IPPM WG R. Civil
Internet-Draft Ciena Corporation
Intended status: Standards Track A. Morton
Expires: September 10, 2015 AT&T Labs
L. Zheng
Huawei Technologies
R. Rahman
Cisco Systems
M. Jethanandani
Ciena Corporation
K. Pentikousis, Ed.
EICT
March 9, 2015
Two-Way Active Measurement Protocol (TWAMP) Data Model
draft-cmzrjp-ippm-twamp-yang-00
Abstract
This document specifies a data model for client and server
implementations of the Two-Way Active Measurement Protocol (TWAMP).
We define the TWAMP data model through Unified Modeling Language
(UML) class diagrams and formally specify it using YANG.
Status of This Memo
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This Internet-Draft will expire on September 10, 2015.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Document Organization . . . . . . . . . . . . . . . . . . 3
2. Scope, Model, and Applicability . . . . . . . . . . . . . . . 4
3. Data Model Overview . . . . . . . . . . . . . . . . . . . . . 5
3.1. Control-Client . . . . . . . . . . . . . . . . . . . . . 5
3.2. Server . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 7
3.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 7
4. Data Model Parameters . . . . . . . . . . . . . . . . . . . . 7
4.1. Control-Client . . . . . . . . . . . . . . . . . . . . . 7
4.2. Server . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 17
4.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 20
5. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 23
5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 26
6. Data Model Examples . . . . . . . . . . . . . . . . . . . . . 39
6.1. Control-Client . . . . . . . . . . . . . . . . . . . . . 40
6.2. Server . . . . . . . . . . . . . . . . . . . . . . . . . 41
6.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 42
6.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 43
7. Security Considerations . . . . . . . . . . . . . . . . . . . 44
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 45
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 45
10.1. Normative References . . . . . . . . . . . . . . . . . . 45
10.2. Informative References . . . . . . . . . . . . . . . . . 46
Appendix A. Detailed Data Model Examples . . . . . . . . . . . . 47
A.1. Control-Client . . . . . . . . . . . . . . . . . . . . . 47
A.2. Server . . . . . . . . . . . . . . . . . . . . . . . . . 48
A.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 49
A.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 50
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52
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1. Introduction
The Two-Way Active Measurement Protocol (TWAMP) [RFC5357] can be used
to measure network performance parameters such as latency, bandwidth,
and packet loss by sending probe packets and monitoring their
experience in the network. To date, TWAMP implementations do not
come with a standard management framework and, as such, configuration
depends on the various proprietary mechanisms developed by the
corresponding TWAMP vendor.
1.1. Motivation
For large, virtualized, and dynamically instantiated infrastructures
where network functions are placed according to orchestration
algorithms as discussed in [I-D.unify-nfvrg-challenges], proprietary
mechanisms for managing TWAMP measurements have severe limitations.
For current deployments, the lack of standardized programmable data
model limits the flexibility to dynamically instantiate TWAMP-based
measurement across equipment from different vendors.
We note that earlier efforts to define, for example, a TWAMP
Management Information Base (MIB) [I-D.elteto-ippm-twamp-mib] did not
advance. As we move forward, two major trends call for revisiting
the standardization on TWAMP management aspects. First, we expect
that in the coming years large-scale and multi-vendor TWAMP
deployments will become the norm. From an operations perspective,
dealing with several vendor-specific TWAMP configuration mechanisms
is simply unsustainable in this context. Second, the increasingly
software-defined and virtualized nature of network infrastructures,
based on dynamic service chains [NSC] and programmable control and
management planes [RFC7426] requires a well-defined data model for
TWAMP implementations. This document defines such a TWAMP data model
and specifies it formally using the YANG data modeling language
[RFC6020].
1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.3. Document Organization
The rest of this document is organized as follows. Section 2
presents the scope and applicability of this document. Section 3
provides a high-level overview of the TWAMP data model. Section 4
details the configuration parameters of the data model and Section 5
specifies the YANG module. Section 6 lists illustrative examples
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which conform to the YANG module specified in this document.
Appendix A elaborates these examples further.
2. Scope, Model, and Applicability
The purpose of this document is the specification of vendor-
independent data model for TWAMP implementations.
Figure 1 illustrates a redrawn version of the TWAMP logical model
found in [RFC5357], Section 1.2. The figure is annotated with
pointers to the UML diagrams provided in this document and associated
with the data model of the four logical entities in a TWAMP
deployment, namely the TWAMP Control-Client, Server, Session-Sender
and Session-Reflector. As per [RFC5357], unlabeled links in the
figure are unspecified and may be proprietary protocols.
[Fig. 3] [Fig. 4]
+----------------+ +--------+
| Control-Client | <-- TWAMP-Control --> | Server |
+----------------+ +--------+
^ ^
| |
V V
+----------------+ +-------------------+
| Session-Sender | <-- TWAMP-Test --> | Session-Reflector |
+----------------+ +-------------------+
[Fig. 5] [Fig. 6]
Figure 1: Annotated TWAMP logical model
As discussed in [RFC5357], a TWAMP implementation may follow a
simplified logical model, in which the same node acts both as the
Control-Client and Session-Sender, while another node acts at the
same time as the TWAMP Server and Session-Reflector. Figure 2
illustrates this simplified logical model and indicates the
interaction between the TWAMP configuration client and server using,
for instance, NETCONF [RFC6241] or RESTCONF
[I-D.ietf-netconf-restconf]. Note, however, that the specific
protocol used to communicate the TWAMP configuration parameters
specified herein is outside the scope of this document.
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o-------------------o o-------------------o
| Config client | | Config client |
o-------------------o o-------------------o
|| ||
NETCONF || RESTCONF NETCONF || RESTCONF
|| ||
o-------------------o o-------------------o
| Config server | | Config server |
| [Fig. 3, 5] | | [Fig. 4, 6] |
+-------------------+ +-------------------+
| Control-Client | <-- TWAMP-Control --> | Server |
| | | |
| Session-Sender | <-- TWAMP-Test --> | Session-Reflector |
+-------------------+ +-------------------+
Figure 2: Simplified TWAMP model and protocols
3. Data Model Overview
A TWAMP data model includes four categories of configuration items.
Global configuration items relate to parameters that are set on a per
device level. For example, the administrative status of the device
with respect to whether it allows TWAMP sessions and if so in what
capacity (e.g. Control-Client, Server or both) are typical instances
of global configuration items. A second category includes attributes
that can be configured on a per control connection basis, such as the
Server IP address. A third category includes attributes related to
per-test session attributes, for instance setting different values in
the Differentiated Services Code Point (DSCP) field. Finally, the
data model could include attributes that relate to the operational
state of the TWAMP implementation.
As we describe the TWAMP data model in the remaining sections of this
document, readers should keep in mind the functional entity grouping
illustrated in Figure 1.
3.1. Control-Client
A TWAMP Control-Client has an administrative status field set at the
device level that indicates whether the node is enabled to function
as such.
Each TWAMP Control-Client is associated with zero or more TWAMP
control connections. The main configuration parameters of each
control connection are:
o A name which can be used to uniquely identify, at the Control-
Client, a particular control connection. This name is necessary
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for programmability reasons because at the time of creation of a
TWAMP control connection not all IP and TCP port information
needed to uniquely identify the connection is available.
o The IP address of the interface the Control-Client will use for
connections
o The IP address of the remote Server
o Authentication and Encryption attributes such as KeyID, Token and
the Client Initialization Vector (Client-IV) [RFC4656].
Each TWAMP control connection, in turn, is associated with zero or
more test sessions. For each test session we note the following
configuration items:
o The test session name that uniquely identifies a particular test
session at the Control-Client and Session-Sender. Similarly to
the control connections above, this unique test session name is
needed because at the time of creation of a test session the
source UDP port is not known to uniquely identify the test
session.
o The IP address and UDP port number of the Session-Sender of the
path under test by TWAMP
o The IP address and UDP port number of the Session-Reflector of
said path
o Information pertaining to the test packet stream, such as the test
starting time or whether the test should be repeated.
3.2. Server
Each TWAMP Server has an administrative status field set at the
device level to indicate whether the node is enabled to function as a
TWAMP Server.
Each TWAMP Server is associated with zero or more control
connections. Each control connection is uniquely identified by the
4-tuple {Control-Client IP address, Control-Client TCP port number,
Server IP address, Server TCP port}. Control connection configuration
items on a TWAMP Server are read-only.
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3.3. Session-Sender
There is one TWAMP Session-Sender instance for each test session that
is initiated from the sending device. Primary configuration fields
include:
o The test session name that MUST be identical with the
corresponding test session name on the TWAMP Control-Client
(Section 3.1)
o The control connection name, which along with the test session
name uniquely identify the TWAMP Session-Sender instance
o Information pertaining to the test packet stream, such as, for
example, the value used in the DSCP packet header field and the
number of test packets.
3.4. Session-Reflector
Each TWAMP Session-Reflector is associated with zero or more test
sessions. For each test session, the REFWAIT parameter can be
configured. Read-only access to other data model parameters, such as
the Sender IP address is foreseen. Each test session can be uniquely
identified by the 4-tuple mentioned in Section 3.2.
4. Data Model Parameters
This section defines the TWAMP data model using UML and describes all
associated parameters.
4.1. Control-Client
The twampClient container (see Figure 3) holds items that are related
to the configuration of the TWAMP Control-Client logical entity.
These are divided up into items that are associated with the
configuration of the Control-Client as a whole (e.g.
clientAdminState) and items that are associated with individual
control connections initiated by that Control-Client entity
(twampClientCtrlConnection).
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+------------------+
| twampClient |
+------------------+ 1..* +---------------------+
| clientAdminState |<>-------------------------| modePreferenceChain |
| | +---------------------+
| | 1..* +-----------+ | priority |
| |<>------| keyChain | | mode |
+------------------+ +-----------+ +---------------------+
^ | keyID |
V | secretKey |
| +-----------+
| 0..*
+---------------------------+
| twampClientCtrlConnection |
+---------------------------+
| ctrlConnectionName | 0..* +-----------------------+
| clientIp |<>-------| twampSessionRequest |
| serverIp | +-----------------------+
| serverTcpPort | | testSessionName |
| dscp | | senderIp |
| keyId | | senderUdpPort |
| dkLen | | reflectorIp |
| clientTcpPort {ro} | | reflectorUdpPort |
| serverStartTime {ro} | | timeout |
| ctrlConnectionState {ro} | | paddingLength |
| selectedMode {ro} | | startTime |
| token {ro} | | repeat |
| clientIv {ro} | | repeatInterval |
+---------------------------+ | pmIndex |
| testSessionState {ro} |
| sid {ro} |
+-----------------------+
Figure 3: TWAMP Control-Client UML class diagram
The twampClient container includes an administrative parameter
(clientAdminState) that controls whether the device is allowed to
initiate TWAMP control and test sessions.
The twampClient container holds a list which specifies the preferred
Mode values according to their preferred order of use, including the
authentication and encryption Modes. Specifically,
modePreferenceChain lists each priority (expressed as a 16-bit
unsigned integer, where zero is the highest priority and subsequent
values monotonically increasing) with their corresponding mode
(expressed as a 32-bit Hexadecimal value). Depending on the Modes
available in the Server Greeting, the Control-Client MUST choose the
highest priority Mode from the configured modePreferenceChain list.
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Note that the list of preferred Modes may set bit position
combinations when necessary, such as when referring to the extended
TWAMP features in [RFC5618], [RFC5938], and [RFC6038]. If the
Control-Client cannot determine an acceptable Mode, it MUST respond
with zero Mode bits set in the Set-up Response message, indicating it
will not continue with the control connection.
In addition, the twampClient container holds a list named keyChain
which relates KeyIDs with the respective secret keys. Both the
Server and the Control-Client use the same mappings from KeyIDs to
shared secrets. The Server, being prepared to conduct sessions with
more than one Control-Client, uses KeyIDs to choose the appropriate
secret key; a Control-Client would typically have different secret
keys for different Servers. keyId is a UTF-8 string, up to 80 octets
in length (if the string is shorter, it is padded with zero octets),
that tells the Server which shared secret the Control-Client wishes
to use to authenticate or encrypt. The secretKey is the shared
secret, an octet string of arbitrary length whose interpretation as a
text string is unspecified. In the interest of interoperability,
however, the UTF-8 text encoding MUST be used for secretKey.
Each twampClient container also holds a list of
twampClientCtrlConnection, where each item in the list describes a
TWAMP control connection that will be initiated by this Control-
Client. There SHALL be one instance of twampClientCtrlConnection per
TWAMP Control (TCP) connection that is to be initiated from this
device.
The configuration items for twampClientCtrlConnection are:
ctrlConnectionName
A unique name used as a key to identify this individual TWAMP
control connection on the Control-Client device.
clientIp
The IP address of the local Control-Client device, to be
placed in the source IP address field of the IP header in
TWAMP TCP control packets belonging to this control
connection. If not configured, the device SHALL choose its
own source IP address.
serverIp
The IP address belonging to the remote Server device to which
the control connection will be initiated to.
serverTcpPort
This parameter defines the TCP port number that is to be used
by this outgoing TWAMP control connection. Typically, this
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is the well-known TWAMP port number (862) [RFC5357].
However, there are known realizations of TWAMP in the field
that were implemented before this well-known port number was
allocated. These early implementations allowed the port
number to be configured. This parameter is therefore
provided for backward compatibility reasons.
dscp The DSCP value to be placed in the TCP header of TWAMP-
Control packets generated by this Control-Client.
keyId
The keyId value that is selected for this control connection.
KeyID a UTF-8 string, up to 80 octets in length (if the
string is shorter, it is padded with zero octets).
dkLen Intended length in octets of the derived key, a positive
integer, at most (2^32 - 1) * hLen.
The following twampClientCtrlConnection parameters are read-only:
clientTcpPort
The source TCP port used in the TWAMP control packets
belonging to this control connection.
serverStartTime
The Start-Time advertized by the Server in the Server-Start
message ([RFC4656], Section 3.1). This is a timestamp
representing the time when the current instantiation of the
Server started operating.
ctrlConnectionState
The control connection state can be either active or idle.
selectedMode
The mode that the Control-Client has chosen for this control
connection as set in the Mode field of the Set-Up-Response
message ([RFC4656], Section 3.1).
token This parameter holds the 64 octets containing the
concatenation of a 16-octet challenge, a 16-octet AES
Session-key used for encryption, and a 32-octet HMAC-SHA1
Session-key used for authentication. AES Session-key and
HMAC Session-key are generated randomly by the Control-
Client. AES Session-key and HMAC Session-key MUST be
generated with sufficient entropy not to reduce the security
of the underlying cipher [RFC4086]. The token itself is
encrypted using the AES (Advanced Encryption Standard) in
Cipher Block Chaining (CBC). Encryption MUST be performed
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using an Initialization Vector (IV) of zero and a key derived
from the shared secret associated with KeyID. Challenge is
the same as transmitted by the Server (Section 4.2) in the
clear; see also the last paragraph of Section 6 in [RFC4656].
clientIv
The Control-Client Initialization Vector (Client-IV) is
generated randomly by the Control-Client. Client-IV merely
needs to be unique (i.e., it MUST never be repeated for
different sessions using the same secret key; a simple way to
achieve that without the use of cumbersome state is to
generate the Client-IV values using a cryptographically
secure pseudo-random number source.
Each twampClientCtrlConnection holds a list of twampSessionRequest.
twampSessionRequest holds information associated with the Control-
Client for this test session. This includes information that is
associated with the Request-TW-Session/Accept-Session message
exchange ([RFC5357], Section 3.5). The Control-Client is also
responsible for scheduling and results collection for test sessions,
so twampSessionRequest will also hold information related these
actions (e.g. pmIndex, repeatInterval). There SHALL be one instance
of twampSessionRequest for each test session that is to be negotiated
by this control connection via a Request-TW-Session/Accept-Session
exchange.
The configuration items for twampSessionRequest are:
testSessionName
A unique name for this test session to be used as a key for
this test session on the Control-Client.
senderIp
The IP address of the Session-Sender device, which is to be
placed in the source IP address field of the IP header in
TWAMP UDP test packets belonging to this test session. This
value will be used to populate the sender address field of
the Request-TW-Session message.
senderUdpPort
The UDP port number that is to be used by the Session-Sender
for this test session. A value of zero indicates that the
Control-Client will auto-allocate a UDP port for this test
session. This value is advertized in the sender port field
of the Request-TW-session message.
reflectorIp
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The IP address belonging to the remote Session-Reflector
device to which the TWAMP test session will be initiated.
This value will be used to populate the receiver address
field of the Request-TW-Session message.
reflectorUdpPort
This parameter defines the UDP port number that will be used
by the Session-Reflector for this test session. This value
will be placed in the receiver port field of the Request-TW-
Session message.
timeout The length of time (in seconds) that the Session-Reflector
should continue to respond to packets belonging to this
session after a Stop-Sessions control message has been
received ([RFC5357], Section 3.8). This value will be placed
in the timeout field of the Request-TW-Session message.
paddingLength
The number of bytes of padding that will be added to the UDP
test packets generated by the Session-Sender. This value
will be placed in the Padding Length field of the Request-TW-
Session message [RFC6038].
startTime
Time when the session is to be started (but not before the
Start-Sessions command is issued). This value is placed in
the Start Time field of the Request-TW-Session message. A
value of 0 indicates that the session will be started as soon
as the Start-Sessions message is received.
repeat and repeatInterval
These two values together are used to determine if the test
session is to be run repeatedly. Once a test session has
completed, the repeat parameter is checked. If the value
indicates that this test session is to run again, then the
parent control connection for this test session is restarted
- and negotiates a new instance of this test session. This
may happen immediately after the test session completes (if
the repeatInterval is set to 0). Otherwise, the Control-
Client will wait for the number of minutes specified in the
repeatInterval before negotiating the new instance of this
test session.
pmIndex Numerical index value of a Registered Metric in the
Performance Metric Registry [I-D.ietf-ippm-metric-registry].
Output Statistics will be specified in the Registry entry.
The following twampSessionRequest parameters are read-only:
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testSessionState
The test session state can be either accepted or indicate the
respective error code.
sid The SID allocated by the Server for this test session, and
communicated back to the Control-Client in the SID field of
the Accept-Session message; see Section 4.3 of [RFC6038].
4.2. Server
The twampServer container (see Figure 4) holds items that are related
to the configuration of the TWAMP Server logical entity (recall
Figure 1).
+------------------+
| twampServer |
+------------------+
| serverAdminState | 1..* +-----------+
| serverTcpPort |<>------| keyChain |
| servwait | +-----------+
| dscp | | keyID |
| count | | secretKey |
| maxCount | +-----------+
| modes |
| salt {ro} | 0..* +--------------------------------+
| serverIv {ro} |<>------| twampServerCtrlConnection |
| challenge {ro} | +--------------------------------+
+------------------+ | clientIp {ro} |
| clientTcpPort {ro} |
| serverIp {ro} |
| serverTcpPort {ro} |
| serverCtrlConnectionState {ro} |
| dscp {ro} |
| selectedMode {ro} |
| keyID {ro} |
| dkLen {ro} |
| count {ro} |
| maxCount {ro} |
+--------------------------------+
Figure 4: TWAMP Server UML class diagram
A device operating in the Server role cannot configure attributes on
a per control connection basis, as it has no foreknowledge of what
incoming TWAMP control connections it will receive. As such, any
parameter that the Server might want to apply to an incoming control
connection must be configured at the overall Server level, and will
then be applied to all incoming TWAMP control connections.
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Each twampServer container holds a list named keyChain which relates
KeyIDs with the respective secret keys. As mentioned in Section 4.1,
both the Server and the Control-Client use the same mappings from
KeyIDs to shared secrets. The Server, being prepared to conduct
sessions with more than one Control-Client, uses KeyIDs to choose the
appropriate secret key; a Control-Client would typically have
different secret keys for different Servers. keyId is a UTF-8 string,
up to 80 octets in length (if the string is shorter, it is padded
with zero octets), that tells the Server which shared secret the
Control-Client wishes to use to authenticate or encrypt.
Each incoming control connection that is active on the Server will be
represented by an instance of a twampServerCtrlConnection object.
All items in the twampServerCtrlConnection object are read-only.
The twampServer container items are as follows:
serverAdminState
This administrative parameter controls whether the device is
allowed to operate as a TWAMP Server. As defined in
[RFC5357] the roles of Server and Session-Reflector can be
played by the same host; recall Figure 2. For a host
operating in this manner, this parameter controls whether the
device is allowed to respond to TWAMP control and test
sessions.
serverTcpPort
This parameter defines the well known TCP port number that is
used by TWAMP. The Server will listen on this port for
incoming TWAMP control connections. Although this is defined
as a fixed value (862) in [RFC5357], there are several
realizations of TWAMP in the field that were implemented
before this well-known port number was allocated. These
early implementations allowed the port number to be
configured. This parameter is therefore provided for
backward compatibility reasons.
servwait
TWAMP Control (TCP) session timeout, in seconds.
dscp The DSCP value to be placed in the TCP header of TWAMP-
Control packets generated by the Server.
count Parameter used in deriving a key from a shared secret as
described in Section 3.1 of [RFC4656], and are communicated
to the Control-client as part of Server Greeting message.
Count MUST be a power of 2. Count MUST be at least 1024.
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Count SHOULD be increased as more computing power becomes
common.
maxCount
If an attacking system sets the maximum value in Count
(2**32), then the system under attack would stall for a
significant period of time while it attempts to generate
keys. Therefore, TWAMP-compliant systems SHOULD have a
configuration control to limit the maximum Count value. The
default maximum Count value SHOULD be 32768.
modes
The bit mask of TWAMP Modes this Server instance is willing
to support; see IANA TWAMP Modes Registry. Each bit position
set represents a mode; see TWAMP-Modes at
http://www.iana.org/assignments/twamp-parameters/twamp-
parameters.xhtml. Note: Modes requiring Authentication or
Encryption MUST include the related attributes.
The following parameters are read-only:
salt A parameter used in deriving a key from a shared secret as
described in Section 3.1 of [RFC4656]. Salt MUST be
generated pseudo-randomly (independently of anything else in
the RFC) and is communicated to the Control-Client as part of
the Server greeting message.
serverIv
The Server Initialization Vector (IV) is generated randomly
by the server.
challenge
Challenge is a random sequence of octets generated by the
server. As described in Section 4.1 challenge is used by the
Control-Client to prove possession of a shared secret.
There SHALL be one instance of twampServerCtrlConnection per incoming
TWAMP TCP Control connection that is received and active on the
Server device. All items in the twampServerCtrlConnection are read-
only. Each instance of twampServerCtrlConnection uses the following
4-tuple as its unique key: clientIp, clientTcpPort, serverIp,
serverTcpPort.
The twampServerCtrlConnection container items are all read-only:
clientIp
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The IP address on the remote Control-Client device, which is
the source IP address used in the TWAMP TCP control packets
belonging to this control connection.
clientTcpPort
The source TCP port used in the TWAMP TCP control packets
belonging to this control connection.
serverIp
The IP address of the local Server device, which is the
destination IP address used in the TWAMP TCP control packets
belonging to this control connection.
serverTcpPort
The destination TCP port used in the TWAMP TCP control
packets belonging to this control connection. This will
usually be the same value as is configured under twampServer.
However, in the event that the user re-configured
twampServer:serverTcpPort after this control connection was
initiated, this value will indicate the serverTcpPort that is
actually in use for this control connection.
serverCtrlConnectionState
The Server control connection state can be active or
SERVWAIT.
dscp
The DSCP value used in the header of the TCP control packets
sent by the Server for this control connection. This will
usually be the same value as is configured for
twampServer:dscp under the twampServer. However, in the
event that the user re-configures twampServer:dscp after this
control connection is already in progress, this read-only
value will show the actual dscp value in use by this control
connection.
selectedMode
The mode that was chosen for this control connection as set
in the Mode field of the Set-Up-Response message.
keyId
The keyId value that is in use by this control connection.
KeyID a UTF-8 string, up to 80 octets in length (if the
string is shorter, it is padded with zero octets). The
Control-Client selects the keyID for the control connection.
dkLen
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The dkLen value that is in use by this control connection.
This will usually be the same value as is configured under
twampServer. However, in the event that the user re-
configured twampServer:dkLen after this control connection is
already in progress, this read-only value will show the
actual dkLen that is in use for this control connection.
count
The count value that is in use by this control connection.
This will usually be the same value as is configured under
twampServer. However, in the event that the user re-
configured twampServer:count after this control connection is
already in progress, this read-only value will show the
actual count that is in use for this control connection.
maxCount
The maxCount value that is in use by this control connection.
This will usually be the same value as is configured under
twampServer. However, in the event that the user re-
configured twampServer:maxCount after this control connection
is already in progress, this read-only value will show the
actual maxCount that is in use for this control connection.
4.3. Session-Sender
The twampSessionSender container, illustrated in Figure 5, holds
items that are related to the configuration of the TWAMP Session-
Sender logical entity.
There are no global configuration items that apply to the Session-
Sender entity as a whole.
There is one instance of twampSenderTestSession for each test session
for which packets are being sent.
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+--------------------+
| twampSessionSender |
+--------------------+ 0..* +-------------------------+
| |<>------| twampSenderTestSession |
+--------------------+ +-------------------------+
| testSessionName |
| ctrlConnectionName {ro} |
| dscp |
| dot1dPriority |
| fillMode |
| numberOfPackets |
| senderSessionState {ro} |
| sentPackets {ro} |
| rcvPackets {ro} |
| lastSentSeq {ro} |
| lastRcvSeq {ro} |
+-------------------------+
^
V
| 1
+--------------------+
| packetDistribution |
+--------------------+
| fixed / poisson |
+--------------------+
| |
+--------------------+ |
| fixedInterval | |
| fixedIntervalUnits | |
+--------------------+ |
+----------------------+
| lambda |
| lambdaUnits |
| maxInterval |
| truncationPointUnits |
+----------------------+
Figure 5: TWAMP Session-Sender UML class diagram
The twampSenderTestSession container items are:
testSessionName
A unique name for this test session to be used as a key for
this test session by the Session-Sender logical entity.
ctrlConnectionName
The name of the parent control connection that is responsible
for negotiating this test session.
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dscp The DSCP value to be placed in the UDP header of TWAMP-
Control packets generated by the Session-Sender.
dot1dPriority
Priority Code Point (PCP) value to place in the Ethernet
header of the TWAMP UDP test frames transmitted for this test
session.
fillMode
Indicates whether the padding added to the UDP test packets
will contain pseudo-random numbers, or whether it should
consist of all zeroes, as per Section 4.2.1 of [RFC5357].
numberOfPackets
The overall number of UDP test packets to be transmitted by
the Session-Sender for this test session.
packetDistribution
Defines whether test packets are to be transmitted with a
fixed interval between them, or whether a Poisson
distribution is to be used.
fixedInterval and fixedIntervalUnits
If packetDistribution is set to fixed, these two values are
used together to determine the fixed time to wait between
test packet transmissions for this test session.
fixedInterval is an unsigned floating point number, 8
significant digits. fixedIntervalUnits is one of seconds,
milliseconds, microseconds, nanoseconds.
lambda and lambdaUnits
If packetDistribution is Poisson, the lambda parameter
defines the average rate of packet transmission. lambda is an
unsigned floating point number, 8 significant digits.
lambdaUnits defines the units of lambda in reciprocal
seconds.
maxInterval
If packetDistribution is Poisson, then this parameter keeps a
stream active by setting a maximum time between packet
transmissions.
truncationPointUnits
One of seconds, milliseconds, microseconds, nanoseconds.
The following twampSenderTestSession parameters are read-only:
senderSessionState
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This read-only item can be either Active or Idle.
sentPackets
The number of UDP test packets belonging to this session that
have been transmitted by the Session-Sender.
rcvPackets
The number of UDP test packets belonging to this session that
have been received from the Session-Reflector. The round
trip loss for a test session can be calculated as sentPackets
- rcvPackets.
lastSentSeq
The value in the sequence number field of the last UDP test
packet transmitted for this test session. Sequence numbers
start from zero - so this should always be one less than the
sentPackets value.
lastRcvSeq
The value in the sequence number field of the last UDP test
packet received for this test session. In the case of packet
loss in the Session-Sender -> Session-Reflector direction,
this value minus the lastSentSeq will identify the number of
packets that were lost in the Session-Sender -> Session-
Reflector direction.
4.4. Session-Reflector
The twampSessionReflector container, illustrated in Figure 6, holds
items that are related to the configuration of the TWAMP Session-
Reflector logical entity.
A device operating in the Session-Reflector role cannot configure
attributes on a per-session basis, as it has no foreknowledge of what
incoming sessions it will receive. As such, any parameter that the
Session-Reflector might want to apply to an incoming test session
must be configured at the overall Session-Reflector level, and will
then be applied to all incoming sessions.
Each incoming test session that is active on the Session-Reflector
will be represented by an instance of a twampReflectorTestSession
object. All items in the twampReflectorTestSession object are read-
only.
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+-----------------------+
| twampSessionReflector |
+-----------------------+ 0..* +------------------------------------+
| refwait |<>------| twampReflectorTestSession |
+-----------------------+ +------------------------------------+
| sid {ro} |
| senderIp {ro} |
| senderUdpPort {ro} |
| reflectorIp {ro} |
| reflectorUdpPort {ro} |
| parentConnectionClientIp {ro} |
| parentConnectionClientTcpPort {ro} |
| parentConnectionServerIp {ro} |
| parentConnectionServerTcpPort {ro} |
| dscp {ro} |
| sentPackets {ro} |
| rcvPackets {ro} |
| lastSentSeq {ro} |
| lastRcvSeq {ro} |
+------------------------------------+
Figure 6: TWAMP Session-Reflector UML class diagram
The twampSessionReflector configuration items are:
refwait
The Session-Reflector MAY discontinue any session that has
been started when no packet associated with that session has
been received for REFWAIT seconds. The default value of
REFWAIT SHALL be 900 seconds, and this waiting time MAY be
configurable. This timeout allows a Session-Reflector to
free up resources in case of failure.
Instances of twampSessionReflector:twampReflectorTestSession are
indexed by a session identifier (SID). This is a value that is auto-
allocated by the Server as test session requests are received, and
communicated back to the Control-Client in the SID field of the
Accept-Session message; see Section 4.3 of [RFC6038].
When attempting to retrieve operational data for active test sessions
from a Session-Reflector device, the user will not know what sessions
are currently active on that device, or what SIDs have been auto-
allocated for these test sessions. If the user has network access to
the Control-Client device, then it is possible to read the data for
this session under
twampClient:twampClientCtrlConnection:twampSessionRequest and obtain
the SID (see Figure 3). The user may then use this SID value as an
index to retrieve an individual
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twampSessionReflector:twampReflectorTestSession instance on the
Session-Reflector device.
If the user has no network access to the Control-Client device, then
the only option is to retrieve all twampReflectorTestSession
instances from the Session-Reflector device. This could be
problematic if a large number of test sessions are currently active
on that device.
Each Session-Reflector test session contains the following 4-tuple:
{parentConnectionClientIp, parentConnectionClientTcpPort,
parentConnectionServerIp, parentConnectionServerTcpPort}. This
4-tuple corresponds to the equivalent 4-tuple {clientIp,
clientTcpPort, serverIp, serverTcpPort} in the
twampServerCtrlConnection object. This four4-tuple allows the user
to trace back from the test session to the parent control connection
that negotiated this test session.
All data under twampReflectorTestSession is read-only:
sid An auto-allocated identifier for this test session, that is
unique within the context of this Server/Session-Reflector
device only. This value will be communicated to the Control-
Client that requested the test session in the SID field of
the Accept-Session message.
senderIp
The IP address on the remote device, which is the source IP
address used in the TWAMP UDP test packets belonging to this
test session.
senderUdpPort
The source UDP port used in the TWAMP UDP test packets
belonging to this test session.
reflectorIp
The IP address of the local Session-Reflector device, which
is the destination IP address used in the TWAMP UDP test
packets belonging to this test session.
reflectorUdpPort
The destination UDP port used in the TWAMP UDP test packets
belonging to this test session.
parentConnectionClientIp
The IP address on the Control-Client device, which is the
source IP address used in the TWAMP TCP control packets
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belonging to the parent control connection that negotiated
this test session.
parentConnectionClientTcpPort
The source TCP port used in the TWAMP TCP control packets
belonging to the parent control connection that negotiated
this test session.
parentConnectionServerIp
The IP address of the Server device, which is the destination
IP address used in the TWAMP TCP control packets belonging to
the parent control connection that negotiated this test
session.
parentConnectionServerTcpPort
The destination TCP port used in the TWAMP TCP control
packets belonging to the parent control connection that
negotiated this test session.
dscp The DSCP value present in the UDP header of TWAMP test
packets belonging to this test session.
sentPackets
The number of UDP test response packets that have been sent
by the Session-Reflector for this test session.
rcvPackets
The number of UDP test packets that have been received by the
Session-Reflector for this test session. Since the Session-
Reflector should respond to every test packet it receives,
the sentPackets and rcvPackets values should always be
identical.
lastSentSeq
The value in the sequence number field of the last UDP test
response packet transmitted for this test session.
lastRcvSeq
The value in the sequence number field of the last UDP test
packet received for this test session.
5. Data Model
5.1. Tree Diagram
This section presents the TWAMP YANG data tree defined in this
document. Readers should keep in mind that the limit of 72
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characters per line forces us to introduce artificial line breaks in
some tree nodes.
module: twamp
+--rw twamp
+--rw twampClient {controlClient}?
| +--rw clientAdminState boolean
| +--rw modePreferenceChain* [priority]
| | +--rw priority uint16
| | +--rw mode? enumeration
| +--rw keyChain* [keyId]
| | +--rw keyId string
| | +--rw secretKey? string
| +--rw twampClientCtrlConnection* [ctrlConnectionName]
| +--rw ctrlConnectionName string
| +--rw clientIp? inet:ip-address
| +--rw serverIp? inet:ip-address
| +--rw serverTcpPort? inet:port-number
| +--rw dscp? inet:dscp
| +--rw keyId? string
| +--rw dkLen? uint32
| +--ro clientTcpPort? inet:port-number
| +--ro serverStartTime? uint64
| +--ro ctrlConnectionState? enumeration
| +--ro selectedMode? enumeration
| +--ro token? string
| +--ro clientIv? string
| +--rw twampSessionRequest* [testSessionName]
| +--rw testSessionName string
| +--rw senderIp? inet:ip-address
| +--rw senderUdpPort? inet:port-number
| +--rw reflectorIp? inet:ip-address
| +--rw reflectorUdpPort? inet:port-number
| +--rw timeout? uint64
| +--rw paddingLength? uint32
| +--rw startTime? uint64
| +--rw repeat? boolean
| +--rw repeatInterval? uint32
| +--rw pmIndex? uint16
| +--ro testSessionState? enumeration
| +--ro sid? string
+--rw twampServer {server}?
| +--rw serverAdminState boolean
| +--rw serverTcpPort? inet:port-number
| +--rw servwait? uint32
| +--rw dscp? inet:dscp
| +--rw count? uint32
| +--rw maxCount? uint32
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| +--rw modes? bits
| +--ro salt? string
| +--ro serverIv? string
| +--ro challenge? string
| +--rw keyChain* [keyId]
| | +--rw keyId string
| | +--rw secretKey? string
| +--ro twampServerCtrlConnection* \
[clientIp clientTcpPort serverIp serverTcpPort]
| +--ro clientIp inet:ip-address
| +--ro clientTcpPort inet:port-number
| +--ro serverIp inet:ip-address
| +--ro serverTcpPort inet:port-number
| +--ro serverCtrlConnectionState? enumeration
| +--ro dscp? inet:dscp
| +--ro selectedMode? enumeration
| +--ro keyId? string
| +--ro dkLen? uint32
| +--ro count? uint32
| +--ro maxCount? uint32
+--rw twampSessionSender {sessionSender}?
| +--rw twampSenderTestSession* [testSessionName]
| +--rw testSessionName string
| +--ro ctrlConnectionName? string
| +--rw dscp? inet:dscp
| +--rw dot1dPriority? uint8
| +--rw fillMode? enumeration
| +--rw numberOfPackets? uint32
| +--rw (packetDistribution)?
| | +--:(fixed)
| | | +--rw fixedInterval? uint32
| | | +--rw fixedIntervalUnits? enumeration
| | +--:(poisson)
| | +--rw lambda? uint32
| | +--rw lambdaUnits? uint32
| | +--rw maxInterval? uint32
| | +--rw truncationPointUnits? enumeration
| +--ro senderSessionState? enumeration
| +--ro sentPackets? uint32
| +--ro rcvPackets? uint32
| +--ro lastSentSeq? uint32
| +--ro lastRcvSeq? uint32
+--rw twampSessionReflector {sessionReflector}?
+--rw refwait? uint32
+--ro twampReflectorTestSession* \
[senderIp senderUdpPort reflectorIp reflectorUdpPort]
+--ro sid? string
+--ro senderIp inet:ip-address
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+--ro senderUdpPort inet:port-number
+--ro reflectorIp inet:ip-address
+--ro reflectorUdpPort inet:port-number
+--ro parentConnectionClientIp? inet:ip-address
+--ro parentConnectionClientTcpPort? inet:port-number
+--ro parentConnectionServerIp? inet:ip-address
+--ro parentConnectionServerTcpPort? inet:port-number
+--ro dscp? inet:dscp
+--ro sentPackets? uint32
+--ro rcvPackets? uint32
+--ro lastSentSeq? uint32
+--ro lastRcvSeq? uint32
5.2. YANG Module
This section presents the TWAMP YANG module defined in this document.
<CODE BEGINS> file "ietf-twamp@2015-03-06.yang"
module twamp {
namespace "urn:ietf:params:xml:ns:yang:ietf-twamp";
//namespace need to be assigned by IANA
prefix "twamp";
import ietf-inet-types {
prefix inet;
}
organization
"IETF IPPM (IP Performance Metrics) Working Group";
contact
"draft-cmzrjp-ippm-twamp-yang@tools.ietf.org";
description "TWAMP Data Model";
revision "2015-03-06" {
description "Initial version. RFC5357 is covered.
RFC5618, RFC5938 and RFC6038 are not covered.";
}
feature controlClient {
description "This feature relates to the device functions as the
TWAMP Control-Client.";
}
feature server {
description "This feature relates to the device functions as the
TWAMP Server.";
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}
feature sessionSender {
description "This feature relates to the device functions as the
TWAMP Session-Sender.";
}
feature sessionReflector {
description "This feature relates to the device functions as the
TWAMP Session-Reflector.";
}
grouping maintenanceStatistics {
leaf sentPackets {
config "false";
type uint32;
}
leaf rcvPackets {
config "false";
type uint32;
}
leaf lastSentSeq {
config "false";
type uint32;
}
leaf lastRcvSeq {
config "false";
type uint32;
}
}
container twamp {
container twampClient {
if-feature controlClient;
leaf clientAdminState {
mandatory "true";
type boolean;
description "Indicates whether this device is allowed to run
TWAMP to initiate control/test sessions";
}
list modePreferenceChain {
key "priority";
unique "mode";
leaf priority {
type uint16;
}
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leaf mode {
type enumeration {
enum unauthenticated {
value "1";
}
enum authenticated {
value "2";
}
enum encrypted {
value "4";
}
enum unauthtestencrpytcontrol {
value "8";
}
enum individualsessioncontrol {
value "16";
}
enum reflectoctets {
value "32";
}
enum symmetricalsize {
value "64";
}
}
}
}
list keyChain {
key "keyId";
leaf keyId {
type string {
length "1..80";
}
}
leaf secretKey {
type string;
}
}
list twampClientCtrlConnection {
key "ctrlConnectionName";
leaf ctrlConnectionName {
type "string";
description "A unique name used as a key to identify this
individual TWAMP control connection on the
Control-Client device.";
}
leaf clientIp {
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type inet:ip-address;
}
leaf serverIp {
config "true";
type inet:ip-address;
}
leaf serverTcpPort {
type inet:port-number;
}
leaf dscp{
type inet:dscp;
description "The DSCP value to be placed in the IP header
of the TWAMP TCP Control packets generated
by the Control-Client";
}
leaf keyId {
type string {
length "1..80";
}
}
leaf dkLen {
type uint32;
}
leaf clientTcpPort {
config "false";
type inet:port-number;
}
leaf serverStartTime {
config "false";
type uint64;
}
leaf ctrlConnectionState {
config "false";
type enumeration {
enum active {
description "Control session is active.";
}
enum idle {
description "Control session is idle.";
}
}
}
leaf selectedMode {
config "false";
type enumeration {
enum unauthenticated {
value "1";
}
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enum authenticated {
value "2";
}
enum encrypted {
value "4";
}
enum unauthtestencrpytcontrol {
value "8";
}
enum individualsessioncontrol {
value "16";
}
enum reflectoctets {
value "32";
}
enum symmetricalsize {
value "64";
}
}
}
leaf token {
config "false";
type string {
length "1..64";
}
description "64 octets, containing the concatenation of a
16-octet challenge, a 16-octet AES Session-key used
for encryption, and a 32-octet HMAC-SHA1 Session-key
used for authentication";
}
leaf clientIv{
config "false";
type string {
length "1..16";
}
description "16 octets, Client-IV is generated randomly
by the Control-Client.";
}
list twampSessionRequest {
key "testSessionName";
leaf testSessionName {
type "string";
}
leaf senderIp {
type inet:ip-address;
}
leaf senderUdpPort {
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type inet:port-number;
}
leaf reflectorIp {
type inet:ip-address;
}
leaf reflectorUdpPort {
type inet:port-number;
}
leaf timeout {
type uint64;
description "The time Session-Reflector MUST wait after
receiving a Stop-Session message";
}
leaf paddingLength {
type uint32{
range "64..1500";
}
description "The number of bytes of padding that should
be added to the UDP test packets generated by the
sender.";
}
leaf startTime {
type uint64;
}
leaf repeat {
type boolean;
}
leaf repeatInterval {
type uint32;
when "repeat='true'";
description "Repeat interval (in minutes)";
}
leaf pmIndex {
type uint16;
description "Numerical index value of a Registered
Metric in the Performance Metric Registry";
}
leaf testSessionState {
config "false";
type enumeration {
enum ok {
value 0;
description "Test session is accepted.";
}
enum failed {
value 1;
description "Failure, reason unspecified
(catch-all).";
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}
enum internalError {
value 2;
description "Internal error.";
}
enum notSupported {
value 3;
description "Some aspect of request is not
supported.";
}
enum permanentResLimit {
value 4;
description "Cannot perform request due to
permanent resource limitations.";
}
enum tempResLimit {
value 5;
description "Cannot perform request due to
temporary resource limitations.";
}
}
}
leaf sid{
config "false";
type string;
}
}
}
}
container twampServer{
if-feature server;
leaf serverAdminState{
type boolean;
mandatory "true";
description "Indicates whether this device is allowed to run
TWAMP to respond to control/test sessions";
}
leaf serverTcpPort {
type inet:port-number;
default "862";
}
leaf servwait {
type uint32 {
range 1..604800;
}
default 900;
description "SERVWAIT (TWAMP Control (TCP) session timeout),
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default value is 900";
}
leaf dscp {
type inet:dscp;
description "The DSCP value to be placed in the IP header
of the TWAMP TCP Control packets generated by the Server";
}
leaf count {
type uint32 {
range 1024..4294967295;
}
}
leaf maxCount {
type uint32 {
range 1024..4294967295;
}
default 32768;
}
leaf modes {
type bits {
bit unauthenticated {
position 0;
}
bit authenticated {
position 1;
}
bit encrypted {
position 2;
}
bit unauthtestencryptcontrol {
position 3;
}
bit individualsessioncontrol {
position 4;
}
bit reflectoctets {
position 5;
}
bit symmetricalsize {
position 6;
}
}
}
leaf salt{
config "false";
type string {
length "1..16";
}
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description "Salt MUST be generated pseudo-randomly";
}
leaf serverIv {
config "false";
type string {
length "1..16";
}
description "16 octets, Server-IV is generated randomly
by the Control-Client.";
}
leaf challenge {
config "false";
type string {
length "1..16";
}
description "Challenge is a random sequence of octets
generated by the Server";
}
list keyChain {
key "keyId";
leaf keyId {
type string {
length "1..80";
}
}
leaf secretKey {
type string;
}
}
list twampServerCtrlConnection {
key "clientIp clientTcpPort serverIp serverTcpPort";
config "false";
leaf clientIp {
type inet:ip-address;
}
leaf clientTcpPort {
type inet:port-number;
}
leaf serverIp {
type inet:ip-address;
}
leaf serverTcpPort {
type inet:port-number;
}
leaf serverCtrlConnectionState {
type enumeration {
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enum "active";
enum "servwait";
}
}
leaf dscp {
type inet:dscp;
description "The DSCP value used in the header of the TCP
control packets sent by the Server for this control
connection. This will usually be the same value as is
configured for twampServer:dscp under the twampServer.
However, in the event that the user re-configures
twampServer:dscp after this control connection is already
in progress, this read-only value will show the actual
dscp value in use by this control connection.";
}
leaf selectedMode {
type enumeration {
enum unauthenticated {
value "1";
}
enum authenticated {
value "2";
}
enum encrypted {
value "4";
}
enum unauthtestencrpytcontrol {
value "8";
}
enum individualsessioncontrol {
value "16";
}
enum reflectoctets {
value "32";
}
enum symmetricalsize {
value "64";
}
}
description "The mode that was chosen for this control
connection as set in the Mode field of the Set-Up-Response
message.";
}
leaf keyId {
type string {
length "1..80";
}
description "The keyId value that is in use by this control
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connection.";
}
leaf dkLen {
type uint32;
description "The dkLen value that is in use by this control
connection. This will usually be the same value as is
configured under twampServer. In the event that the user
re-configured twampServer:dkLen after this control
connection is already in progress, this read-only value
will show the actual dkLen that is in use for this
control connection.";
}
leaf count {
type uint32 {
range 1024..4294967295;
}
description "The count value that is in use by this control
connection. This will usually be the same value as is
configured under twampServer. However, in the event that
the user re-configured twampServer:count after this control
connection is already in progress, this read-only value
will show the actual count that is in use for this
control connection.";
}
leaf maxCount {
type uint32 {
range 1024..4294967295;
}
description "The maxCount value that is in use by this
control connection. This will usually be the same value
as is configured under twampServer. However, in the event
that the user re-configured twampServer:maxCount after
this control connection is already in progress, this
read-only value will show the actual maxCount that is
in use for this control connection.";
}
}
}
container twampSessionSender {
if-feature sessionSender;
list twampSenderTestSession {
key "testSessionName";
leaf testSessionName {
type string;
description "A unique name for this test session to be used
as a key for this test session by the Session-Sender
logical entity.";
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}
leaf ctrlConnectionName {
config "false";
type "string";
description "The name of the parent control connection
that is responsible for negotiating this test session.";
}
leaf dscp {
type inet:dscp;
description "The DSCP value to be placed in the header of
TWAMP UDP test packets generated by the sender.";
}
leaf dot1dPriority {
type uint8 {
range "0..7";
}
}
leaf fillMode {
type enumeration {
enum zero;
enum random;
}
default zero;
}
leaf numberOfPackets {
type uint32;
description "The overall number of UDP test packets to be
transmitted by the sender for this test session.";
}
choice packetDistribution {
case fixed {
leaf fixedInterval {
type uint32;
}
leaf fixedIntervalUnits {
type enumeration {
enum seconds;
enum milliseconds;
enum microseconds;
enum nanoseconds;
}
}
}
case poisson {
leaf lambda {
type uint32;
}
leaf lambdaUnits {
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type uint32;
}
leaf maxInterval {
type uint32;
}
leaf truncationPointUnits {
type enumeration {
enum seconds;
enum milliseconds;
enum microseconds;
enum nanoseconds;
}
}
}
}
leaf senderSessionState {
config "false";
type enumeration {
enum setup {
description "Test session is active.";
}
enum failure {
description "Test session is idle.";
}
}
}
uses maintenanceStatistics;
}
}
container twampSessionReflector {
if-feature sessionReflector;
leaf refwait {
config "true";
type uint32 {
range 1..604800;
}
default 900;
description "REFWAIT(TWAMP test session timeout),
the default value is 900";
}
list twampReflectorTestSession {
key "senderIp senderUdpPort reflectorIp reflectorUdpPort";
config "false";
leaf sid {
type string;
}
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leaf senderIp {
type inet:ip-address;
}
leaf senderUdpPort {
type inet:port-number;
}
leaf reflectorIp {
type inet:ip-address;
}
leaf reflectorUdpPort {
type inet:port-number;
}
leaf parentConnectionClientIp {
type inet:ip-address;
}
leaf parentConnectionClientTcpPort {
type inet:port-number;
}
leaf parentConnectionServerIp {
type inet:ip-address;
}
leaf parentConnectionServerTcpPort {
type inet:port-number;
}
leaf dscp {
type inet:dscp;
description "The DSCP value placed in the header of TWAMP
UDP test packets generated by the Session-Sender.";
}
uses maintenanceStatistics;
}
}
}
}
<CODE ENDS>
6. Data Model Examples
This section presents a simple but complete example of configuring
all four entities in Figure 1, based on the YANG module specified in
Section 5. The example is illustrative in nature, but aims to be
self-contained, i.e. were it to be executed in a real TWAMP
implementation it would lead to a correctly configured test session.
A more elaborated example, which also includes authentication
parameters, is provided in Appendix A.
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6.1. Control-Client
The following configuration example shows a Control-Client with
clientAdminState enabled. In a real implementation this would permit
the Control-Client functional entity to initiate TWAMP control
connections and test sessions.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampClient>
<clientAdminState>True</clientAdminState>
</twampClient>
</twamp>
The following configuration example shows a Control-Client with two
instances of twampClientCtrlConnection, one called "RouterA" and
another called "RouterB". Each control connection is to a different
Server. The control connection named "RouterA" has two test session
requests. The control connection with name "RouterB" has no test
session requests.
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<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampClient>
<twampClientCtrlConnection>
<ctrlConnectionName>RouterA</ctrlConnectionName>
<clientIp>203.0.113.1</clientIp>
<serverIp>203.0.113.2</serverIp>
<twampSessionRequest>
<testSessionName>Test1</testSessionName>
<senderIp>10.1.1.1</senderIp>
<senderUdpPort>4000</senderUdpPort>
<reflectorIp>10.1.1.2</reflectorIp>
<reflectorUdpPort>5000</reflectorUdpPort>
<startTime>0</startTime>
</twampSessionRequest>
<twampSessionRequest>
<testSessionName>Test2</testSessionName>
<senderIp>203.0.113.1</senderIp>
<senderUdpPort>4001</senderUdpPort>
<reflectorIp>203.0.113.2</reflectorIp>
<reflectorUdpPort>5001</reflectorUdpPort>
<startTime>0</startTime>
</twampSessionRequest>
</twampClientCtrlConnection>
<twampClientCtrlConnection>
<ctrlConnectionName>RouterB</ctrlConnectionName>
<clientIp>203.0.113.1</clientIp>
<serverIp>203.0.113.3</serverIp>
</twampClientCtrlConnection>
</twampClient>
</twamp>
6.2. Server
This configuration example shows a Server with serverAdminState
enabled, which permits the device to respond to TWAMP control
connections and test sessions.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampServer>
<serverAdminState>True</serverAdminState>
</twampServer>
</twamp>
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The following example presents a Server with the control connection
corresponding to the control connection name (ctrlConnectionName)
"RouterA" presented in Section 6.1.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampServer>
<twampServerCtrlConnection>
<clientIp>203.0.113.1</clientIp>
<clientTcpPort>16341</clientTcpPort>
<serverIp>203.0.113.2</serverIp>
<serverTcpPort>862</serverTcpPort>
<serverCtrlConnectionState>active</serverCtrlConnectionState>
</twampServerCtrlConnection>
</twampServer>
</twamp>
6.3. Session-Sender
The following configuration example shows a Session-Sender with the
two test sessions presented earlier in Section 6.1.
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<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampSessionSender>
<twampSenderTestSession>
<testSessionName>Test1</testSessionName>
<ctrlConnectionName>RouterA</ctrlConnectionName> // read-only
<numberOfPackets>900</numberOfPackets>
<packetDistribution>
<fixedInterval>1</fixedInterval>
<fixedIntervalUnits>seconds</fixedIntervalUnits>
</packetDistribution>
</twampSenderTestSession>
<twampSenderTestSession>
<testSessionName>Test2</testSessionName>
<ctrlConnectionName>RouterA</ctrlConnectionName> // read-only
<numberOfPackets>900</numberOfPackets>
<packetDistribution>
<lambda>1</lambda>
<lambdaUnits>1</lambdaUnits>
<maxInterval>2</maxInterval>
<truncationPointunits>seconds</truncationPointunits>
</packetDistribution>
</twampSenderTestSession>
</twampSessionSender>
</twamp>
6.4. Session-Reflector
The following example shows the two Session-Reflector test sessions
corresponding to the test sessions presented in Section 6.3.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampSessionReflector>
<twampReflectorTestSession>
<sid>1232</sid>
<senderIp>10.1.1.1</senderIp>
<reflectorIp>10.1.1.2</reflectorIp>
<senderUdpPort>4000</senderUdpPort>
<reflectorUdpPort>5000</reflectorUdpPort>
<parentConnectionClientIp>
203.0.113.1
</parentConnectionClientIp>
<parentConnectionClientTcpPort>
16341
</parentConnectionClientTcpPort>
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<parentConnectionServerIp>
203.0.113.2
</parentConnectionServerIp>
<parentConnectionServerTcpPort>
862
</parentConnectionServerTcpPort>
<sentPackets>2</sentPackets>
<rcvPackets>2</rcvPackets>
<lastSentSeq>1</lastSentSeq>
<lastRcvSeq>1</lastRcvSeq>
</twampReflectorTestSession>
<twampReflectorTestSession>
<sid>178943</sid>
<senderIp>203.0.113.1</senderIp>
<reflectorIp>192.68.0.2</reflectorIp>
<senderUdpPort>4001</senderUdpPort>
<parentConnectionClientIp>
203.0.113.1
</parentConnectionClientIp>
<parentConnectionClientTcpPort>
16341
</parentConnectionClientTcpPort>
<parentConnectionServerIp>
203.0.113.2
</parentConnectionServerIp>
<parentConnectionServerTcpPort>
862
</parentConnectionServerTcpPort>
<reflectorUdpPort>5001</reflectorUdpPort>
<sentPackets>21</sentPackets>
<rcvPackets>21</rcvPackets>
<lastSentSeq>20</lastSentSeq>
<lastRcvSeq>20</lastRcvSeq>
</twampReflectorTestSession>
</twampSessionReflector>
</twamp>
7. Security Considerations
TBD
8. IANA Considerations
This document registers a URI in the IETF XML registry [RFC3688].
Following the format in [RFC3688], the following registration is
requested to be made.
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URI: urn:ietf:params:xml:ns:yang:ietf-twamp
Registrant Contact: The IPPM WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers a YANG module in the YANG Module Names
registry [RFC6020].
name: ietf-twamp
namespace: urn:ietf:params:xml:ns:yang:ietf-twamp
prefix: twamp
reference: RFC XXXX
9. Acknowledgements
Haoxing Shen contributed to the definition of the YANG module in
Section 5.
Kostas Pentikousis is partially supported by FP7 UNIFY
(http://fp7-unify.eu), a research project partially funded by the
European Community under the Seventh Framework Program (grant
agreement no. 619609). The views expressed here are those of the
authors only. The European Commission is not liable for any use that
may be made of the information in this document.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[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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[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
[RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement
Protocol (TWAMP) Reflect Octets and Symmetrical Size
Features", RFC 6038, October 2010.
10.2. Informative References
[I-D.elteto-ippm-twamp-mib]
Elteto, T. and G. Mirsky, "Two-Way Active Measurement
Protocol (TWAMP) Management Information Base (MIB)",
draft-elteto-ippm-twamp-mib-01 (work in progress), January
2014.
[I-D.ietf-ippm-metric-registry]
Bagnulo, M., Claise, B., Eardley, P., Morton, A., and A.
Akhter, "Registry for Performance Metrics", draft-ietf-
ippm-metric-registry-02 (work in progress), February 2015.
[I-D.ietf-netconf-restconf]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", draft-ietf-netconf-restconf-04 (work in
progress), January 2015.
[I-D.unify-nfvrg-challenges]
Szabo, R., Csaszar, A., Pentikousis, K., Kind, M., and D.
Daino, "Unifying Carrier and Cloud Networks: Problem
Statement and Challenges", draft-unify-nfvrg-challenges-00
(work in progress), October 2014.
[NSC] John, W., Pentikousis, K., et al., "Research directions in
network service chaining", Proc. SDN for Future Networks
and Services (SDN4FNS), Trento, Italy IEEE, November 2013.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
[RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the
Two-Way Active Measurement Protocol (TWAMP)", RFC 5618,
August 2009.
[RFC5938] Morton, A. and M. Chiba, "Individual Session Control
Feature for the Two-Way Active Measurement Protocol
(TWAMP)", RFC 5938, August 2010.
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[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", RFC
6241, June 2011.
[RFC7426] Haleplidis, E., Pentikousis, K., Denazis, S., Hadi Salim,
J., Meyer, D., and O. Koufopavlou, "Software-Defined
Networking (SDN): Layers and Architecture Terminology",
RFC 7426, January 2015.
Appendix A. Detailed Data Model Examples
In this section we extend the example presented in Section 6 by
configuring more fields such as authentication parameters, dscp
values and so on.
A.1. Control-Client
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampClient>
<clientAdminState>True</clientAdminState>
<modePreferenceChain>
<priority>0</priority>
<mode>0x00000002</mode>
</modePreferenceChain>
<modePreferenceChain>
<priority>1</priority>
<mode>0x00000001</mode>
</modePreferenceChain>
<keychain>
<keyid>KeyClient1ToRouterA</keyid>
<secretKey>secret1</secretKey>
</keychain>
<keychain>
<keyid>KeyForRouterB</keyid>
<secretKey>secret2</secretKey>
</keychain>
<twampClientCtrlConnection>
<ctrlConnectionName>RouterA</ctrlConnectionName>
<clientIp>203.0.113.1</clientIp>
<serverIp>203.0.113.2</serverIp>
<dscp>32</dscp>
<keyId>KeyClient1ToRouterA</keyId>
<dkLen>1024</dkLen>
<twampSessionRequest>
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<testSessionName>Test1</testSessionName>
<senderIp>10.1.1.1</senderIp>
<senderUdpPort>4000</senderUdpPort>
<reflectorIp>10.1.1.2</reflectorIp>
<reflectorUdpPort>5000</reflectorUdpPort>
<paddingLength>0</paddingLength>
<startTime>0</startTime>
<testSessionState>ok</testSessionState>
<sid>1232</sid>
</twampSessionRequest>
<twampSessionRequest>
<testSessionName>Test2</testSessionName>
<senderIp>203.0.113.1</senderIp>
<senderUdpPort>4001</senderUdpPort>
<reflectorIp>203.0.113.2</reflectorIp>
<reflectorUdpPort>5001</reflectorUdpPort>
<paddingLenth>32</paddingLenth>
<startTime>0</startTime>
<testSessionState>ok</testSessionState>
<sid>178943</sid>
</twampSessionRequest>
</twampClientCtrlConnection>
</twampClient>
</twamp>
A.2. Server
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<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampServer>
<serverAdminState>True</serverAdminState>
<servwait>1800</servwait>
<dscp>32</dscp>
<modes>0x00000003</modes>
<dkLen>1024</dkLen>
<count>256</count>
<keychain>
<keyid>KeyClient1ToRouterA</keyid>
<secretKey>secret1</secretKey>
</keychain>
<keychain>
<keyid>KeyClient10ToRouterA</keyid>
<secretKey>secret10</secretKey>
</keychain>
<twampServerCtrlConnection>
<clientIp>203.0.113.1</clientIp>
<clientTcpPort>16341</clientTcpPort>
<serverIp>203.0.113.2</serverIp>
<serverTcpPort>862</serverTcpPort>
<serverCtrlConnectionState>active</serverCtrlConnectionState>
<dscp>32</dscp>
<selectedMode>0x00000002</selectedMode>
<keyId>KeyClient1ToRouterA</keyId>
<count>1024</count>
</twampServerCtrlConnection>
</twampServer>
</twamp>
A.3. Session-Sender
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<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampSessionSender>
<twampSenderTestSession>
<testSessionName>Test1</testSessionName>
<ctrlConnectionName>RouterA</ctrlConnectionName> // read-only
<dscp>32</dscp>
<fillMode>zero</fillMode>
<numberOfPackets>900</numberOfPackets>
<packetDistribution>
<fixedInterval>1</fixedInterval>
<fixedIntervalUnits>seconds</fixedIntervalUnits>
</packetDistribution>
<senderSessionState>Active</senderSessionState>
<sentPackets>2</sentPackets>
<rcvPackets>2</rcvPackets>
<lastSentSeq>1</lastSentSeq>
<lastRcvSeq>1</lastRcvSeq>
</twampSenderTestSession>
<twampSenderTestSession>
<testSessionName>Test2</testSessionName>
<ctrlConnectionName>RouterA</ctrlConnectionName> // read-only
<dscp>32</dscp>
<fillMode>random</fillMode>
<numberOfPackets>900</numberOfPackets>
<packetDistribution>
<lambda>1</lambda>
<lambdaUnits>1</lambdaUnits>
<maxInterval>2</maxInterval>
<truncationPointunits>seconds</truncationPointunits>
</packetDistribution>
<senderSessionState>Active</senderSessionState>
<sentPackets>21</sentPackets>
<rcvPackets>21</rcvPackets>
<lastSentSeq>20</lastSentSeq>
<lastRcvSeq>20</lastRcvSeq>
</twampSenderTestSession>
</twampSessionSender>
</twamp>
A.4. Session-Reflector
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twampSessionReflector>
<twampReflectorTestSession>
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<sid>1232</sid>
<senderIp>10.1.1.1</senderIp>
<reflectorIp>10.1.1.2</reflectorIp>
<senderUdpPort>4000</senderUdpPort>
<reflectorUdpPort>5000</reflectorUdpPort>
<parentConnectionClientIp>
203.0.113.1
</parentConnectionClientIp>
<parentConnectionClientTcpPort>
16341
</parentConnectionClientTcpPort>
<parentConnectionServerIp>
203.0.113.2
</parentConnectionServerIp>
<parentConnectionServerTcpPort>
862
</parentConnectionServerTcpPort>
<dscp>32</dscp>
<sentPackets>2</sentPackets>
<rcvPackets>2</rcvPackets>
<lastSentSeq>1</lastSentSeq>
<lastRcvSeq>1</lastRcvSeq>
</twampReflectorTestSession>
<twampReflectorTestSession>
<sid>178943</sid>
<senderIp>203.0.113.1</senderIp>
<reflectorIp>192.68.0.2</reflectorIp>
<senderUdpPort>4001</senderUdpPort>
<parentConnectionClientIp>
203.0.113.1
</parentConnectionClientIp>
<parentConnectionClientTcpPort>
16341
</parentConnectionClientTcpPort>
<parentConnectionServerIp>
203.0.113.2
</parentConnectionServerIp>
<parentConnectionServerTcpPort>
862
</parentConnectionServerTcpPort>
<reflectorUdpPort>5001</reflectorUdpPort>
<dscp>32</dscp>
<sentPackets>21</sentPackets>
<rcvPackets>21</rcvPackets>
<lastSentSeq>20</lastSentSeq>
<lastRcvSeq>20</lastRcvSeq>
</twampReflectorTestSession>
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</twampSessionReflector>
</twamp>
Authors' Addresses
Ruth Civil
Ciena Corporation
307 Legget Drive
Kanata, ON K2K 3C8
Canada
Email: gcivil@ciena.com
URI: www.ciena.com
Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
URI: http://home.comcast.net/~acmacm/
Lianshu Zheng
Huawei Technologies
China
Email: vero.zheng@huawei.com
Reshad Rahman
Cisco Systems
2000 Innovation Drive
Kanata, ON K2K 3E8
Canada
Email: rrahman@cisco.com
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Mahesh Jethanandani
Ciena Corporation
3939 North 1st Street
San Jose, CA 95134
USA
Email: mjethanandani@gmail.com
URI: www.ciena.com
Kostas Pentikousis (editor)
EICT GmbH
EUREF-Campus Haus 13
Torgauer Strasse 12-15
10829 Berlin
Germany
Email: k.pentikousis@eict.de
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