Cisco Service Level Assurance Protocol
draft-cisco-sla-protocol-02

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 February 11, 2013.

Copyright Notice

Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.

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
• 2. Protocol
• 2.1. Control Phase
• 2.1.1. Control Request
• 2.1.1.1. Command Header
• 2.1.1.2. CSLDs
• 2.1.1.2.1. Authentication CSLD
• 2.1.1.2.2. UDP Measurement CSLD
• 2.1.2. Control Response Message
• 2.2. Measurement Phase
• 3. Implementation notes
• 4. Extensions
• 5. IANA Considerations
• 6. Security Considerations
• 6.1. Message Authentication
• 6.2. IPSec Considerations
• 6.2.1. Control Traffic
• 6.2.2. Measurement Traffic
• 6.3. Replay Protection
• 7. Terminology
• 8. Acknowledgements
• 9. References
• 9.1. Normative References
• 9.2. Informative References
• Authors' Addresses

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 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. Each Measurement Request message is acknowledged by the Responder with a Measurement Response Message.

The number and frequency with which messages are sent SHOULD be controlled by configuration on the Sender element, along with the waiting time for a Control Response.

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)          |
           |<---------------------------------------------|
           |                                              | 

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.

     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:

     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:

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:

• The Authentication CSLD
• 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

     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

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:

     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                              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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

Note: The source addresses are only indicative of identity of the originator and cannot be used as destination for responses in a NAT environment.

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:

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.

                

    +-+-+-+-+-+-+-+      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.

     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 Send Time                           |
    +                                                               +
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    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:

Note: All timestamps have the format as described in RFC 5905 [RFC5905] 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]

In addition, the timestamp format used can be as described for the low-order 64 bits of the IEEE 1588-2008 (1588v2) Precision Time Protocol timestamp format [IEEE1588]. This truncated format consists of a 32-bit seconds field followed by a 32-bit nanoseconds field, and is the same as the IEEE 1588v1 timestamp format. This timestamp definition is similar to the default timestamp as specified in RFC 6374 [RFC6374]

Implementations MUST use only one of the two formats. The chosen format is negotiated out-of-band between the endpoints.

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

The measurement stream typically consists of packets/frames with a periodic inter-packet distribution. The Sender need not wait for a Measurement Response packet to arrive before sending another Measurement Request packet, and in many cases it will not be possible in order to maintain the desired inter-packet distribution.

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

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

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

Cisco Service Level Assurance Protocol - Authenticator Modes Registry

Cisco Service Level Assurance Protocol - Address Registry

Cisco Service Level Assurance Protocol - Roles Registry

Cisco Service Level Assurance Protocol - Measurement Type Registry

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

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".

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 submitted for transmission, 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

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

9.2. Informative References

Authors' Addresses