Internet DRAFT - draft-cisco-sla-protocol
draft-cisco-sla-protocol
Network Working Group Murtaza S. Chiba
Internet-Draft Alexander Clemm
Intended status: Informational Steven Medley
Expires: April 22, 2013 Joseph Salowey
Sudhir Thombare
Eshwar Yedavalli
Cisco Systems
October 19, 2012
Cisco Service Level Assurance Protocol
draft-cisco-sla-protocol-04
Abstract
Cisco's Service Level Assurance Protocol (Cisco's SLA Protocol) is a
Performance Measurement 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 Cisco SLA Protocol UDP measurement type to enable
vendor interoperability.
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 April 22, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Control Phase . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1. Control Request . . . . . . . . . . . . . . . . . . . 6
2.1.1.1. Command Header . . . . . . . . . . . . . . . . . . 7
2.1.1.2. CSLDs . . . . . . . . . . . . . . . . . . . . . . 9
2.1.2. Control Response Message . . . . . . . . . . . . . . . 15
2.2. Measurement Phase . . . . . . . . . . . . . . . . . . . . 16
3. Implementation notes . . . . . . . . . . . . . . . . . . . . . 19
4. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 23
6.1. Message Authentication . . . . . . . . . . . . . . . . . . 23
6.2. IPSec Considerations . . . . . . . . . . . . . . . . . . . 24
6.2.1. Control Traffic . . . . . . . . . . . . . . . . . . . 24
6.2.2. Measurement Traffic . . . . . . . . . . . . . . . . . 24
6.3. Replay Protection . . . . . . . . . . . . . . . . . . . . 25
7. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 25
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.1. Normative References . . . . . . . . . . . . . . . . . . . 26
9.2. Informative References . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27
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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 increasingly becoming an important tool to monitor
Service Level guarantees and, in general, to monitor the health of a
network.
Performance metrics, both one-way and two-way, can be used for pre-
deployment validation as well as for measuring in-band live network
performance characteristics. It can be used to measure service
levels in L2 and L3 networks as well as for applications running on
top of L3. Performance measurements are gathered by analyzing
actively generated synthetic request and response packets/frames.
This is in contrast to passive measurements that analyze production
traffic flowing through a particular network element.
There is a growing body of work on Performance Measurement standards
that enable interoperability between different vendors network
elements by describing common measurement protocols as well as
metrics. IETF has actively developed standards on the subject and
two such standards are One-Way Active Measurement Protocol(OWAMP)
[RFC4656] and Two-Way Active Measurement Protocol (TWAMP) [RFC5357].
Cisco's SLA Protocol is another example of a performance measurement
protocol that offers a rich set of measurement message types. The
measurement types can be classified as those that test connectivity
(ping like) by providing round trip or, one-way latency measures and
those that provide a richer set of statistics including network
jitter and packet/frame loss. Each type of active measurement
exchanges mimic an actual protocol exchange.
Cisco's SLA Protocol UDP measurement message exchanges, as covered in
this document to enable interoperability, simulates a UDP application
and can be used to simulate either Voice or Video traffic that is
encoded 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.
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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:
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+-+-+-+-+-+-+-+ 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, in addition, 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 the requested 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.
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+-+-+-+-+-+-+-+ 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 submitted for transmission and is |
| | | updated for a response. This field MAY |
| | | be used when security is of concern in |
| | | order to prevent replay attacks. SHOULD |
| | | be updated for a response. When not |
| | | being used it MUST be set to all 0's. |
| | | The format is as given in RFC5905 |
+-----------+-----------+-------------------------------------------+
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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 in |
| | | octets. |
| --------- | --------- | -------------------------- |
| 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 when security is of concern |
| | | and is useful to prevent dictionary |
| | | attacks. 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
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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 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: Duration is specified in seconds.
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 in |
| Length | | octets. |
| --------- | --------- | -------------------------- |
| Address | 8 | Indicates the address type and is set |
| Type | | to one of the values in the Cisco |
| | | Service Level Performance Measurement |
| | | Protocol - Address Family 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 |
| --------- | --------- | -------------------------- |
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| 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 |
| --------- | --------- | -------------------------- |
| 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 |
+-------------+-----------+-----------------------------------------+
Note: The source addresses are only indicative of identity of the
originator and cannot be used as destination address for responses in
a NAT environment.
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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:
+-----------+-------------------------------------------------------+
| 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 MUST be reflected without modification. The Session Identifier
MAY be updated to reflect a locally significant unique value, MUST be
0 if not specified.
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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.
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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 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:
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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 submitted for |
| | | transmission 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 submitted for |
| | | transmission 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 size for this field SHOULD be |
| | | 64 octets. |
+-------------+-----------+-----------------------------------------+
Note: All timestamps have the default 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 or defaults to
the format as defined in RFC 5905. [RFC5905]
3. Implementation notes
Responder implementations SHOULD support simultaneous measurements
destined to a single port either from the same or a different Sender.
For different measurement instances 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 in
order to have a 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 and is used
to prevent dictionary attacks. It MUST always be included, when not
used it MUST be set to all 0s.
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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. The SHA256 mode is included for ease of
implementation and it is recommended to use the HMAC variant to
afford better security.
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.
The default format for all timestamps is as specified in RFC 5905.
[RFC5905]
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 within the
Control Request and Control Response messages in place of the UDP
Measurement CSLD defined in this document . 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
values to registries defined in this document.
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5. IANA Considerations
The following registries are needed for the extensibility of the
protocol and the terms 'Private Use' and 'Experimental Use' found in
the registries in this section have the same meaning as described in
RFC 5226 [RFC5226].
Furthermore, for the following registries, the ranges designated
"Available for future extensions" will be governed by the policy 'RFC
Required' as described in RFC 5226 [RFC5226].
Cisco Service Level Assurance Protocol - Version Number Registry
+-----------+---------------------------------+
| Version | Description |
+-----------+---------------------------------+
| 0 | Reserved |
| 1 | Reserved |
| 2 | Version 2 |
| 3 - 200 | Available for future extensions |
| 201 - 225 | Private Use |
| 226 - 255 | Experimental Use |
+-----------+---------------------------------+
The version number should be changed only 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
+---------------+---------------------------------+
| CSLD Type | Description |
+---------------+---------------------------------+
| 0 | Reserved |
| 1 | Authentication CSLD |
| 2 | UDP Measurements |
| 3 - 52 | Reserved |
| 53 - 10239 | Available for future extensions |
| 10240 - 20479 | Private Use |
| 20480 - 65535 | Experimental 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 - Authenticator Modes Registry
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+-----------+---------------------------------+
| Mode | Description |
+-----------+---------------------------------+
| 0 | No Authentication |
| 1 | SHA256 |
| 2 | HMAC-SHA-256 |
| 3 - 200 | Available for future extensions |
| 201 - 225 | Private Use |
| 226 - 255 | Experimental Use |
+-----------+---------------------------------+
Cisco Service Level Assurance Protocol - Roles Registry
+-----------+---------------------------------+
| Role | Description |
+-----------+---------------------------------+
| 0 | Reserved |
| 1 | Sender |
| 2 | Responder |
| 3 - 200 | Available for future extensions |
| 201 - 225 | Private Use |
| 226 - 255 | Experimental Use |
+-----------+---------------------------------+
Cisco Service Level Assurance Protocol - Measurement Type Registry
+------------------+---------------------------------+
| Measurement Type | Description |
+------------------+---------------------------------+
| 0 | Reserved |
| 1 | Reserved |
| 2 | Reserved |
| 3 | UDP |
| 4 - 52 | Reserved |
| 53-10239 | Available for future extensions |
| 10240 - 20479 | Private Use |
| 20480 - 65535 | Experimental Use |
+------------------+---------------------------------+
The following registry is also needed for the extensibility of the
protocol, however, the range designated "Available for future
extensions" will be governed by the policy 'First Come First Served'
as described in RFC 5226 [RFC5226]
Cisco Service Level Assurance Protocol - Status Types Registry
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+-----------+-------------------------------------------------------+
| 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 - 40959 | Available for future extensions |
| --------- | -------------------------- |
| 40960 - | Experimental Use |
| 65535 | |
+-----------+-------------------------------------------------------+
Finally, the following registry is also needed for the extensibility
of the protocol, however, the range designated "Available for future
extensions" will be governed by the policy 'Specification Required'
as described in RFC 5226 [RFC5226]
Cisco Service Level Assurance Protocol - Address Family Registry
+--------------+---------------------------------+
| Address Type | Description |
+--------------+---------------------------------+
| 0 | Reserved |
| 1 | IPv4 |
| 2 | IPv6 |
| 3 - 200 | Available for future extensions |
| 201 - 225 | Private Use |
| 226 - 255 | Experimental 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
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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".
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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
+-------------+-----------------------------------------------------+
| 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 |
| --------- | -------------------------- |
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| UDP | User Datagram Protocol |
+-------------+-----------------------------------------------------+
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
[IEEE1588]
IEEE, "1588-2008 Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", March 2008.
[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.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
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.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008.
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[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374, September 2011.
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:
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:
Murtaza S. Chiba, et al. Expires April 22, 2013 [Page 27]
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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:
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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