Internet DRAFT - draft-cmzrjp-ippm-twamp-yang
draft-cmzrjp-ippm-twamp-yang
IPPM WG R. Civil
Internet-Draft Ciena Corporation
Intended status: Standards Track A. Morton
Expires: April 21, 2016 AT&T Labs
L. Zheng
Huawei Technologies
R. Rahman
Cisco Systems
M. Jethanandani
Ciena Corporation
K. Pentikousis, Ed.
EICT
October 19, 2015
Two-Way Active Measurement Protocol (TWAMP) Data Model
draft-cmzrjp-ippm-twamp-yang-02
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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 21, 2016.
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 . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 18
4.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 21
5. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.1. YANG Tree Diagram . . . . . . . . . . . . . . . . . . . . 25
5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 27
6. Data Model Examples . . . . . . . . . . . . . . . . . . . . . 43
6.1. Control-Client . . . . . . . . . . . . . . . . . . . . . 43
6.2. Server . . . . . . . . . . . . . . . . . . . . . . . . . 44
6.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 45
6.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 46
7. Security Considerations . . . . . . . . . . . . . . . . . . . 47
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 48
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 48
10.1. Normative References . . . . . . . . . . . . . . . . . . 48
10.2. Informative References . . . . . . . . . . . . . . . . . 49
Appendix A. Detailed Data Model Examples . . . . . . . . . . . . 50
A.1. Control-Client . . . . . . . . . . . . . . . . . . . . . 51
A.2. Server . . . . . . . . . . . . . . . . . . . . . . . . . 52
A.3. Session-Sender . . . . . . . . . . . . . . . . . . . . . 53
A.4. Session-Reflector . . . . . . . . . . . . . . . . . . . . 54
Appendix B. TWAMP Operational Commands . . . . . . . . . . . . . 55
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 55
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1. Introduction
The Two-Way Active Measurement Protocol (TWAMP) [RFC5357] is used to
measure network performance parameters such as latency, bandwidth,
and packet loss by sending probe packets and measuring 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. This document addresses this gap by
formally specifying the TWAMP data model using YANG.
1.1. Motivation
In current TWAMP deployments, the lack of a standardized data model
limits the flexibility to dynamically instantiate TWAMP-based
measurements across equipment from different vendors. In large,
virtualized, and dynamically instantiated infrastructures where
network functions are placed according to orchestration algorithms as
discussed in [I-D.unify-nfvrg-challenges][I-D.unify-nfvrg-devops],
proprietary mechanisms for managing TWAMP measurements pose severe
limitations with respect to programmability.
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 in YANG the TWAMP data model. Section 6 lists illustrative
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examples which conform to the YANG data model specified in this
document. Appendix A elaborates these examples further.
2. Scope, Model, and Applicability
The purpose of this document is the specification of a vendor-
independent data model for TWAMP implementations.
Figure 1 illustrates a redrawn version of the TWAMP logical model
found in Section 1.2 of [RFC5357]. 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 Figure 1
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 per [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. Appendix B considers TWAMP operational commands,
which are also 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 number
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, for
example, the source UDP port number 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 number of test packets and the packet distribution to
be employed.
3.4. Session-Reflector
Each TWAMP Session-Reflector is associated with zero or more test
sessions. For each test session, the REFWAIT parameter (Section 4.2
of [RFC5357] 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 twamp-client 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. client-admin-
state) and items that are associated with individual control
connections initiated by the Control-Client entity (twamp-client-
ctrl-connection).
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+--------------------+
| twamp-client |
+--------------------+ 1..* +-----------------------+
| client-admin-state |<>----------------------| mode-preference-chain |
| | +-----------------------+
| | 1..* +------------+ | priority |
| |<>-----| key-chain | | mode |
+--------------------+ +------------+ +-----------------------+
^ | key-id |
V | secret-key |
| +------------+
| 0..*
+------------------------------+
| twamp-client-ctrl-connection |
+------------------------------+
| ctrl-connection-name |
| client-ip |
| server-ip |
| server-tcp-port | 0..* +-------------------------+
| dscp |<>-------| twamp-session-request |
| key-id | +-------------------------+
| max-count | | test-session-name |
| client-tcp-port {ro} | | sender-ip |
| server-start-time {ro} | | sender-udp-port |
| ctrl-connection-state {ro} | | reflector-ip |
| selected-mode {ro} | | reflector-udp-port |
| token {ro} | | timeout |
| client-iv {ro} | | padding-length |
+------------------------------+ | dscp |
| start-time |
+-------------+ 1 | repeat |
| pm-reg-list |------<>| repeat-interval |
+-------------+ | test-session-state {ro} |
| pm-index | | sid {ro} |
+-------------+ +-------------------------+
Figure 3: TWAMP Control-Client UML class diagram
The twamp-client container includes an administrative parameter
(client-admin-state) that controls whether the device is allowed to
initiate TWAMP control sessions.
The twamp-client container holds a list (mode-preference-chain) which
specifies the preferred Mode values according to their preferred
order of use, including the authentication and encryption Modes.
Specifically, mode-preference-chain lists each priority (expressed as
a 16-bit unsigned integer, where zero is the highest priority and
subsequent values monotonically increasing) with their corresponding
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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 mode-preference-
chain list. 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 twamp-client container holds a list named key-chain
which relates KeyIDs with the respective secret keys. Both the
Server and the Control-Client use the same mappings from KeyIDs to
shared secrets (key-id and secret-key in Figure 3, respectively).
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. The secret-key is the shared secret, an octet
string of arbitrary length whose interpretation as a text string is
unspecified. The key-id and secret-key encoding should follow
Section 9.4 of [RFC6020]. The derived key length (dkLen in
[RFC2898]) MUST be 128-bits for the AES Session-key used for
encryption and a 256-bit HMAC-SHA1 Session-key used for
authentication (see Section 6.10 of [RFC4656]).
Each twamp-client container also holds a list of twamp-client-ctrl-
connection, 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 twamp-client-ctrl-connection per TWAMP-
Control (TCP) connection that is to be initiated from this device.
The configuration items for twamp-client-ctrl-connection are:
ctrl-connection-name
A unique name used as a key to identify this individual TWAMP
control connection on the Control-Client device.
client-ip
The IP address of the local Control-Client device, to be
placed in the source IP address field of the IP header in
TWAMP-Control (TCP) packets belonging to this control
connection. If not configured, the device SHALL choose its
own source IP address.
server-ip
The IP address belonging to the remote Server device, which
the TWAMP-Control connection will be initiated to. This item
is mandatory.
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server-tcp-port
This parameter defines the TCP port number that is to be used
by this outgoing TWAMP-Control connection. Typically, this
is the well-known TWAMP port number (862) as per [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. The default
value is 862.
dscp The DSCP value to be placed in the TCP header of TWAMP-
Control packets generated by this Control-Client. The
default value is 0.
key-id
The key-id value that is selected for this TWAMP-Control
connection.
max-count
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 max-count value SHOULD be 32768.
The following twamp-client-ctrl-connection parameters are read-only:
client-tcp-port
The source TCP port number used in the TWAMP-Control packets
belonging to this control connection.
server-start-time
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.
ctrl-connection-state
The TWAMP-Control connection state can be either active or
idle.
selected-mode
The TWAMP 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).
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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
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].
client-iv
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 twamp-client-ctrl-connection holds a list of twamp-session-
request. twamp-session-request 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 (see Section 3.5 of [RFC5357]). The Control-Client is also
responsible for scheduling and results collection for TWAMP-Test
sessions, so twamp-session-request will also hold information related
these actions (e.g. pm-index, repeat-interval).
There SHALL be one instance of twamp-session-request for each TWAMP-
Test session that is to be negotiated by this TWAMP-Control
connection via a Request-TW-Session/Accept-Session exchange.
The configuration items for twamp-session-request are:
test-session-name
A unique name for this test session to be used for
identification of this TWAMP-Test session on the Control-
Client.
sender-ip
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-Test (UDP) packets belonging to this test session.
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This value will be used to populate the sender address field
of the Request-TW-Session message. If not configured, the
device SHALL choose its own source IP address.
sender-udp-port
The UDP port number that is to be used by the Session-Sender
for this TWAMP-Test session. A value of zero indicates that
the Control-Client SHALL auto-allocate a UDP port number for
this TWAMP-Test session. The configured (or auto-allocated)
value is advertized in the Sender Port field of the Request-
TW-session message (see also Section 3.5 of [RFC5357]). Note
that in the scenario where a device auto-allocates a UDP port
number for a session, and the repeat parameter for that
session indicates that it should be repeated, the device is
free to auto-allocate a different UDP port number when it
negotiates the next (repeated) iteration of this session.
reflector-ip
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. This item is
mandatory.
reflector-udp-port
This parameter defines the UDP port number that will be used
by the Session-Reflector for this TWAMP-Test session. This
value will be placed in the Receiver Port field of the
Request-TW-Session message. If this value is not set, the
device SHALL use the same port number as defined in the
server-tcp-port parameter of this twamp-session-request's
parent twamp-client-ctrl-connection.
timeout The length of time (in seconds) that the Session-Reflector
should continue to respond to packets belonging to this
TWAMP-Test session after a Stop-Sessions TWAMP-Control
message has been received ([RFC5357], Section 3.8). This
value will be placed in the Timeout field of the Request-TW-
Session message. The default value is 2 seconds.
padding-length
The number of bytes of padding that will be added to the
TWAMP-Test (UDP) packets generated by the Session-Sender.
This value will be placed in the Padding Length field of the
Request-TW-Session message ([RFC4656], Section 3.5).
dscp The DSCP value to be placed in the UDP header of TWAMP-Test
packets generated by the Session-Sender, and in the UDP
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header of the TWAMP-Test response packets generated by the
Session-Reflector for this test session. This value will be
placed in the Type-P Descriptor field of the Request-TW-
Session message ([RFC5357]).
start-time
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. The
default value of 0 indicates that the session will be started
as soon as the Start-Sessions message is received.
repeat and repeat-interval
These two values together are used to determine if the TWAMP-
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 TWAMP-Control connection for this test session is
restarted - and negotiates a new instance of this TWAMP-Test
session. This may occur immediately after the test session
completes (if the repeat-interval is set to 0). Otherwise,
the Control-Client will wait for the number of minutes
specified in the repeat-interval parameter before negotiating
the new instance of this TWAMP-Test session. The default
value of repeat is 0, indicating that once the session has
completed, it will not be renegotiated and restarted.
pm-reg-list
A list of one or more Performance Metric Registry Index
values (see [I-D.ietf-ippm-metric-registry], which
communicate packet stream characteristics and one or more
metrics to be measured. All members of the pm-reg-list MUST
have the same stream characteristics, such that they combine
to specify all metrics that shall be measured on a single
stream.
pm-index
One or more Numerical index values of a Registered Metric in
the Performance Metric Registry
[I-D.ietf-ippm-metric-registry] comprise the pm-reg-list.
Output statistics are specified in the corresponding Registry
entry.
The following twamp-session-request parameters are read-only:
test-session-state
The TWAMP-Test session state can be either accepted or
indicate the respective error code.
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sid The SID allocated by the Server for this TWAMP-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 twamp-server container (see Figure 4) holds items that are
related to the configuration of the TWAMP Server logical entity
(recall Figure 1).
+------------------ -+
| twamp-server |
+--------------------+
| server-admin-state | 1..* +------------+
| server-tcp-port |<>------| key-chain |
| servwait | +------------+
| dscp | | key-id |
| count | | secret-key |
| max-count | +------------+
| modes |
| | 0..* +-----------------------------------+
| |<>------| twamp-server-ctrl-connection |
+--------------------+ +-----------------------------------+
| client-ip {ro} |
| client-tcp-port {ro} |
| server-ip {ro} |
| server-tcp-port {ro} |
| server-ctrl-connection-state {ro} |
| dscp {ro} |
| selected-mode {ro} |
| key-id {ro} |
| count {ro} |
| max-count {ro} |
| salt {ro} |
| server-iv {ro} |
| challenge {ro} |
+-----------------------------------+
Figure 4: TWAMP Server UML class diagram
A device operating in the Server role cannot configure attributes on
a per TWAMP-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 twamp-server container holds a list named key-chain 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. key-id tells the
Server which shared-secret the Control-Client wishes to use for
authentication or encryption.
Each incoming control connection that is active on the Server will be
represented by an instance of a twamp-server-ctrl-connection object.
All items in the twamp-server-ctrl-connection object are read-only,
as we explain later in this section.
The twamp-server container items are as follows:
server-admin-state
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 sessions.
server-tcp-port
This parameter defines the well known TCP port number that is
used by TWAMP-Control. The Server will listen on this port
number 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. The default value is 862.
servwait
TWAMP-Control (TCP) session timeout, in seconds (([RFC5357],
Section 3.1)).
dscp The DSCP value to be placed in the IP header of TWAMP-Control
(TCP) packets generated by the Server. Section 3.1 of
[RFC5357] specifies that the server SHOULD use the DSCP value
from the Control-Client's TCP SYN. However, for practical
purposes TWAMP will typically be implemented using a general
purpose TCP stack provided by the underlying operating
system, and such a stack may not provide this information to
the user. Consequently, it is not always possible to
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implement the behavior described in [RFC5357] in an OS-
portable version of TWAMP. The default behavior if this item
is not set is to use the DSCP value from the Control-Client's
TCP SYN, as per Section 3.1 of [RFC5357].
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 the Server Greeting message.
count MUST be a power of 2. count MUST be at least 1024.
count SHOULD be increased as more computing power becomes
common.
max-count
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 max-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.
There SHALL be one instance of twamp-server-ctrl-connection per
incoming TWAMP-Control (TCP) connection that is received and active
on the Server device. All items in the twamp-server-ctrl-connection
are read-only. Each instance of twamp-server-ctrl-connection uses
the following 4-tuple as its unique key: client-ip, client-tcp-port,
server-ip, server-tcp-port.
The twamp-server-ctrl-connection container items are all read-only:
client-ip
The IP address on the remote Control-Client device, which is
the source IP address used in the TWAMP-Control (TCP) packets
belonging to this control connection.
client-tcp-port
The source TCP port number used in the TWAMP-Control (TCP)
packets belonging to this control connection.
server-ip
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The IP address of the local Server device, which is the
destination IP address used in the TWAMP-Control (TCP)
packets belonging to this control connection.
server-tcp-port
The destination TCP port number used in the TWAMP-Control
(TCP) packets belonging to this control connection. This
will usually be the same value as the server-tcp-port
configured under twamp-server. However, in the event that
the user re-configured twamp-server:server-tcp-port after
this control connection was initiated, this value will
indicate the server-tcp-port that is actually in use for this
control connection.
server-ctrl-connection-state
The Server TWAMP-Control connection state can be active or
SERVWAIT.
dscp
The DSCP value used in the IP header of the TWAMP-Control
(TCP) packets sent by the Server for this control connection.
This will usually be the same value as is configured in the
dscp parameter under the twamp-server container. However, in
the event that the user re-configures twamp-server:dscp after
this control connection is already in progress, this read-
only value will show the actual dscp value in use by this
TWAMP-Control connection.
selected-mode
The Mode that was chosen for this TWAMP-Control connection as
set in the Mode field of the Set-Up-Response message.
key-id
The KeyID value that is in use by this TWAMP-Control
connection. The Control-Client selects the key-id for the
control connection.
count
The count value that is in use by this TWAMP-Control
connection. This will usually be the same value as is
configured under twamp-server. However, in the event that
the user re-configured twamp-server:count after this control
connection is already in progress, this read-only value will
show the actual count that is in use for this TWAMP-Control
connection.
max-count
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The max-count value that is in use by this TWAMP-Control
connection. This will usually be the same value as is
configured under twamp-server. However, in the event that
the user re-configured twamp-server:max-count after this
control connection is already in progress, this read-only
value will show the actual max-count that is in use for this
control connection.
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.
server-iv
The Server Initialization Vector (IV) is generated randomly
by the Server.
challenge
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.
4.3. Session-Sender
The twamp-session-sender container, illustrated in Figure 5, holds
items that are related to the configuration of the TWAMP Session-
Sender logical entity.
The twamp-session-sender container includes an administrative
parameter (session-sender-admin-state) that controls whether the
device is allowed to initiate TWAMP test sessions.
There is one instance of twamp-sender-test-session for each TWAMP-
Test session for which packets are being sent.
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+----------------------------+
| twamp-session-sender |
+----------------------------+ 0..* +---------------------------+
| session-sender-admin-state |<>-----| twamp-sender-test-session |
+----------------------------+ +---------------------------+
| test-session-name |
| ctrl-connection-name {ro} |
| fill-mode |
| number-of-packets |
| sender-session-state {ro} |
| sent-packets {ro} |
| rcv-packets {ro} |
| last-sent-seq {ro} |
| last-rcv-seq {ro} |
+---------------------------+
^
V
| 1
+---------------------+
| packet-distribution |
+---------------------+
| periodic / poisson |
+---------------------+
| |
+-------------------------+ |
| periodic-interval | |
| periodic-interval-units | |
+-------------------------+ |
+------------------------+
| lambda |
| lambda-units |
| max-interval |
| truncation-point-units |
+------------------------+
Figure 5: TWAMP Session-Sender UML class diagram
The twamp-sender-test-session container items are:
test-session-name
A unique name for this TWAMP-Test session to be used for
identifying this test session by the Session-Sender logical
entity.
ctrl-connection-name
The name of the parent TWAMP-Control connection that is
responsible for negotiating this TWAMP-Test session.
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fill-mode
Indicates whether the padding added to the TWAMP-Test (UDP)
packets will contain pseudo-random numbers, or whether it
should consist of all zeroes, as per Section 4.2.1 of
[RFC5357].
number-of-packets
The overall number of TWAMP-Test (UDP) packets to be
transmitted by the Session-Sender for this test session.
packet-distribution
Defines whether TWAMP-Test (UDP) packets are to be
transmitted with a fixed interval between them, or whether a
Poisson distribution is to be used.
periodic-interval and periodic-interval-units
If packet-distribution is set to periodic, these two values
are used together to determine the period to wait between the
first bits of TWAMP-Test (UDP) packet transmissions for this
test session. periodic-interval-units is one of seconds,
milliseconds, microseconds, nanoseconds; see [RFC3432].
lambda and lambda-units
If packet-distribution is Poisson, the lambda parameter
determines the corresponding average rate of packet
transmission. lambda-units defines the units of lambda in
reciprocal seconds; see [RFC3432].
max-interval
If packet-distribution is Poisson, then this parameter keeps
a stream active by setting a maximum time between packet
transmissions.
truncation-point-units
One of seconds, milliseconds, microseconds, nanoseconds.
The following twamp-sender-test-session parameters are read-only:
sender-session-state
This read-only item can be either Active or Idle.
sent-packets
The number of TWAMP-Test (UDP) packets belonging to this
session that have been transmitted by the Session-Sender.
rcv-packets
The number of TWAMP-Test (UDP) packets belonging to this
session that have been received from the Session-Reflector.
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The round trip loss for a test session can be calculated as
sent-packets - rcv-packets.
last-sent-seq
The value in the sequence number field of the last TWAMP-Test
(UDP) packet transmitted for this test session. Sequence
numbers start from zero, so this should always be one less
than the sent-packets value.
last-rcv-seq
The value in the sequence number field of the last TWAMP-Test
(UDP) packet received for this test session. In the case of
packet loss in the Session-Sender to Session-Reflector
direction, this value minus the last-sent-seq will quantify
the number of packets that were lost in the Session-Sender to
Session-Reflector direction.
4.4. Session-Reflector
The twamp-session-reflector 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 TWAMP-Test
session must be configured at the overall Session-Reflector level,
and will then be applied to all incoming sessions.
The twamp-session-sender container includes an administrative
parameter (session-reflector-admin-state) that controls whether the
device is allowed to respond to incoming TWAMP test sessions. Each
incoming TWAMP-Test session that is active on the Session-Reflector
will be represented by an instance of a twamp-reflector-test-session
object. All items in the twamp-reflector-test-session object are
read-only.
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+----=--------------------------+
| twamp-session-reflector |
+-------------------------------+
| session-reflector-admin-state |
| refwait |
+-------------------------------+
^
V
|
| 0..*
+----------------------------------------+
| twamp-reflector-test-session |
+----------------------------------------+
| sid {ro} |
| sender-ip {ro} |
| sender-udp-port {ro} |
| reflector-ip {ro} |
| reflector-udp-port {ro} |
| parent-connection-client-ip {ro} |
| parent-connection-client-tcp-port {ro} |
| parent-connection-server-ip {ro} |
| parent-connection-server-tcp-port {ro} |
| dscp {ro} |
| sent-packets {ro} |
| rcv-packets {ro} |
| last-sent-seq {ro} |
| last-rcv-seq {ro} |
+----------------------------------------+
Figure 6: TWAMP Session-Reflector UML class diagram
The twamp-session-reflector 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 twamp-reflector-test-session are indexed by a session
identifier (sid). This value 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].
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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 twamp-client:twamp-client-ctrl-connection:twamp-
session-request:sid and obtain the SID (see Figure 3). The user may
then use this SID value as an index to retrieve an individual twamp-
session-reflector:twamp-reflector-test-session 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 twamp-reflector-test-session
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 TWAMP-Test session contains the following
4-tuple: {parent-connection-client-ip, parent-connection-client-tcp-
port, parent-connection-server-ip, parent-connection-server-tcp-
port}. This 4-tuple corresponds to the equivalent 4-tuple {client-ip,
client-tcp-port, server-ip, server-tcp-port} in the twamp-server-
ctrl-connection object. This 4-tuple allows the user to trace back
from the TWAMP-Test session to the (parent) TWAMP-Control connection
that negotiated this test session.
All data under twamp-reflector-test-session is read-only:
sid An auto-allocated identifier for this TWAMP-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.
sender-ip
The IP address on the remote device, which is the source IP
address used in the TWAMP-Test (UDP) packets belonging to
this test session.
sender-udp-port
The source UDP port used in the TWAMP-Test packets belonging
to this test session.
reflector-ip
The IP address of the local Session-Reflector device, which
is the destination IP address used in the TWAMP-Test (UDP)
packets belonging to this test session.
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reflector-udp-port
The destination UDP port number used in the TWAMP-Test (UDP)
test packets belonging to this test session.
parent-connection-client-ip
The IP address on the Control-Client device, which is the
source IP address used in the TWAMP-Control (TCP) packets
belonging to the parent control connection that negotiated
this test session.
parent-connection-client-tcp-port
The source TCP port number used in the TWAMP TCP control
packets belonging to the parent control connection that
negotiated this test session.
parent-connection-server-ip
The IP address of the Server device, which is the destination
IP address used in the TWAMP-Control (TCP) packets belonging
to the parent control connection that negotiated this test
session.
parent-connection-server-tcp-port
The destination TCP port number used in the TWAMP-Control
(TCP) packets belonging to the parent control connection that
negotiated this test session.
dscp The DSCP value present in the IP header of TWAMP-Test (UDP)
packets belonging to this test session.
sent-packets
The number of TWAMP-Test (UDP) response packets that have
been sent by the Session-Reflector for this test session.
rcv-packets
The number of TWAMP-Test (UDP) 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 sent-packets and rcv-packets values
should always be identical.
last-sent-seq
The value in the sequence number field of the last TWAMP-Test
(UDP) response packet transmitted for this test session.
last-rcv-seq
The value in the sequence number field of the last TWAMP-Test
(UDP) packet received for this test session.
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5. Data Model
This section formally specifies the TWAMP data model using YANG.
5.1. YANG Tree Diagram
This section presents a simplified graphical representation of the
TWAMP data model using a YANG tree diagram. Readers should keep in
mind that the limit of 72 characters per line forces us to introduce
artificial line breaks in some tree diagram nodes.
module: ietf-twamp
+--rw twamp
+--rw twamp-client! {control-client}?
| +--rw client-admin-state boolean
| +--rw mode-preference-chain* [priority]
| | +--rw priority uint16
| | +--rw mode? mode
| +--rw key-chain* [key-id]
| | +--rw key-id string
| | +--rw secret-key? string
| +--rw twamp-client-ctrl-connection* [ctrl-connection-name]
| +--rw ctrl-connection-name string
| +--rw client-ip? inet:ip-address
| +--rw server-ip inet:ip-address
| +--rw server-tcp-port? inet:port-number
| +--rw dscp? inet:dscp
| +--rw key-id? string
| +--rw max-count? uint32
| +--ro client-tcp-port? inet:port-number
| +--ro server-start-time? uint64
| +--ro ctrl-connection-state? ctrl-connection-state
| +--ro selected-mode? mode
| +--ro token? binary
| +--ro client-iv? binary
| +--rw twamp-session-request* [test-session-name]
| +--rw test-session-name string
| +--rw sender-ip? inet:ip-address
| +--rw sender-udp-port? inet:port-number
| +--rw reflector-ip inet:ip-address
| +--rw reflector-udp-port? inet:port-number
| +--rw timeout? uint64
| +--rw padding-length? uint32
| +--rw dscp? inet:dscp
| +--rw start-time? uint64
| +--rw repeat? uint32
| +--rw repeat-interval? uint32
| +--rw pm-reg-list* [pm-index]
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| | +--rw pm-index uint16
| +--ro test-session-state? test-session-state
| +--ro sid? string
+--rw twamp-server! {server}?
| +--rw server-admin-state boolean
| +--rw server-tcp-port? inet:port-number
| +--rw servwait? uint32
| +--rw dscp? inet:dscp
| +--rw count? uint32
| +--rw max-count? uint32
| +--rw modes? mode
| +--rw key-chain* [key-id]
| | +--rw key-id string
| | +--rw secret-key? string
| +--ro twamp-server-ctrl-connection* \
[client-ip client-tcp-port \
server-ip server-tcp-port]
| +--ro client-ip inet:ip-address
| +--ro client-tcp-port inet:port-number
| +--ro server-ip inet:ip-address
| +--ro server-tcp-port inet:port-number
| +--ro server-ctrl-connection-state? \
server-ctrl-connection-state
| +--ro dscp? inet:dscp
| +--ro selected-mode? mode
| +--ro key-id? string
| +--ro count? uint32
| +--ro max-count? uint32
| +--ro salt? binary
| +--ro server-iv? binary
| +--ro challenge? binary
+--rw twamp-session-sender {session-sender}?
| +--rw session-sender-admin-state boolean
| +--rw twamp-sender-test-session* [test-session-name]
| +--rw test-session-name string
| +--ro ctrl-connection-name? string
| +--rw fill-mode? fill-mode
| +--rw number-of-packets? uint32
| +--rw (packet-distribution)?
| | +--:(periodic)
| | | +--rw periodic-interval? uint32
| | | +--rw periodic-interval-units? units
| | +--:(poisson)
| | +--rw lambda? uint32
| | +--rw lambda-units? uint32
| | +--rw max-interval? uint32
| | +--rw truncation-point-units? units
| +--ro sender-session-state? sender-session-state
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| +--ro sent-packets? uint32
| +--ro rcv-packets? uint32
| +--ro last-sent-seq? uint32
| +--ro last-rcv-seq? uint32
+--rw twamp-session-reflector {session-reflector}?
+--rw session-reflector-admin-state boolean
+--rw refwait? uint32
+--ro twamp-reflector-test-session* \
[sender-ip sender-udp-port \
reflector-ip reflector-udp-port]
+--ro sid? string
+--ro sender-ip inet:ip-address
+--ro sender-udp-port inet:port-number
+--ro reflector-ip inet:ip-address
+--ro reflector-udp-port inet:port-number
+--ro parent-connection-client-ip? inet:ip-address
+--ro parent-connection-client-tcp-port? inet:port-number
+--ro parent-connection-server-ip? inet:ip-address
+--ro parent-connection-server-tcp-port? inet:port-number
+--ro dscp? inet:dscp
+--ro sent-packets? uint32
+--ro rcv-packets? uint32
+--ro last-sent-seq? uint32
+--ro last-rcv-seq? uint32
5.2. YANG Module
This section presents the YANG module for the TWAMP data model
defined in this document.
<CODE BEGINS> file "ietf-twamp@2015-10-19.yang"
module ietf-twamp {
namespace "urn:ietf:params:xml:ns:yang:ietf-twamp";
//namespace need to be assigned by IANA
prefix "ietf-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 "2015-10-19" {
description "01 version. RFC5357, RFC5618, RFC5938 and RFC6038
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is covered. draft-ietf-ippm-metric-registry is also considered";
reference "draft-cmzrjp-ippm-twamp-yang";
}
feature control-client {
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.";
}
feature session-sender {
description "This feature relates to the device functions as
the TWAMP Session-Sender.";
}
feature session-reflector {
description "This feature relates to the device functions as
the TWAMP Session-Reflector.";
}
typedef ctrl-connection-state {
type enumeration {
enum active {
description "Control session is active.";
}
enum idle {
description "Control session is idle.";
}
}
description "Control connection state";
}
typedef mode {
type bits {
bit unauthenticated {
position "0";
description "Unauthenticated";
}
bit authenticated {
position "1";
description "Authenticated";
}
bit encrypted {
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position "2";
description "Encrypted";
}
bit unauth-test-encrpyt-control {
position "3";
description "Mixed Security Mode per RFC 5618. Test
protocol security mode in Unauthenticated mode,
Control protocol in Encrypted mode.";
}
bit individual-session-control {
position "4";
description "Individual session control per RFC5938.";
}
bit reflect-octets {
position "5";
description "Reflect octets capability per RFC6038.";
}
bit symmetrical-size {
position "6";
description "Symmetrical size per RFC6038.";
}
}
description "Authentication mode bit mask";
}
typedef test-session-state {
type enumeration {
enum ok {
value 0;
description "Test session is accepted.";
}
enum failed {
value 1;
description "Failure, reason unspecified (catch-all).";
}
enum internal-error {
value 2;
description "Internal error.";
}
enum not-supported {
value 3;
description "Some aspect of request is not supported.";
}
enum permanent-resource-limit {
value 4;
description "Cannot perform request due to
permanent resource limitations.";
}
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enum temp-resource-limit {
value 5;
description "Cannot perform request due to
temporary resource limitations.";
}
}
description "Test session state";
}
typedef server-ctrl-connection-state {
type enumeration {
enum "active" {
description "Active";
}
enum "servwait" {
description "Servwait";
}
}
description "Server control connection state";
}
typedef fill-mode {
type enumeration {
enum zero {
description "Zero";
}
enum random {
description "Random";
}
}
description "Indicates whether the padding added to the
UDP test packets will contain pseudo-random numbers, or
whether it should consist of all zeroes.";
}
typedef units {
type enumeration {
enum seconds {
description "Seconds";
}
enum milliseconds {
description "Milliseconds";
}
enum microseconds {
description "Microseconds";
}
enum nanoseconds {
description "Nanoseconds";
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}
}
description "Time units";
}
typedef sender-session-state {
type enumeration {
enum setup {
description "Test session is active.";
}
enum failure {
description "Test session is idle.";
}
}
description "Sender session state.";
}
grouping maintenance-statistics {
description "Maintenance statistics grouping";
leaf sent-packets {
type uint32;
config "false";
description "Packets sent";
}
leaf rcv-packets {
type uint32;
config "false";
description "Packets received";
}
leaf last-sent-seq {
type uint32;
config "false";
description "Last sent sequence number";
}
leaf last-rcv-seq {
type uint32;
config "false";
description "Last received sequence number";
}
}
container twamp {
description "Top level container";
container twamp-client {
if-feature control-client;
presence "twamp-client";
description "Twamp client container";
leaf client-admin-state {
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type boolean;
mandatory "true";
description "Indicates whether this device is allowed to run
TWAMP to initiate control sessions";
}
list mode-preference-chain {
key "priority";
unique "mode";
leaf priority {
type uint16;
description "priority";
}
leaf mode {
type mode;
description "Authentication mode bit mask";
}
description "Authentication mode preference";
}
list key-chain {
key "key-id";
leaf key-id {
type string {
length "1..80";
}
description "Key ID";
}
leaf secret-key {
type string;
description "Secret key";
}
description "Key chain";
}
list twamp-client-ctrl-connection {
key "ctrl-connection-name";
description "Twamp client control connections";
leaf ctrl-connection-name {
type string;
description "A unique name used as a key to identify this
individual TWAMP control connection on the
Control-Client device.";
}
leaf client-ip {
type inet:ip-address;
description "Client IP address";
}
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leaf server-ip {
type inet:ip-address;
mandatory "true";
description "Server IP address";
}
leaf server-tcp-port {
type inet:port-number;
default "862";
description "Server tcp port";
}
leaf dscp{
type inet:dscp;
default "0";
description "The DSCP value to be placed in the IP header
of the TWAMP TCP Control packets generated
by the Control-Client";
}
leaf key-id {
type string {
length "1..80";
}
description "Key ID";
}
leaf max-count {
type uint32 {
range 1024..4294967295;
}
default 32768;
description "Max count value.";
}
leaf client-tcp-port {
type inet:port-number;
config "false";
description "Client TCP port";
}
leaf server-start-time {
type uint64;
config "false";
description "The Start-Time advertized by the Server in
the Server-Start message";
}
leaf ctrl-connection-state {
type ctrl-connection-state;
config "false";
description "Control connection state";
}
leaf selected-mode {
type mode;
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config "false";
description "The TWAMP mode that the Control-Client has
chosen for this control connection as set in the Mode
field of the Set-Up-Response message";
}
leaf token {
type binary {
length "64";
}
config "false";
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 client-iv{
type binary {
length "16";
}
config "false";
description "16 octets, Client-IV is generated randomly
by the Control-Client.";
}
list twamp-session-request {
key "test-session-name";
description "Twamp session requests";
leaf test-session-name {
type string;
description "A unique name for this test session to be
used as a key for this test session on the
Control-Client.";
}
leaf sender-ip {
type inet:ip-address;
description "Sender IP address";
}
leaf sender-udp-port {
type inet:port-number;
description "Sender UDP port";
}
leaf reflector-ip {
type inet:ip-address;
mandatory "true";
description "Reflector IP address.";
}
leaf reflector-udp-port {
type inet:port-number;
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description "Reflector UDP port. If this value is not
set, the device shall use the same port number as
defined in the server-tcp-port parameter of this
twamp-session-request's
parent client-control-connection.";
}
leaf timeout {
type uint64;
default "2";
description "The time (in seconds)Session-Reflector MUST
wait after receiving a Stop-Session message.";
}
leaf padding-length {
type uint32{
range "64..4096";
}
description "The number of bytes of padding that should
be added to the UDP test packets generated by the
sender. Jumbo sized packets supported.";
}
leaf dscp {
type inet:dscp;
description "The DSCP value to be placed in the UDP
header of TWAMP-Test packets generated by the
Session-Sender, and in the UDP header of the TWAMP-Test
response packets generated by the Session-Reflector
for this test session.";
}
leaf start-time {
type uint64;
default "0";
description "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. The default value of 0
indicates that the session will be started as soon
as the Start-Sessions message is received.";
}
leaf repeat {
type uint32;
default "0";
description "Determines if the test session is to be
run repeatedly. The default value of repeat is 0,
indicating that once the session has completed, it
will not be renegotiated and restarted";
}
leaf repeat-interval {
when "../repeat!='0'" {
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description "When repeat is not 0, the test is to be
repeated";
}
type uint32;
description "Repeat interval (in minutes)";
}
list pm-reg-list {
key "pm-index";
leaf pm-index {
type uint16;
description "One or more Numerical index values of a
Registered Metric in the Performance Metric Registry";
}
description "A list of one or more pm-index values,
which communicate packet stream characteristics and one
or more metrics to be measured.";
}
leaf test-session-state {
type test-session-state;
config "false";
description "Test session state";
}
leaf sid{
type string;
config "false";
description "The SID allocated by the Server for
this test session";
}
}
}
}
container twamp-server{
if-feature server;
presence "twamp-server";
description "Twamp sever container";
leaf server-admin-state{
type boolean;
mandatory "true";
description "Indicates whether this device is allowed to run
TWAMP to respond to control sessions";
}
leaf server-tcp-port {
type inet:port-number;
default "862";
description "This parameter defines the well known TCP port
number that is used by TWAMP.";
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}
leaf servwait {
type uint32 {
range 1..604800;
}
default 900;
description "SERVWAIT (TWAMP Control (TCP) session timeout),
default value is 900";
}
leaf dscp {
type inet:dscp;
description "The DSCP value to be placed in the IP header of
TCP TWAMP-Control packets generated by the Server";
}
leaf count {
type uint32 {
range 1024..4294967295;
}
description "Parameter used in deriving a key from a
shared secret ";
}
leaf max-count {
type uint32 {
range 1024..4294967295;
}
default 32768;
description "Max count value.";
}
leaf modes {
type mode;
description "The bit mask of TWAMP Modes this Server
instance is willing to support.";
}
list key-chain {
key "key-id";
leaf key-id {
type string {
length "1..80";
}
description "Key IDs.";
}
leaf secret-key {
type string;
description "Secret keys.";
}
description "KeyIDs with the respective secret keys.";
}
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list twamp-server-ctrl-connection {
key "client-ip client-tcp-port server-ip server-tcp-port";
config "false";
description "Twamp server control connections";
leaf client-ip {
type inet:ip-address;
description "Client IP address";
}
leaf client-tcp-port {
type inet:port-number;
description "Client TCP port";
}
leaf server-ip {
type inet:ip-address;
description "Server IP address";
}
leaf server-tcp-port {
type inet:port-number;
description "Server TCP port";
}
leaf server-ctrl-connection-state {
type server-ctrl-connection-state;
description "Server control connection state";
}
leaf dscp {
type inet:dscp;
description "The DSCP value used in the IP 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 twamp-server:dscp under the twamp-server.
However, in the event that the user re-configures
twamp-server: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 selected-mode {
type mode;
description "The mode that was chosen for this control
connection as set in the Mode field of the
Set-Up-Response message.";
}
leaf key-id {
type string {
length "1..80";
}
description "The key-id value that is in use by this
control connection.";
}
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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 twamp-server. However, in the event that
the user re-configured twamp-server:count after this
control connection is already in progress, this read-only
value will show the different count that is in use for
this control connection.";
}
leaf max-count {
type uint32 {
range 1024..4294967295;
}
description "The max-count value that is in use by this
control connection. This will usually be the same value
as is configured under twamp-server. However, in the
event that the user re-configured twamp-server:max-count
after this control connection is already in progress,
this read-only value will show the different max-count
that is in use for this control connection.";
}
leaf salt{
type binary {
length "16";
}
description "Salt MUST be generated pseudo-randomly";
}
leaf server-iv {
type binary {
length "16";
}
description "16 octets, Server-IV is generated randomly
by the Control-Client.";
}
leaf challenge {
type binary {
length "16";
}
description "Challenge is a random sequence of octets
generated by the Server";
}
}
}
container twamp-session-sender{
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if-feature session-sender;
description "Twamp session sender container";
leaf session-sender-admin-state {
type boolean;
mandatory "true";
description "Indicates whether this device is allowed to run
TWAMP to initiate test sessions";
}
list twamp-sender-test-session{
key "test-session-name";
description "Twamp sender test sessions";
leaf test-session-name {
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.";
}
leaf ctrl-connection-name {
type string;
config "false";
description "The name of the parent control connection
that is responsible for negotiating this test session.";
}
leaf fill-mode {
type fill-mode;
default zero;
description "Indicates whether the padding added to the
UDP test packets will contain pseudo-random numbers, or
whether it should consist of all zeroes.";
}
leaf number-of-packets {
type uint32;
description "The overall number of UDP test packets to be
transmitted by the sender for this test session.";
}
choice packet-distribution {
description "Packet distributions, poisson or periodic";
case periodic {
leaf periodic-interval {
type uint32;
description "Periodic interval";
}
leaf periodic-interval-units {
type units;
description "Periodic interval units";
}
}
case poisson {
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leaf lambda{
type uint32;
description "The average rate of
packet transmission.";
}
leaf lambda-units{
type uint32;
description "Lambda units.";
}
leaf max-interval{
type uint32;
description "maximum time between packet
transmissions.";
}
leaf truncation-point-units{
type units;
description "Truncation point units";
}
}
}
leaf sender-session-state {
type sender-session-state;
config "false";
description "Sender session state.";
}
uses maintenance-statistics;
}
}
container twamp-session-reflector {
if-feature session-reflector;
description "Twamp session reflector container";
leaf session-reflector-admin-state {
type boolean;
mandatory "true";
description "Indicates whether this device is allowed to run
TWAMP to respond to test sessions";
}
leaf refwait {
type uint32 {
range 1..604800;
}
default 900;
description "REFWAIT (TWAMP test session timeout),
the default value is 900";
}
list twamp-reflector-test-session {
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key "sender-ip sender-udp-port reflector-ip
reflector-udp-port";
config "false";
description "Twamp reflector test sessions";
leaf sid{
type string;
description "An auto-allocated identifier for this test
session, that is unique within the context of this
Server/Session-Reflector device only. ";
}
leaf sender-ip {
type inet:ip-address;
description "Sender IP address.";
}
leaf sender-udp-port {
type inet:port-number;
description "Sender UDP port.";
}
leaf reflector-ip {
type inet:ip-address;
description "Reflector IP address.";
}
leaf reflector-udp-port {
type inet:port-number;
description "Reflector UDP port.";
}
leaf parent-connection-client-ip {
type inet:ip-address;
description "Parent connction client IP address.";
}
leaf parent-connection-client-tcp-port {
type inet:port-number;
description "Parent connection client TCP port.";
}
leaf parent-connection-server-ip {
type inet:ip-address;
description "Parent connection server IP address.";
}
leaf parent-connection-server-tcp-port {
type inet:port-number;
description "Parent connection server TCP port";
}
leaf dscp {
type inet:dscp;
description "The DSCP value present in the IP header of
TWAMP UDP test packets belonging to this test session.";
}
uses maintenance-statistics;
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}
}
}
}
<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.
6.1. Control-Client
The following configuration example shows a Control-Client with
client-admin-state enabled. In a real implementation following
Figure 2 this would permit the initiation of TWAMP-Control
connections and TWAMP-Test sessions.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-client>
<client-admin-state>True</client-admin-state>
</twamp-client>
</twamp>
The following configuration example shows a Control-Client with two
instances of twamp-client-ctrl-connection, one called "RouterA" and
another called "RouterB". Each TWAMP-Control connection is to a
different Server. The control connection named "RouterA" has two
test session requests. The TWAMP-Control connection named "RouterB"
has no TWAMP-Test session requests.
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<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-client>
<twamp-client-ctrl-connection>
<ctrl-connection-name>RouterA</ctrl-connection-name>
<client-ip>203.0.113.1</client-ip>
<server-ip>203.0.113.2</server-ip>
<twamp-session-request>
<test-session-name>Test1</test-session-name>
<sender-ip>10.1.1.1</sender-ip>
<sender-udp-port>4000</sender-udp-port>
<reflector-ip>10.1.1.2</reflector-ip>
<reflector-udp-port>5000</reflector-udp-port>
<start-time>0</start-time>
</twamp-session-request>
<twamp-session-request>
<test-session-name>Test2</test-session-name>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>4001</sender-udp-port>
<reflector-ip>203.0.113.2</reflector-ip>
<reflector-udp-port>5001</reflector-udp-port>
<start-time>0</start-time>
</twamp-session-request>
</twamp-client-ctrl-connection>
<twamp-client-ctrl-connection>
<ctrl-connection-name>RouterB</ctrl-connection-name>
<client-ip>203.0.113.1</client-ip>
<server-ip>203.0.113.3</server-ip>
</twamp-client-ctrl-connection>
</twamp-client>
</twamp>
6.2. Server
This configuration example shows a Server with server-admin-state
enabled, which permits a device following Figure 2 to respond to
TWAMP-Control connections and TWAMP-Test sessions.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-server>
<server-admin-state>True</server-admin-state>
</twamp-server>
</twamp>
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The following example presents a Server with the TWAMP-Control
connection corresponding to the control connection name (ctrl-
connection-name) "RouterA" presented in Section 6.1.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-server>
<twamp-server-ctrl-connection>
<client-ip>203.0.113.1</client-ip>
<client-tcp-port>16341</client-tcp-port>
<server-ip>203.0.113.2</server-ip>
<server-tcp-port>862</server-tcp-port>
<server-ctrl-connection-state>
active
</server-ctrl-connection-state>
</twamp-server-ctrl-connection>
</twamp-server>
</twamp>
6.3. Session-Sender
The following configuration example shows a Session-Sender with the
two TWAMP-Test sessions presented in Section 6.1.
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<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-session-sender>
<twamp-sender-test-session>
<test-session-name>Test1</test-session-name>// read-only
<ctrl-connection-name>RouterA</ctrl-connection-name>
<number-of-packets>900</number-of-packets>
<packet-distribution>
<periodic-interval>1</periodic-interval>
<periodic-interval-units>seconds</periodic-interval-units>
</packet-distribution>
</twamp-sender-test-session>
<twamp-sender-test-session>
<test-session-name>Test2</test-session-name>
<ctrl-connection-name>
RouterA
</ctrl-connection-name> // read-only
<number-of-packets>900</number-of-packets>
<packet-distribution>
<lambda>1</lambda>
<lambda-units>1</lambda-units>
<max-interval>2</max-interval>
<truncation-point-units>seconds</truncation-point-units>
</packet-distribution>
</twamp-sender-test-session>
</twamp-session-sender>
</twamp>
6.4. Session-Reflector
The following example shows the two Session-Reflector TWAMP-Test
sessions corresponding to the test sessions presented in Section 6.3.
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-session-reflector>
<twamp-reflector-test-session>
<sid>1232</sid>
<sender-ip>10.1.1.1</sender-ip>
<reflector-ip>10.1.1.2</reflector-ip>
<sender-udp-port>4000</sender-udp-port>
<reflector-udp-port>5000</reflector-udp-port>
<parent-connection-client-ip>
203.0.113.1
</parent-connection-client-ip>
<parent-connection-client-tcp-port>
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16341
</parent-connection-client-tcp-port>
<parent-connection-server-ip>
203.0.113.2
</parent-connection-server-ip>
<parent-connection-server-tcp-port>
862
</parent-connection-server-tcp-port>
<sent-packets>2</sent-packets>
<rcv-packets>2</rcv-packets>
<last-sent-seq>1</last-sent-seq>
<last-rcv-seq>1</last-rcv-seq>
</twamp-reflector-test-session>
<twamp-reflector-test-session>
<sid>178943</sid>
<sender-ip>203.0.113.1</sender-ip>
<reflector-ip>192.68.0.2</reflector-ip>
<sender-udp-port>4001</sender-udp-port>
<parent-connection-client-ip>
203.0.113.1
</parent-connection-client-ip>
<parent-connection-client-tcp-port>
16341
</parent-connection-client-tcp-port>
<parent-connection-server-ip>
203.0.113.2
</parent-connection-server-ip>
<parent-connection-server-tcp-port>
862
</parent-connection-server-tcp-port>
<reflector-udp-port>5001</reflector-udp-port>
<sent-packets>21</sent-packets>
<rcv-packets>21</rcv-packets>
<last-sent-seq>20</last-sent-seq>
<last-rcv-seq>20</last-rcv-seq>
</twamp-reflector-test-session>
</twamp-session-reflector>
</twamp>
7. Security Considerations
TBD
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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.
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
We thank Gregory Mirsky, Kevin D'Souza, and Robert Sherman for their
thorough and constructive reviews, comments and text suggestions.
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,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
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[RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network
performance measurement with periodic streams", RFC 3432,
DOI 10.17487/RFC3432, November 2002,
<http://www.rfc-editor.org/info/rfc3432>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<http://www.rfc-editor.org/info/rfc3688>.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<http://www.rfc-editor.org/info/rfc4656>.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<http://www.rfc-editor.org/info/rfc5357>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.
[RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement
Protocol (TWAMP) Reflect Octets and Symmetrical Size
Features", RFC 6038, DOI 10.17487/RFC6038, October 2010,
<http://www.rfc-editor.org/info/rfc6038>.
10.2. Informative References
[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-05 (work in progress), October 2015.
[I-D.ietf-netconf-restconf]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", draft-ietf-netconf-restconf-08 (work in
progress), October 2015.
[I-D.unify-nfvrg-challenges]
Szabo, R., Csaszar, A., Pentikousis, K., Kind, M., Daino,
D., Qiang, Z., and H. Woesner, "Unifying Carrier and Cloud
Networks: Problem Statement and Challenges", draft-unify-
nfvrg-challenges-02 (work in progress), July 2015.
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[I-D.unify-nfvrg-devops]
Meirosu, C., Manzalini, A., Steinert, R., Marchetto, G.,
Papafili, I., Pentikousis, K., and S. Wright, "DevOps for
Software-Defined Telecom Infrastructures", draft-unify-
nfvrg-devops-03 (work in progress), October 2015.
[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.
[RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography
Specification Version 2.0", RFC 2898,
DOI 10.17487/RFC2898, September 2000,
<http://www.rfc-editor.org/info/rfc2898>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005,
<http://www.rfc-editor.org/info/rfc4086>.
[RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the
Two-Way Active Measurement Protocol (TWAMP)", RFC 5618,
DOI 10.17487/RFC5618, August 2009,
<http://www.rfc-editor.org/info/rfc5618>.
[RFC5938] Morton, A. and M. Chiba, "Individual Session Control
Feature for the Two-Way Active Measurement Protocol
(TWAMP)", RFC 5938, DOI 10.17487/RFC5938, August 2010,
<http://www.rfc-editor.org/info/rfc5938>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
Defined Networking (SDN): Layers and Architecture
Terminology", RFC 7426, DOI 10.17487/RFC7426, January
2015, <http://www.rfc-editor.org/info/rfc7426>.
Appendix A. Detailed Data Model Examples
This appendix extends the example presented in Section 6 by
configuring more fields such as authentication parameters, dscp
values and so on.
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A.1. Control-Client
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-client>
<client-admin-state>True</client-admin-state>
<mode-preference-chain>
<priority>0</priority>
<mode>0x00000002</mode>
</mode-preference-chain>
<mode-preference-chain>
<priority>1</priority>
<mode>0x00000001</mode>
</mode-preference-chain>
<keychain>
<keyid>KeyClient1ToRouterA</keyid>
<secret-key>secret1</secret-key>
</keychain>
<keychain>
<keyid>KeyForRouterB</keyid>
<secret-key>secret2</secret-key>
</keychain>
<twamp-client-ctrl-connection>
<ctrl-connection-name>RouterA</ctrl-connection-name>
<client-ip>203.0.113.1</client-ip>
<server-ip>203.0.113.2</server-ip>
<dscp>32</dscp>
<key-id>KeyClient1ToRouterA</key-id>
<twamp-session-request>
<test-session-name>Test1</test-session-name>
<sender-ip>10.1.1.1</sender-ip>
<sender-udp-port>4000</sender-udp-port>
<reflector-ip>10.1.1.2</reflector-ip>
<reflector-udp-port>5000</reflector-udp-port>
<padding-length>0</padding-length>
<start-time>0</start-time>
<test-session-state>ok</test-session-state>
<sid>1232</sid>
</twamp-session-request>
<twamp-session-request>
<test-session-name>Test2</test-session-name>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>4001</sender-udp-port>
<reflector-ip>203.0.113.2</reflector-ip>
<reflector-udp-port>5001</reflector-udp-port>
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<paddingLenth>32</paddingLenth>
<start-time>0</start-time>
<test-session-state>ok</test-session-state>
<sid>178943</sid>
</twamp-session-request>
</twamp-client-ctrl-connection>
</twamp-client>
</twamp>
A.2. Server
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-server>
<server-admin-state>True</server-admin-state>
<servwait>1800</servwait>
<dscp>32</dscp>
<modes>0x00000003</modes>
<count>256</count>
<keychain>
<keyid>KeyClient1ToRouterA</keyid>
<secret-key>secret1</secret-key>
</keychain>
<keychain>
<keyid>KeyClient10ToRouterA</keyid>
<secret-key>secret10</secret-key>
</keychain>
<twamp-server-ctrl-connection>
<client-ip>203.0.113.1</client-ip>
<client-tcp-port>16341</client-tcp-port>
<server-ip>203.0.113.2</server-ip>
<server-tcp-port>862</server-tcp-port>
<server-ctrl-connection-state>
active
</server-ctrl-connection-state>
<dscp>32</dscp>
<selected-mode>0x00000002</selected-mode>
<key-id>KeyClient1ToRouterA</key-id>
<count>1024</count>
</twamp-server-ctrl-connection>
</twamp-server>
</twamp>
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A.3. Session-Sender
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-session-sender>
<twamp-sender-test-session>
<test-session-name>Test1</test-session-name> // read-only
<ctrl-connection-name>RouterA</ctrl-connection-name>
<dscp>32</dscp>
<fill-mode>zero</fill-mode>
<number-of-packets>900</number-of-packets>
<packet-distribution>
<periodic-interval>1</periodic-interval>
<periodic-interval-units>seconds</periodic-interval-units>
</packet-distribution>
<sender-session-state>Active</sender-session-state>
<sent-packets>2</sent-packets>
<rcv-packets>2</rcv-packets>
<last-sent-seq>1</last-sent-seq>
<last-rcv-seq>1</last-rcv-seq>
</twamp-sender-test-session>
<twamp-sender-test-session>
<test-session-name>Test2</test-session-name>
<ctrl-connection-name>
RouterA
</ctrl-connection-name> // read-only
<dscp>32</dscp>
<fill-mode>random</fill-mode>
<number-of-packets>900</number-of-packets>
<packet-distribution>
<lambda>1</lambda>
<lambda-units>1</lambda-units>
<max-interval>2</max-interval>
<truncation-point-units>seconds</truncation-point-units>
</packet-distribution>
<sender-session-state>Active</sender-session-state>
<sent-packets>21</sent-packets>
<rcv-packets>21</rcv-packets>
<last-sent-seq>20</last-sent-seq>
<last-rcv-seq>20</last-rcv-seq>
</twamp-sender-test-session>
</twamp-session-sender>
</twamp>
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A.4. Session-Reflector
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-session-reflector>
<twamp-reflector-test-session>
<sid>1232</sid>
<sender-ip>10.1.1.1</sender-ip>
<reflector-ip>10.1.1.2</reflector-ip>
<sender-udp-port>4000</sender-udp-port>
<reflector-udp-port>5000</reflector-udp-port>
<parent-connection-client-ip>
203.0.113.1
</parent-connection-client-ip>
<parent-connection-client-tcp-port>
16341
</parent-connection-client-tcp-port>
<parent-connection-server-ip>
203.0.113.2
</parent-connection-server-ip>
<parent-connection-server-tcp-port>
862
</parent-connection-server-tcp-port>
<dscp>32</dscp>
<sent-packets>2</sent-packets>
<rcv-packets>2</rcv-packets>
<last-sent-seq>1</last-sent-seq>
<last-rcv-seq>1</last-rcv-seq>
</twamp-reflector-test-session>
<twamp-reflector-test-session>
<sid>178943</sid>
<sender-ip>203.0.113.1</sender-ip>
<reflector-ip>192.68.0.2</reflector-ip>
<sender-udp-port>4001</sender-udp-port>
<parent-connection-client-ip>
203.0.113.1
</parent-connection-client-ip>
<parent-connection-client-tcp-port>
16341
</parent-connection-client-tcp-port>
<parent-connection-server-ip>
203.0.113.2
</parent-connection-server-ip>
<parent-connection-server-tcp-port>
862
</parent-connection-server-tcp-port>
<reflector-udp-port>5001</reflector-udp-port>
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<dscp>32</dscp>
<sent-packets>21</sent-packets>
<rcv-packets>21</rcv-packets>
<last-sent-seq>20</last-sent-seq>
<last-rcv-seq>20</last-rcv-seq>
</twamp-reflector-test-session>
</twamp-session-reflector>
</twamp>
Appendix B. TWAMP Operational Commands
This document is targeted at configuration details for TWAMP.
Operational actions such as how TWAMP sessions are started/stopped,
how results are retrieved, or stored results are cleared, and so on,
are not addressed by this configuration model and are out of scope of
this document.
TWAMP operational commands could be performed programmatically or
manually, e.g. using a command-line interface (CLI). With respect to
programmability, YANG can be used to define NETCONF Remote Procedure
Calls (RPC), therefore it would be possible to define RPC operations
for actions such as starting or stopping control or test sessions or
groups of sessions; retrieving results; clearing stored results, and
so on.
However, [RFC5357] does not attempt to describe such operational
actions, and it is likely that different TWAMP implementations could
support different sets of operational commands, with different
restrictions. Therefore, this document considers it the
responsibility of the individual implementation to define its
corresponding TWAMP operational commands data model.
Authors' Addresses
Ruth Civil
Ciena Corporation
307 Legget Drive
Kanata, ON K2K 3C8
Canada
Email: gcivil@ciena.com
URI: www.ciena.com
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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
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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