


Network Working Group                                   Murtaza S. Chiba
Internet-Draft                                           Alexander Clemm
Intended status: Informational                             Steven Medley
Expires: May 18, 2012                                     Joseph Salowey
                                                         Sudhir Thombare
                                                        Eshwar Yedavalli
                                                           Cisco Systems
                                                       November 15, 2011


                 Cisco Service Level Assurance Protocol
                      draft-cisco-sla-protocol-00

Abstract

   Cisco's Service Level Assurance Protocol is a protocol that has been
   widely deployed.  The protocol is used to measure service level
   parameters such as network latency, delay variation, and packet/frame
   loss.  This draft describes the protocol.

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 RFC 2119 [RFC2119].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 18, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Control Phase  . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.1.  Control Request  . . . . . . . . . . . . . . . . . . .  5
         2.1.1.1.  Command Header . . . . . . . . . . . . . . . . . .  6
         2.1.1.2.  CSLDs  . . . . . . . . . . . . . . . . . . . . . .  8
       2.1.2.  Control Response Message . . . . . . . . . . . . . . . 13
     2.2.  Measurement Phase  . . . . . . . . . . . . . . . . . . . . 14
   3.  Implementation notes . . . . . . . . . . . . . . . . . . . . . 18
   4.  Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 19
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 21
     6.1.  Message Authentication . . . . . . . . . . . . . . . . . . 21
     6.2.  IPSec Considerations . . . . . . . . . . . . . . . . . . . 22
       6.2.1.  Control Traffic  . . . . . . . . . . . . . . . . . . . 22
       6.2.2.  Measurement Traffic  . . . . . . . . . . . . . . . . . 22
     6.3.  Replay Protection  . . . . . . . . . . . . . . . . . . . . 23
   7.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . . 23
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 24
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 24
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24















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1.  Introduction

   Network performance measurements are becoming critical data points
   for administrators monitoring the health of the network.  As Service
   Providers look to differentiate their offerings, performance
   measurement is an important tool to monitor Service Level guarantees
   and, in general, is a useful tool for administrators to monitor the
   health of a network.

   Performance metrics can be used for pre-deployment validation as well
   as for measuring in-band live network performance characteristics.
   Cisco's Service Level Assurance Protocol measures both round trip and
   one-way metrics.  It can be used to measure service levels in L2 and
   L3 networks and applications running on top of L3.  The performance
   measurement is achieved by actively generating synthetic test packets
   and sending them across the network, and analyzing those packets and
   packets that are returned in response.  This is in contrast to
   passive measurements that analyze production traffic flowing through
   a particular network element.

   The Cisco Service Level Assurance Protocol has a rich set of
   measurement types that can be classified as those that test
   connectivity (ping like) by providing round trip or, one-way latency
   measures and those that provide a greater variety of statistics
   including network jitter and packet/frame loss.  Each type of active
   measurement simulates an actual protocol exchange.

   The UDP measurement type message exchanges, as covered in this
   document, simulates an UDP application and can be used to simulate
   both Voice and Video traffic that is carried in RTP frames within UDP
   envelopes.  The UDP measurement type message exchanges carry
   information that provide the ability to derive a robust set of
   statistics.


2.  Protocol

   The Cisco Service Level Assurance Protocol consists of two distinct
   phases, the Control Phase and the Measurement Phase.  Each phase is
   comprised of exchange of information between a network element acting
   as the Sender and another element designated as the Responder.

   The Control Phase is the first phase of message exchanges and forms
   the base protocol.  This phase establishes the identity of the Sender
   and provides information for the Measurement Phase.  A single message
   pair of Control Request and Control Response marks this phase.  The
   Sender initiates a Control Request message that is acknowledged by
   the Responder with a Control Response message.  The Control Request



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   may be sent multiple times if a Control Response has not been
   received; the number of times the message is retried is configurable
   on the Sender element.

   The Measurement Phase forms the second phase and is comprised of a
   sequence of Request/Response messages.  These messages may be
   exchanged as often as required.  The number and frequency with which
   messages are sent is controlled by configuration on the Sender
   element.  Each Measurement Request message is acknowledged by the
   Responder with a Measurement Response Message.

   The following sequence diagram depicts the message exchanges:


       +-+-+-+-+-+-+-+      Control Request           +-+-+-+-+-+-+-+
       |             |                                |             |
       |    Sender   |                                |  Responder  |
       |             |                                |             |
       |             |                                |             |
       +-+-+-+-+-+-+-+                                +-+-+-+-+-+-+-+
              |                                              |
              |             Control Request                  |
              | -------------------------------------------->|
              |                                              |
              |             Control Response                 |
              |<---------------------------------------------|
              |                                              |
              |                                              |
              |             Measurement Request(1)           |
              | -------------------------------------------->|
              |                                              |
              |             Measurement Response(1)          |
              |<---------------------------------------------|
              |                                              |
              .                                              .
              .                                              .
              .                                              .
              .                                              .
              .             Measurement Request(n)           .
              | -------------------------------------------->|
              |                                              |
              |             Measurement Response(n)          |
              |<---------------------------------------------|
              |                                              |







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2.1.  Control Phase

   The Control Phase begins with the Sender sending a Control Request
   message to the Responder.  The Control Request message is sent to UDP
   port 1167 on the Responder requesting a measurement phase UDP port be
   opened and indicates the requested amount of time that the port needs
   to be opened for.  The Responder replies by sending a Control
   Response with appropriate Status indicating Success when the sender
   identity is verified (if used) and that the UDP port was successfully
   opened.  In all other cases a non-zero Status is returned.

   The sequence of exchanges is as indicated in the diagram.



       +-+-+-+-+-+-+-+      Control Request           +-+-+-+-+-+-+-+
       |             |------------------------------->|             |
       |    Sender   |                                |  Responder  |
       |             |      Control Response          |             |
       |             |<-------------------------------|             |
       +-+-+-+-+-+-+-+                                +-+-+-+-+-+-+-+

2.1.1.  Control Request

   The Control Request message consists of a Command Header followed by
   one or more Command, Status, Length and Data sections (henceforth
   known as CSLD).  At the minimum, there SHOULD be at the least two
   CSLD sections, one of which is the authentication CSLD section and
   the other carries information for the Measurement Phase simulation
   type.





















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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                                                               +
       |                      Command Header                           |
       +                                                               +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Command                   |           Status              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          Command Length                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       .                                                               .
       .                          Data                                 .
       .                                                               .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Command                   |          Status               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Command Length                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       .                                                               .
       .                          Data                                 .
       .                                                               .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

2.1.1.1.  Command Header

   The Command Header is the first section of the Control Request
   message and is depicted below:













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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Version = 2   |     Reserved  |          Status               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Sequence Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Total Length                          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Send Timestamp                         |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Command Header fields hold the following meaning:

   +-----------+-----------+-------------------------------------------+
   | Field     | Size      | Usage                                     |
   |           | (bits)    |                                           |
   +-----------+-----------+-------------------------------------------+
   | Version   | 8         | Current version supported and is to be    |
   |           |           | set to 2.                                 |
   | --------- | --------- | --------------------------                |
   | Reserved  | 8         | Reserved field, MUST be set to 0          |
   | --------- | --------- | --------------------------                |
   | Status    | 16        | Indicates success or failure for the      |
   |           |           | entire message; not used for request and  |
   |           |           | MUST be set to 0                          |
   | --------- | --------- | --------------------------                |
   | Sequence  | 32        | Used to map requests to responses.  This  |
   | Number    |           | is a monotonically increasing number.     |
   |           |           | Implementations MAY reset the sequence    |
   |           |           | number to 0 after a reboot, and SHOULD    |
   |           |           | wrap around after all bits have been      |
   |           |           | exceeded.                                 |
   | --------- | --------- | --------------------------                |
   | Total     | 32        | Carries the total length of the control   |
   | Length    |           | message in number of octets               |
   | --------- | --------- | --------------------------                |
   | Send      | 64        | This field is set to the time the command |
   | Timestamp |           | was sent and is updated for a response.   |
   |           |           | This field MAY be used for secure         |
   |           |           | environment.  SHOULD be updated for a     |
   |           |           | response.  When not being used it MUST be |
   |           |           | set to all 0's.  The format is as given   |
   |           |           | in RFC1305                                |
   +-----------+-----------+-------------------------------------------+




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   The sequence number field MUST include a new number for each new
   request and is monotonically increasing.  When the Control Request is
   to be retried, the sequence number MUST remain unchanged.

2.1.1.2.  CSLDs

   The two CSLDs to be included, in order, along with the Command Header
   are:

   o  The Authentication CSLD

   o  A Measurement Type CSLD

   In this revision of the protocol, only a single Measurement Type CSLD
   has been defined, the UDP Measurement Type CSLD.  For future
   extensions it is possible to add additional Measurement Type CSLDs.
   For more details please see the section on Extensions.

2.1.1.2.1.  Authentication CSLD

   The Authentication CSLD provides the message authentication and
   verifies the requester knows the shared-secret.  The following is the
   format for the Authentication CSLD




























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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Command = 1         |            Status             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Command Length                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Mode      |   Reserved    |          Key Id               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                  Random Number                                +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                                                               +
       |                                                               |
       .                                                               .
       .                                                               .
       .                  Message Authentication Digest                .
       .                                                               .
       .                                                               .
       |                                                               |
       +                                                               +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields for the Authentication CSLD have the following meaning
















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   +----------------+-----------+--------------------------------------+
   | Field          | Size      | Description                          |
   |                | (bits)    |                                      |
   +----------------+-----------+--------------------------------------+
   | Command        | 16        | Indicates the CSLD is of type        |
   |                |           | Authentication                       |
   | ---------      | --------- | --------------------------           |
   | Status         | 16        | Not used for a request and MUST be   |
   |                |           | set to 0                             |
   | ---------      | --------- | --------------------------           |
   | Command Length | 16        | Indicates the length of the CSLD     |
   | ---------      | --------- | --------------------------           |
   | Mode           | 8         | Indicates the type of authentication |
   |                |           | being used and is set as follows: 0  |
   |                |           | - No Authentication, 1 - SHA256      |
   |                |           | Authentication, 2 - HMAC-SHA-256     |
   | ---------      | --------- | --------------------------           |
   | Reserved       | 8         | This field is reserved for future    |
   |                |           | extensions and MUST be set to 0      |
   | ---------      | --------- | --------------------------           |
   | Key ID         | 16        | Indicates the index number of the    |
   |                |           | shared-secret to be used for         |
   |                |           | authenticating the Control Request   |
   |                |           | Message                              |
   | ---------      | --------- | --------------------------           |
   | Random Number  | 128       | This field is to be unique over the  |
   |                |           | shared secret life and is used to    |
   |                |           | make it difficult to predict the     |
   |                |           | shared secret via multiple packet    |
   |                |           | captures.  The value is reflected in |
   |                |           | a response message.  This field MAY  |
   |                |           | be used in a more secure             |
   |                |           | environments.  When not being used   |
   |                |           | it should be set to all 0's          |
   | ---------      | --------- | --------------------------           |
   | Message        | 256       | Contains the message authentication  |
   | Authentication |           | digest and is computed over the      |
   | Digest         |           | entire control packet including this |
   |                |           | field set to all 0s                  |
   +----------------+-----------+--------------------------------------+

2.1.1.2.2.  UDP Measurement CSLD

   The UDP Measurement CSLD indicates the Measurement Type to be used
   during the Measurement Phase and specifies the addresses and UDP port
   to be opened as well as the duration the port has to be kept open for
   the measurement phase.  The format of the CSLD is as follows:




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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Command = 2         |            Status             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                       Command length                          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Address Type  |     Role      |          Reserved             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                       Session Identifier                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                  Control Source Address                       |
       +                                                               +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                                                               +
       |                  Control Destination Address                  |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                                                               +
       |                  Measurement Source Address                   |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                                                               +
       |                  Measurement Destination Address              |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Control Source Port          |          Reserved             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Measurement Source Port      | Measurement Destination Port  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Duration                              |



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       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields in the UDP Measurement CSLD have the following meaning:

   +-------------+-----------+-----------------------------------------+
   | Field       | Size      | Definition                              |
   |             | (bits)    |                                         |
   +-------------+-----------+-----------------------------------------+
   | Command     | 16        | Indicates that the CSLD is to simulate  |
   |             |           | UDP traffic measurements.               |
   | ---------   | --------- | --------------------------              |
   | Status      | 16        | Not used for a request and MUST be set  |
   |             |           | to 0                                    |
   | ---------   | --------- | --------------------------              |
   | Command     | 32        | Indicates the length of the CSLD        |
   | Length      |           |                                         |
   | ---------   | --------- | --------------------------              |
   | Address     | 8         | Indicates the address type and is set   |
   | Type        |           | to one of the values in the Cisco       |
   |             |           | Service Level Performance Measurement   |
   |             |           | Protocol - Address Registry. (1 - IPv4  |
   |             |           | addresses, 2 - IPv6 addresses)          |
   | ---------   | --------- | --------------------------              |
   | Role        | 8         | Indicates the role of the endpoint      |
   |             |           | receiving the control message and is    |
   |             |           | set as follows: 1 - Responder           |
   | ---------   | --------- | --------------------------              |
   | Reserved    | 16        | Reserved and MUST be set to 0           |
   | ---------   | --------- | --------------------------              |
   | Session     | 32        | Carries a session identifier that is a  |
   | Identifier  |           | locally significant unique value to the |
   |             |           | originator of the message.  MUST be 0   |
   |             |           | when not specified.                     |
   | ---------   | --------- | --------------------------              |
   | Control     | 128       | Set to the address from which the       |
   | Source      |           | Sender initiates control messages.  For |
   | Address     |           | IPv4 addresses only the first 32 bits   |
   |             |           | are filled and the remaining bits MUST  |
   |             |           | be set to 0                             |
   | ---------   | --------- | --------------------------              |
   | Control     | 128       | Set to the address on the Responder     |
   | Destination |           | where the control message will be sent. |
   | Address     |           | For IPv4 addresses only the first 32    |
   |             |           | bits are filled and the remaining bits  |
   |             |           | MUST be set to 0                        |
   | ---------   | --------- | --------------------------              |





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   | Measurement | 128       | Set to the address of the Sender from   |
   | Source      |           | where the measurement packets will      |
   | Address     |           | originate.  For IPv4 addresses only the |
   |             |           | first 32 bits are filled and the        |
   |             |           | remaining bits MUST be set to 0         |
   | ---------   | --------- | --------------------------              |
   | Measurement | 128       | Set to the address on the Responder     |
   | Destination |           | towards which the measurement packets   |
   | Address     |           | will be sent and is a way to identify   |
   |             |           | an ingress interface on the Responder.  |
   |             |           | For IPv4 addresses only the first 32    |
   |             |           | bits are filled and the remaining bits  |
   |             |           | MUST be set to 0                        |
   | ---------   | --------- | --------------------------              |
   | Control     | 16        | Indicates the port on the Sender from   |
   | Source Port |           | which Control message is sent.  If      |
   |             |           | unset the value should be derived from  |
   |             |           | the incoming packet.                    |
   | ---------   | --------- | --------------------------              |
   | Reserved    | 16        | Reserved Field, MUST be set to 0.       |
   | ---------   | --------- | --------------------------              |
   | Measurement | 16        | Indicates the UDP Port on the Sender    |
   | Source Port |           | from which the measurement packets will |
   |             |           | be sent                                 |
   | ---------   | --------- | --------------------------              |
   | Measurement | 16        | Indicates the UDP Port on the Responder |
   | Destination |           | towards which the measurement packets   |
   | Port        |           | will be sent                            |
   | ---------   | --------- | --------------------------              |
   | Duration    | 32        | This is the duration in seconds the     |
   |             |           | port needs to be kept open for          |
   |             |           | accepting measurement phase messages.   |
   |             |           | Measurement messages received after the |
   |             |           | duration MUST be ignored                |
   +-------------+-----------+-----------------------------------------+

2.1.2.  Control Response Message

   In response to the Control Request Message the network element
   designated the Responder sends back a Control Response Message that
   reflects the Command Header with an updated Status field and includes
   the two CSLD sections that also carry updated Status fields.  Hence,
   the format is identical to the Control Request message as described
   above.

   Following table shows the supported values of the Status fields:





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   +-----------+-------------------------------------------------------+
   | Status    | Description                                           |
   | Value     |                                                       |
   +-----------+-------------------------------------------------------+
   | 0         | Success                                               |
   | --------- | --------------------------                            |
   | 1         | Fail - catch all                                      |
   | --------- | --------------------------                            |
   | 2         | Authentication Failure                                |
   | --------- | --------------------------                            |
   | 3         | Format error - sent when any CSLD type is not         |
   |           | recognized or any part of a CSLD has a value that is  |
   |           | not recognized                                        |
   | --------- | --------------------------                            |
   | 4         | Port in use - the UDP/TCP port is already being used  |
   |           | by some other application and cannot be reserved      |
   | --------- | --------------------------                            |
   | 5+        | Future extension and experimental values, please      |
   |           | refer to Status Types Registry in the IANA            |
   |           | Considerations section                                |
   +-----------+-------------------------------------------------------+

   The Command Header Status indicates Success only if all the CSLD
   sections have Status as Success.  It is non-zero otherwise.  Future
   extensions MAY extend these values as appropriate.

   The Control Response message, besides the update of the Status
   fields, SHOULD also update the Sent Timestamp (if used) in the
   Command Header and the Message Authentication Digest in the
   Authentication CSLD.  The Message Authentication Digest is computed
   in the same way as the Control Request message.  The Random Number
   field can be reflected without modification.  The Session Identifier
   MAY be updated to reflect a locally significant unique value, MUST be
   0 if not specified.

2.2.  Measurement Phase

   Upon receiving the Control Response message with the Status set to
   Success, the second phase of the protocol, the Measurement Phase, is
   initiated.  In all other cases when the Status is not success no
   measurement traffic is initiated.  In the Measurement Phase the
   Sender sends a stream of measurement messages.  The measurement
   message stream consists of packets/frames that are spaced a
   configured number of milliseconds apart.







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       +-+-+-+-+-+-+-+      Measurement Request(n)    +-+-+-+-+-+-+-+
       |             |------------------------------->|             |
       |    Sender   |                                |  Responder  |
       |             |      Measurement Response(n)   |             |
       |             |<-------------------------------|             |
       +-+-+-+-+-+-+-+                                +-+-+-+-+-+-+-+

   The format of the Measurement messages as defined by this document
   for UDP Measurements is as shown below and is the same for the
   exchange in both directions, that is the format is the same when sent
   from the Sender to the Responder and when sent back from the
   Responder to the Sender with the only difference being the update of
   those fields that are designated with the Responder prefix, all other
   fields MUST remain unchanged.





































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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Measurement Type = 3        |         Reserved              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Sender SendTime                            |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Responder Receive Time                     |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Responder Send Time                        |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Sender Receive Time                        |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Sender Clock Offset                        |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Responder Clock Offset                     |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Sender Sequence No.                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Responder Sequence No.                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       .                                                               .
       .                          Data                                 .
       .                                                               .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields for the UDP Measurement Request have the following
   meaning:









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   +-------------+-----------+-----------------------------------------+
   | Field       | Size      | Description                             |
   |             | (bits)    |                                         |
   +-------------+-----------+-----------------------------------------+
   | Measurement | 16        | Carries the type of measurement being   |
   | Type        |           | performed; 1 - Reserved, 2 - Reserved,  |
   |             |           | 3 - UDP                                 |
   | ---------   | --------- | --------------------------              |
   | Reserved    | 16        | Reserved field and MUST be set to 0     |
   | ---------   | --------- | --------------------------              |
   | Sender Send | 64        | Carries the timestamp when the          |
   | Time        |           | measurement message was sent by Sender  |
   | ---------   | --------- | --------------------------              |
   | Responder   | 64        | Carries the timestamp when the          |
   | Receive     |           | measurement message was received by     |
   | Time        |           | Responder                               |
   | ---------   | --------- | --------------------------              |
   | Responder   | 64        | Carries the timestamp when the          |
   | Send Time   |           | measurement message was sent by the     |
   |             |           | Responder.  It MUST be 0 in the Sender  |
   |             |           | to Responder direction                  |
   | ---------   | --------- | --------------------------              |
   | Sender      | 64        | Carries the timestamp when the Sender   |
   | Receive     |           | received the measurement message.  It   |
   | Time        |           | MUST be 0 in both directions on the     |
   |             |           | wire and is filled on the Sender side   |
   |             |           | as soon as the measurement message is   |
   |             |           | received                                |
   | ---------   | --------- | --------------------------              |
   | Sender      | 64        | Gives an estimate of the Sender clock   |
   | Clock       |           | skew measured in second and fractional  |
   | Offset      |           | seconds                                 |
   | ---------   | --------- | --------------------------              |
   | Responder   | 64        | Gives an estimate of the Responder      |
   | Clock       |           | clock skew measured in seconds and      |
   | Offset      |           | fractional seconds                      |
   | ---------   | --------- | --------------------------              |
   | Sender      | 32        | The sequence number of the measurement  |
   | Sequence    |           | message on the Sender side.  This field |
   | Number      |           | is monotonically increasing and MAY     |
   |             |           | wraparound                              |
   | ---------   | --------- | --------------------------              |
   | Responder   | 32        | The sequence number of the measurement  |
   | Sequence    |           | message on the Responder side.  This    |
   | Number      |           | field is monotonically increasing and   |
   |             |           | MAY wraparound                          |
   | ---------   | --------- | --------------------------              |




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   | Data        | 32 bit    | This field is used to pad up to the     |
   |             | aligned   | configured request data size.  The      |
   |             |           | minimum requested data size SHOULD be   |
   |             |           | 512 bytes and this field will be of     |
   |             |           | length 512 minus the length of the      |
   |             |           | previous fields                         |
   +-------------+-----------+-----------------------------------------+

   Note: All timestamps have the format as described in RFC1305
   [RFC1305] and is as follows: the first 32 bits represent the unsigned
   integer number of seconds elapsed since 0h on 1 January 1900; the
   next 32 bits represent the fractional part of a second thereof.  The
   timestamp definition is also similar to RFC 4656 [RFC4656]


3.  Implementation notes

   Responder implementations SHOULD support simultaneous measurements
   destined to a single port either from the same or a different Sender.
   For different measurements that originate from the same sender, there
   MUST be a clear method for the Responder to distinguish the traffic,
   for example per a unique 5-tuple of protocol, source address, source
   port, destination address and destination port.

   A Control Request that is received for the same measurement request
   as identified by the 5-tuples, for instance, SHOULD result in the
   resetting of the duration timer as well as the Responder Sequence
   Number.

   A Control Phase followed by the Measurement Phase can be repeated to
   have continuous measurement over the entire time a device is alive.

   The Random Number field in the Measurement packets is to be set to a
   random value in environments where security is a concern.  It MUST
   always be included, when not used it MUST be set to all 0s.

   The Authentication CSLD MUST always be included.  When the mode field
   is set to 0, the Random Number field and the Message Authentication
   Digest MUST both be set to all 0s.  For the SHA256 authenticator mode
   the shared secret is prepended to the Control Message and the
   authentication algorithm is then run over the complete data including
   the shared secret.

   If the UDP port indicated in the UDP Measurement CSLD is busy, the
   Responder MAY suggest an alternative port, the Status of the UDP
   Measurement CSLD MUST be set to Success in that case.  The Sender MAY
   set a value of 0 in the field, in which case the Responder MAY choose
   to open a port and send that back along with the Status of Success.



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   It should be noted that this behavior has security ramifications and
   the port needs to be chosen very carefully by the Responder.

   All messages and all fields within a message are assumed to be in
   network order.  In addition, all data fields are unsigned unless
   mentioned otherwise.


4.  Extensions

   This section describes how the protocol can be extended to allow for
   additional functionality, such as new types of measurements.

   In order to allow for new types of measurements, additional
   Measurement Type CSLDs can be defined, to be carried in place of the
   UDP Measurement CSLD defined in this document within the Control
   Request and Control Response messages.  The meaning and precise
   format of such CSLD needs to be defined in a separate specification.
   Such a specification will also need to describe the appropriate
   formats for the messages in the Measurement Phase.

   In addition, the protocol can be extended by adding support for new
   registry values for registries defined in this document.


5.  IANA Considerations

   The following registries are needed to maintain the extensibility of
   the protocol.

   Cisco Service Level Assurance Protocol - Version Number Registry

           +-----------+---------------------------------------+
           | Version   | Description                           |
           +-----------+---------------------------------------+
           | 1         | Reserved                              |
           | 2         | Version for protocol in this document |
           | 3 - 200   | Available or future extensions        |
           | 201 - 255 | Experimental values for private use   |
           +-----------+---------------------------------------+

   The version number should only be changed when the structure of the
   Command Messages is different from the basic Command Header and CSLD
   structure described in this document.

   Cisco Service Level Assurance Protocol - CSLD Command Registry





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            +-----------+-------------------------------------+
            | CSLD Type | Description                         |
            +-----------+-------------------------------------+
            | 1         | Authentication CSLD                 |
            | 2         | UDP Measurements                    |
            | 3 - 255   | Available for future extensions     |
            | 256+      | Experimental values for private use |
            +-----------+-------------------------------------+

   It is envisioned that future documents will provide their own
   measurement type number along with the format of the Data portion.

   Cisco Service Level Assurance Protocol - Status Types Registry

   +-----------+-------------------------------------------------------+
   | Status    | Description                                           |
   +-----------+-------------------------------------------------------+
   | 0         | Success                                               |
   | --------- | --------------------------                            |
   | 1         | Fail - catch all                                      |
   | --------- | --------------------------                            |
   | 2         | Authentication failure                                |
   | --------- | --------------------------                            |
   | 3         | Format error - sent when any CSLD type is not         |
   |           | recognized or any part of a CSLD has a value that is  |
   |           | not recognized                                        |
   | --------- | --------------------------                            |
   | 4         | Port in use - the UDP/TCP port is already being used  |
   |           | by some other application and cannot be reserved      |
   | --------- | --------------------------                            |
   | 5 - 200   | Available for future extensions                       |
   | --------- | --------------------------                            |
   | 201 - 255 | Experimental values for private use                   |
   +-----------+-------------------------------------------------------+

   Cisco Service Level Assurance Protocol - Authenticator Modes Registry

            +-----------+-------------------------------------+
            | Mode      | Description                         |
            +-----------+-------------------------------------+
            | 0         | No Authentication                   |
            | 1         | SHA256                              |
            | 2         | HMAC-SHA-256                        |
            | 3 - 200   | Available for future extensions     |
            | 201 - 255 | Experimental values for private use |
            +-----------+-------------------------------------+

   Cisco Service Level Assurance Protocol - Address Registry



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          +--------------+-------------------------------------+
          | Address Type | Description                         |
          +--------------+-------------------------------------+
          | 1            | IPv4                                |
          | 2            | IPv6                                |
          | 3 - 200      | Available for future extensions     |
          | 201 - 255    | Experimental values for private use |
          +--------------+-------------------------------------+

   Cisco Service Level Assurance Protocol - Roles Registry

            +-----------+-------------------------------------+
            | Role      | Description                         |
            +-----------+-------------------------------------+
            | 1         | Sender                              |
            | 2         | Responder                           |
            | 3 - 200   | Available for future extensions     |
            | 201 - 255 | Experimental values for private use |
            +-----------+-------------------------------------+

   Cisco Service Level Assurance Protocol - Measurement Type Registry

        +------------------+-------------------------------------+
        | Measurement Type | Description                         |
        +------------------+-------------------------------------+
        | 1                | Reserved                            |
        | 2                | Reserved                            |
        | 3                | UDP                                 |
        | 4 - 255          | Available for future extensions     |
        | 256+             | Experimental values for private use |
        +------------------+-------------------------------------+


6.  Security Considerations

6.1.  Message Authentication

   When the mode for the Authentication CSLD is set to 1, the Message
   Authentication Digest is generated using the SHA 256 algorithm and is
   to be calculated over the entire packet including the Message
   Authentication Digest field which MUST be set to all 0s.

   When the mode for the Authentication CSLD is set to 2, the Message
   Authentication Digest is generated using the HMAC-SHA-256 as
   described in RFC 4868 [RFC4868]algorithm and is to be calculated over
   the entire packet including the Message Authentication Digest field
   which MUST be set to all 0s




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   When the mode field is set to 0, the Random Number field and the
   Message Authentication Digest MUST both be set to all 0s.

6.2.  IPSec Considerations

   It is RECOMMENDED that IPSec be employed to afford better security.
   IPSec provides enhanced privacy as well as an automated key
   distribution mechanism.  The following recommendations are similar to
   RFC3579, Section 2 [RFC3579]

6.2.1.  Control Traffic

   For Senders implementing this specification, the IPSec policy would
   be "Initiate IPSec, from me to any, destination port UDP 1167".  This
   causes the Sender to initiate IPSec when sending Control traffic to
   any Responder.  If some Responders contacted by the Sender do not
   support IPSec, then a more granular policy will be required, such as
   "Initiate IPSec, from me to IPSec-Capable-Responder, destination port
   UDP 1167".

   For Responders implementing this specification, the IPSec policy
   would be "Require IPSec, from any to me, destination port UDP 1167".
   This causes the Responder to require use of IPSec.  If some Sender
   does not support IPSec, then a more granular policy will be required:
   "Require IPSec, from IPSec-Capable-Sender to me".

6.2.2.  Measurement Traffic

   As the Control Phase occurs before the Measurement Phase, it should
   be possible to build an IPSec Security Association once a successful
   Control Response is received.

   For Senders implementing this specification, the IPSec policy would
   be "Initiate IPSec, from me to negotiated address, destination is
   negotiated port".  This causes the Sender to initiate IPSec when
   sending Measurement traffic to the Responder.  If some Responders
   contacted by the Sender do not support IPSec, then a more granular
   policy will be required, such as "Initiate IPSec, from me to IPSec-
   Capable-Responder, destination is negotiated port".

   For Responders implementing this specification, the IPSec policy
   would be "Require IPSec, from negotiated address to me, destination
   is negotiated port".  This causes the Responder to require use of
   IPSec.  If some Sender does not support IPSec, then a more granular
   policy will be required: "Require IPSec, from IPSec-Capable-Sender to
   me, destination is negotiated port".





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6.3.  Replay Protection

   For the Control Messages the originator of the message MAY choose to
   include a current value in the Sent Timestamp field indicating the
   time the message was sent, it MUST be set to 0 otherwise.  The
   receiver of the message MAY choose to validate if the timestamp is
   within an acceptable range.  The Measurement Traffic described in
   this document contains a timestamp to indicate the sent time and
   hence no new field is required.


7.  Terminology

   +-------------+-----------------------------------------------------+
   | Term        | Description                                         |
   +-------------+-----------------------------------------------------+
   | Control     | A phase during which Control Request and Control    |
   | Phase       | Response is exchanged.                              |
   | ---------   | --------------------------                          |
   | L2          | OSI Data Link Layer                                 |
   | ---------   | --------------------------                          |
   | L3          | OSI Network Layer                                   |
   | ---------   | --------------------------                          |
   | Measurement | Active measurement phase that is marked by a        |
   | Phase       | sequence of Measurement Request and Measurement     |
   |             | Response exchanges.                                 |
   | ---------   | --------------------------                          |
   | Metric      | A particular characteristic of the network data     |
   |             | traffic, for example latency, jitter, packet/frame  |
   |             | loss                                                |
   | ---------   | --------------------------                          |
   | Responder   | A network element that responds to a message        |
   | ---------   | --------------------------                          |
   | RTP         | Real-time Transport Protocol                        |
   | ---------   | --------------------------                          |
   | Sender      | A network element that is the initiator of a        |
   |             | message exchange                                    |
   | ---------   | --------------------------                          |
   | Service     | This is the level of service that is agreed upon    |
   | Level       | between the Provider and the Customer               |
   | ---------   | --------------------------                          |
   | UDP         | User Datagram Protocol                              |
   +-------------+-----------------------------------------------------+








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8.  Acknowledgements

   The authors wish to acknowledge the contributions of several key
   people who contributed to the current form of the document.  Hanlin
   Fang, David Wang, Anantha Ramaiah, Max Pritikin, and Malini
   Vijayamohan.


9.  References

9.1.  Normative References

   [RFC1305]  Mills, D., "Network Time Protocol (Version 3)
              Specification, Implementation", RFC 1305, March 1992.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
              384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007.

9.2.  Informative References

   [RFC3579]  Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication
              Dial In User Service) Support For Extensible
              Authentication Protocol (EAP)", RFC 3579, September 2003.

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol
              (OWAMP)", RFC 4656, September 2006.


Authors' Addresses

   Murtaza S. Chiba
   Cisco Systems
   170 West Tasman Drive
   San Jose,   95134
   USA

   Phone: 1-408-526-4000
   Fax:
   Email: mchiba@cisco.com
   URI:







Murtaza S. Chiba, et al.  Expires May 18, 2012                 [Page 24]

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   Alexander Clemm
   Cisco Systems
   170 West Tasman Drive
   San Jose,   95134
   USA

   Phone: 1-408-526-4000
   Fax:
   Email: alex@cisco.com
   URI:


   Steven Medley
   Cisco Systems
   170 West Tasman Drive
   San Jose,   95134
   USA

   Phone: 1-408-526-4000
   Fax:
   Email: stmedley@cisco.com
   URI:


   Joseph Salowey
   Cisco Systems
   170 West Tasman Drive
   San Jose,   95134
   USA

   Phone: 1-408-526-4000
   Fax:
   Email: jsalowey@cisco.com
   URI:


   Sudhir Thombare
   Cisco Systems
   170 West Tasman Drive
   San Jose,   95134
   USA

   Phone: 1-408-526-4000
   Fax:
   Email: thombare@cisco.com
   URI:





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   Eshwar Yedavalli
   Cisco Systems
   170 West Tasman Drive
   San Jose,   95134
   USA

   Phone: 1-408-526-4000
   Fax:
   Email: eshwar@cisco.com
   URI:









































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