .                                                               .
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          
          For authenticated and encrypted mode, the format is as below:
          
            Micro Session-Sender Packet Format in Authenticated Mode
                  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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Sequence Number                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                        MBZ (12 octets)                        |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          Timestamp                            |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Error Estimate         |              MBZ              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Sender Micro-session ID    |   Reflector Micro-session ID  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                       HMAC (16 octets)                        |
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                        Packet Padding                         .
     .                                                               .
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          
          Except for the Sender Micro-session ID field and the Reflector Micro-session ID field, all the
          other fields are the same as defined in  and follow the procedure and guidelines defined therein.
          
            Sender Micro-session ID (2 octets in length):
            This field is  defined to carry the LAG member link identifier of the Sender
              side. In the future, it may be used generically to cover
              use cases beyond LAGs. The value of this field MUST be unique
              within a TWAMP session at the Session-Sender.
            Reflector Micro-session ID (2 octets in length):
            This field is 
              defined to carry the LAG member link identifier of the Reflector
              side. In the future, it may be used generically to cover
              use cases beyond LAGs. The value of this field MUST be unique
              within a TWAMP session at the Session-Reflector.
          
        
        
          Sender Behavior
          The micro TWAMP Session-Sender inherits the behaviors of the
          TWAMP Session-Sender as defined in . In addition, the micro TWAMP Session-Sender MUST
          send the micro Session-Sender test packets over the member link with
          which the session is associated.
          When sending the test packet, the micro TWAMP Session-Sender MUST
          put the Sender member link identifier that is associated with the
          micro TWAMP session in the Sender Micro-session ID. If the
          Session-Sender knows the Reflector member link identifier, the
          Reflector Micro-session ID field (see Figures 
          and ) MUST be set. Otherwise, the
          Reflector Micro-session ID field MUST be zero.
          A test packet with a Sender member link identifier is sent to the
          Session-Reflector and then is reflected with the same Sender member
          link identifier. So the Session-Sender can use the Sender member
          link identifier to check whether a reflected test packet is received
          from the member link associated with the correct micro TWAMP
          session.
          The Reflector member link identifier carried in the Reflector
          Micro-session ID field is used by the Session-Reflector to check
          whether a test packet is received from the member link associated
          with the correct micro TWAMP session. It means that the
          Session-Sender has to learn the Reflector member link identifier.
          Once the Session-Sender knows the Reflector member link identifier,
          it MUST put the identifier in the Reflector Micro-session ID field
          (see Figures  or )
          of the test packets that will be sent to the Session-Reflector. The
          Reflector member link identifier can be obtained from
          preconfiguration or learned from the data plane (e.g., the
          reflected test packet). This document does not specify the way to
          obtain the Reflector member link identifier.
          When receiving a reflected test packet, the micro TWAMP
          Session-Sender MUST use the receiving member link to correlate the
          reflected test packet to a micro TWAMP session. If there is no such
          session, the reflected test packet MUST be discarded. If a matched
          session exists, the micro Session-Sender MUST use the Sender
          Micro-session ID to validate whether the reflected test packet is
          correctly received from the expected member link. If the validation
          fails, the test packet MUST be discarded. The micro Session-Sender
          MUST use the Reflector Micro-session ID to validate the Reflector's
          behavior. If the validation fails, the test packet MUST be
          discarded.
        
        
          Reflector Packet Format and Content
          The micro TWAMP Session-Reflector packet format is based on the
          TWAMP Session-Reflector packet format as defined in 
          . Two new fields (Sender and Reflector
          Micro-session ID) are added to carry the LAG member link
          identifiers.
          For unauthenticated mode, the format is as below:
          
            Micro Session-Reflector Packet Format in Unauthenticated Mode
            
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sequence Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Timestamp                            |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Error Estimate        |               MBZ             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Receive Timestamp                       |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Sender Sequence Number                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sender Timestamp                        |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Sender Error Estimate    |    Sender Micro-session ID    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Sender TTL   |      MBZ      |   Reflector Micro-session ID  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                                                               .
   .                         Packet Padding                        .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          
          For authenticated and encrypted mode, the format is as below:
          
            Micro Session-Reflector Packet Format in Authenticated Mode
            

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sequence Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        MBZ (12 octets)                        |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Timestamp                            |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Error Estimate        |               MBZ             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Sender Micro-session ID    |   Reflector Micro-session ID  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Receive Timestamp                      |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        MBZ (8 octets)                         |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sender Sequence Number                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        MBZ (12 octets)                        |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Sender Timestamp                         |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Sender Error Estimate    |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                        MBZ (6 octets)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Sender TTL   |                                               |
   +-+-+-+-+-+-+-+-+                                               +
   |                                                               |
   |                                                               |
   |                        MBZ (15 octets)                        |
   +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   |                        HMAC (16 octets)                       |
   |                                                               |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                         Packet Padding                        .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          
          Except for the Sender Micro-session ID field and the Reflector Micro-session ID field, all the
          other fields are the same as defined in  and follow the same procedure and guidelines defined therein.
          
            Sender Micro-session ID (2 octets in length):
            This field is 
              defined to carry the LAG member link identifier of the Sender
              side. In the future, it may be used generically to cover
              use cases beyond LAGs. The value of this field MUST be unique
              within a TWAMP session at the Session-Sender.
            Reflector Micro-session ID (2 octets in length):
            This field is 
              defined to carry the LAG member link identifier of the Reflector
              side. In the future, it may be used generically to cover
              use cases beyond LAGs. The value of this field MUST be unique
              within a TWAMP session at the Session-Reflector.
          
        
        
          Reflector Behavior
          The micro TWAMP Session-Reflector inherits the behaviors of a
          TWAMP Session-Reflector as defined in .
          In addition, when receiving a test packet, the micro TWAMP
          Session-Reflector MUST use the receiving member link to correlate
          the test packet to a micro TWAMP session. If there is no such a
          session, the test packet MUST be discarded. If the Reflector
          Micro-session ID is not zero, the Reflector MUST use the Reflector
          Micro-session ID to validate whether it associates with the
          receiving member link. If the Reflector Micro-session ID is zero, it
          will not be verified. If the validation fails, the test packet MUST
          be discarded.
          When sending a response to the received test packet, the micro
          TWAMP Session-Reflector MUST copy the Sender member link identifier
          from the received test packet and put it in the Sender Micro-session
          ID field of the reflected test packet (see Figures  and ). In
          addition, the micro TWAMP Session-Reflector MUST fill the Reflector
          Micro-session ID field (see Figures  and
          ) of the reflected test packet with
          the member link identifier that is associated with the micro TWAMP
          session.
        
      
    
    
      Applicability
      To set up the micro OWAMP sessions, the Control-Client sends
      the Request-OW-Micro-Sessions command to the OWAMP Server. The OWAMP
      Server accepts the request and builds a set of micro sessions for all
      the member links of the LAG.
      For micro TWAMP sessions, a similar set up procedure is used. Then, the micro TWAMP Session-Sender sends micro
      Session-Sender packets with the Sender Micro-session ID and the
      Reflector Micro-session ID. If the Reflector Micro-session ID field is set, the micro Session-Reflector checks whether a
      test packet is received from the member link associated with the correct
      micro TWAMP session.
      When reflecting, the micro TWAMP Session-Reflector copies the Sender
      Micro-session ID from the received micro Session-Sender packet to the
      micro Session-Reflector packet; then, it sets the Reflector Micro-session ID
      field with the member link identifier that is associated with the micro
      TWAMP session. When receiving the micro TWAMP Session-Reflector packet,
      the micro Session-Sender uses the Sender Micro-session ID to check
      whether the packet is received from the member link associated with the
      correct micro TWAMP session. The micro Session-Sender also uses the
      Reflector Micro-session ID to validate the Reflector's behavior.
    
    
      IANA Considerations
      
        Micro OWAMP-Control Command
        IANA has allocated the following command
        type from the "OWAMP-Control Command Numbers" registry.
        Request-OW-Micro-Sessions Command Number
          
          
            
              Value
              Description
              Reference
            
          
          
            
              5
              Request-OW-Micro-Sessions
              This document
            
          
        
      
      
        Micro TWAMP-Control Command
        IANA has allocated the following command
        type from the "TWAMP-Control Command Numbers" registry.
        Request-TW-Micro-Sessions Command Number
          
          
            
              Value
              Description
              Reference
            
          
          
            
              11
              Request-TW-Micro-Sessions
              This document
            
          
        
      
    
    
      Security Considerations
      This document does not introduce additional security requirements and
      mechanisms other than those described in  and
      .
    
  
  
    
      References
      
        Normative References
        
          
            Key words for use in RFCs to Indicate Requirement Levels
            
            
            
              In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
            
          
          
          
          
        
        
          
            A One-way Active Measurement Protocol (OWAMP)
            
            
            
            
            
            
            
              The One-Way Active Measurement Protocol (OWAMP) measures unidirectional characteristics such as one-way delay and one-way loss. High-precision measurement of these one-way IP performance metrics became possible with wider availability of good time sources (such as GPS and CDMA). OWAMP enables the interoperability of these measurements. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            A Two-Way Active Measurement Protocol (TWAMP)
            
            
            
            
            
            
            
              The One-way Active Measurement Protocol (OWAMP), specified in RFC 4656, provides a common protocol for measuring one-way metrics between network devices. OWAMP can be used bi-directionally to measure one-way metrics in both directions between two network elements. However, it does not accommodate round-trip or two-way measurements. This memo specifies a Two-Way Active Measurement Protocol (TWAMP), based on the OWAMP, that adds two-way or round-trip measurement capabilities. The TWAMP measurement architecture is usually comprised of two hosts with specific roles, and this allows for some protocol simplifications, making it an attractive alternative in some circumstances. [STANDARDS-TRACK]
            
          
          
          
        
        
          
            Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words
            
            
            
              RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.
            
          
          
          
          
        
        
          
            Advertising Layer 2 Bundle Member Link Attributes in IS-IS
            
            
            
            
            
            
            
              There are deployments where the Layer 3 interface on which IS-IS operates is a Layer 2 interface bundle. Existing IS-IS advertisements only support advertising link attributes of the Layer 3 interface. If entities external to IS-IS wish to control traffic flows on the individual physical links that comprise the Layer 2 interface bundle, link attribute information about the bundle members is required.
              This document introduces the ability for IS-IS to advertise the link attributes of Layer 2 (L2) Bundle Members.
            
          
          
          
        
      
      
        Informative References
        
          
            IEEE Standard for Local and Metropolitan Area Networks -- Link Aggregation
            
              IEEE
            
            
          
          
          
        
        
          
            Active and Passive Metrics and Methods (with Hybrid Types In-Between)
            
            
            
              This memo provides clear definitions for Active and Passive performance assessment. The construction of Metrics and Methods can be described as either "Active" or "Passive". Some methods may use a subset of both Active and Passive attributes, and we refer to these as "Hybrid Methods". This memo also describes multiple dimensions to help evaluate new methods as they emerge.
            
          
          
          
        
      
    
    
      Acknowledgements
      The authors would like to thank , , ,
      , , , and  for the valuable
      comments to this work.
    
    
      Authors' Addresses
      
        China Mobile
        
          
            No. 29 Finance Avenue
            Xicheng District
            Beijing
            
            China
          
          li_zhenqiang@hotmail.com
        

      
      
        Huawei
        
          
            China
          
          zhoutianran@huawei.com
        
      
      
        ZTE Corp.
        
          
            China
          
          
          guo.jun2@zte.com.cn
          
        
      
      
        Ericsson
        
          
            
            United States of America
          
          gregimirsky@gmail.com
        
      
      
        Cisco Systems, Inc.
        
          
            Canada
          
          
          rgandhi@cisco.com