One document matched: draft-cmzrjp-ippm-twamp-yang-01.xml
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<rfc category="std" docName="draft-cmzrjp-ippm-twamp-yang-01"
ipr="trust200902">
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<front>
<title abbrev="TWAMP YANG Data Model">Two-Way Active Measurement Protocol
(TWAMP) Data Model</title>
<author fullname="Ruth Civil" initials="R." surname="Civil">
<organization>Ciena Corporation</organization>
<address>
<postal>
<street>307 Legget Drive</street>
<city>Kanata</city>
<region>ON</region>
<code>K2K 3C8</code>
<country>Canada</country>
</postal>
<email>gcivil@ciena.com</email>
<uri>www.ciena.com</uri>
</address>
</author>
<author fullname="Al Morton" initials="A." surname="Morton">
<organization>AT&T Labs</organization>
<address>
<postal>
<street>200 Laurel Avenue South</street>
<city>Middletown,</city>
<region>NJ</region>
<code>07748</code>
<country>USA</country>
</postal>
<phone>+1 732 420 1571</phone>
<facsimile>+1 732 368 1192</facsimile>
<email>acmorton@att.com</email>
<uri>http://home.comcast.net/~acmacm/</uri>
</address>
</author>
<author fullname="Lianshu Zheng" initials="L." surname="Zheng">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street/>
<city/>
<region/>
<code/>
<country>China</country>
</postal>
<email>vero.zheng@huawei.com</email>
</address>
</author>
<author fullname="Reshad Rahman" initials="R." surname="Rahman">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>2000 Innovation Drive</street>
<city>Kanata</city>
<region>ON</region>
<code>K2K 3E8</code>
<country>Canada</country>
</postal>
<email>rrahman@cisco.com</email>
</address>
</author>
<author fullname="Mahesh Jethanandani" initials="M" surname="Jethanandani">
<organization>Ciena Corporation</organization>
<address>
<postal>
<street>3939 North 1st Street</street>
<city>San Jose</city>
<region>CA</region>
<code>95134</code>
<country>USA</country>
</postal>
<email>mjethanandani@gmail.com</email>
<uri>www.ciena.com</uri>
</address>
</author>
<author fullname="Kostas Pentikousis" initials="K.P." role="editor"
surname="Pentikousis">
<organization abbrev="EICT">EICT GmbH</organization>
<address>
<postal>
<street>EUREF-Campus Haus 13</street>
<street>Torgauer Strasse 12-15</street>
<city>10829 Berlin</city>
<country>Germany</country>
</postal>
<email>k.pentikousis@eict.de</email>
</address>
</author>
<date year="2015"/>
<area>Transport</area>
<workgroup>IPPM WG</workgroup>
<abstract>
<t>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.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>The Two-Way Active Measurement Protocol (TWAMP) <xref
target="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.</t>
<section anchor="motivation" title="Motivation">
<t>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 <xref
target="I-D.unify-nfvrg-challenges"/><xref
target="I-D.unify-nfvrg-devops"/>, proprietary mechanisms for
managing TWAMP measurements pose severe limitations with respect to programmability.</t>
<t>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
<xref target="NSC"/> and programmable control and management planes
<xref target="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 <xref
target="RFC6020"/>.</t>
</section>
<section title="Terminology">
<t>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 <xref
target="RFC2119"/>.</t>
</section>
<section title="Document Organization">
<t>The rest of this document is organized as follows. <xref
target="scope"/> presents the scope and applicability of this
document. <xref target="structure"/> provides a high-level overview of
the TWAMP data model. <xref target="parameters"/> details the
configuration parameters of the data model and <xref target="module"/>
specifies in YANG the TWAMP data model. <xref target="examples"/>
lists illustrative examples which conform to the YANG data model
specified in this document. <xref target="AuthExample"/> elaborates
these examples further.</t>
</section>
</section>
<section anchor="scope" title="Scope, Model, and Applicability">
<t>The purpose of this document is the specification of a
vendor-independent data model for TWAMP implementations.</t>
<t><xref target="fig:scope"/> illustrates a redrawn version of the TWAMP
logical model found in Section 1.2 of <xref target="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 <xref target="RFC5357"/>,
unlabeled links in <xref target="fig:scope"/> are unspecified and may be
proprietary protocols.</t>
<figure anchor="fig:scope" title="Annotated TWAMP logical model">
<artwork><![CDATA[
[Fig. 3] [Fig. 4]
+----------------+ +--------+
| Control-Client | <-- TWAMP-Control --> | Server |
+----------------+ +--------+
^ ^
| |
V V
+----------------+ +-------------------+
| Session-Sender | <-- TWAMP-Test --> | Session-Reflector |
+----------------+ +-------------------+
[Fig. 5] [Fig. 6]
]]></artwork>
</figure>
<t>As per <xref target="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. <xref
target="fig:scope2"/> illustrates this simplified logical model and
indicates the interaction between the TWAMP configuration client and
server using, for instance, NETCONF <xref target="RFC6241"/> or RESTCONF
<xref target="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. <xref
target="OperationalCommands"/> considers TWAMP operational commands,
which are also outside the scope of this document.</t>
<figure anchor="fig:scope2" title="Simplified TWAMP model and protocols">
<artwork><![CDATA[
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 |
+-------------------+ +-------------------+
]]></artwork>
</figure>
</section>
<section anchor="structure" title="Data Model Overview">
<t>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.</t>
<t>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 <xref target="fig:scope"/>.</t>
<section anchor="twamp-client" title="Control-Client">
<t>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.</t>
<t>Each TWAMP Control-Client is associated with zero or more TWAMP
control connections. The main configuration parameters of each control
connection are: <list style="symbols">
<t>A name which can be used to uniquely identify at the
Control-Client a particular control connection. This name is
necessary 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.</t>
<t>The IP address of the interface the Control-Client will use for
connections</t>
<t>The IP address of the remote Server</t>
<t>Authentication and Encryption attributes such as KeyID, Token
and the Client Initialization Vector (Client-IV) <xref
target="RFC4656"/>.</t>
</list></t>
<t>Each TWAMP control connection, in turn, is associated with zero or
more test sessions. For each test session we note the following
configuration items: <list style="symbols">
<t>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.</t>
<t>The IP address and UDP port number of the Session-Sender of the
path under test by TWAMP</t>
<t>The IP address and UDP port number of the Session-Reflector of
said path</t>
<t>Information pertaining to the test packet stream, such as the
test starting time or whether the test should be repeated.</t>
</list></t>
</section>
<section anchor="twamp-server" title="Server">
<t>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.</t>
<t>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.</t>
</section>
<section anchor="twampSender" title="Session-Sender">
<t>There is one TWAMP Session-Sender instance for each test session
that is initiated from the sending device. Primary configuration
fields include: <list style="symbols">
<t>The test session name that MUST be identical with the
corresponding test session name on the TWAMP Control-Client (<xref
target="twamp-client"/>)</t>
<t>The control connection name, which along with the test session
name uniquely identify the TWAMP Session-Sender instance</t>
<t>Information pertaining to the test packet stream, such as, for
example, the number of test packets and the packet distribution to
be employed.</t>
</list></t>
</section>
<section anchor="twampReflector" title="Session-Reflector">
<t>Each TWAMP Session-Reflector is associated with zero or more test
sessions. For each test session, the REFWAIT parameter (Section 4.2 of <xref
target="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 <xref
target="twamp-server"/>.</t>
</section>
</section>
<section anchor="parameters" title="Data Model Parameters">
<t>This section defines the TWAMP data model using UML and describes all
associated parameters.</t>
<section anchor="clientConfig" title="Control-Client">
<t>The twamp-client container (see <xref target="fig:twamp-client"/>)
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).</t>
<figure anchor="fig:twamp-client"
title="TWAMP Control-Client UML class diagram">
<artwork><![CDATA[
+--------------------+
| 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} |
+-------------+ +-------------------------+
]]></artwork>
</figure>
<t>The twamp-client container includes an administrative parameter
(client-admin-state) that controls whether the device is allowed to
initiate TWAMP control and test sessions.</t>
<t>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 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 <xref target="RFC5618"/>, <xref target="RFC5938"/>,
and <xref target="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.</t>
<t>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 <xref target="fig:twamp-client"/>, 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 <xref target="RFC6020"/>. The derived key length (dkLen in
<xref target="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 <xref target="RFC4656"/>).</t>
<t>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.</t>
<t>The configuration items for twamp-client-ctrl-connection are: <list
hangIndent="8" style="hanging">
<t hangText="ctrl-connection-name"><vspace/>A unique name used as a
key to identify this individual TWAMP control connection on the
Control-Client device.</t>
<t hangText="client-ip"><vspace/>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.</t>
<t hangText="server-ip"><vspace/>The IP address belonging to the
remote Server device, which the TWAMP-Control connection will be
initiated to. This item is mandatory.</t>
<t hangText="server-tcp-port"><vspace/>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 <xref target="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.</t>
<t hangText="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.</t>
<t hangText="key-id"><vspace/>The key-id value that is selected for
this TWAMP-Control connection.</t>
<t hangText="max-count"><vspace/>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.</t>
</list></t>
<t>The following twamp-client-ctrl-connection parameters are read-only:
<list hangIndent="8" style="hanging">
<t hangText="client-tcp-port"><vspace/>The source TCP port number used in
the TWAMP-Control packets belonging to this control
connection.</t>
<t hangText="server-start-time"><vspace/>The Start-Time advertized
by the Server in the Server-Start message (<xref
target="RFC4656"/>, Section 3.1). This is a timestamp representing
the time when the current instantiation of the Server started
operating.</t>
<t hangText="ctrl-connection-state"><vspace/>The TWAMP-Control connection
state can be either active or idle.</t>
<t hangText="selected-mode"><vspace/>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 (<xref
target="RFC4656"/>, Section 3.1).</t>
<t hangText="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 <xref
target="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 (<xref
target="serverConfig"/>) in the clear; see also the last paragraph
of Section 6 in <xref target="RFC4656"/>.</t>
<t hangText="client-iv"><vspace/>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.</t>
</list></t>
<t>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 <xref target="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).</t>
<t>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.</t>
<t>The configuration items for twamp-session-request are: <list
hangIndent="8" style="hanging">
<t hangText="test-session-name"><vspace/>A unique name for this test
session to be used for identification of this TWAMP-Test session on the
Control-Client.</t>
<t hangText="sender-ip"><vspace/>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. 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.</t>
<t hangText="sender-udp-port"><vspace/>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 <xref target="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 is true, the device is free to
auto-allocate a different UDP port number when it negotiates the next
(repeated) iteration of this session.</t>
<t hangText="reflector-ip"><vspace/>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.</t>
<t hangText="reflector-udp-port"><vspace/>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.</t>
<t hangText="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 (<xref target="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.</t>
<t hangText="padding-length"><vspace/>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 (<xref
target="RFC4656"/>, Section 3.5).</t>
<t hangText="dscp">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. This value will be placed
in the Type-P Descriptor field of the Request-TW-Session message
(<xref target="RFC5357"/>).</t>
<t hangText="start-time"><vspace/>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.</t>
<t hangText="repeat and repeat-interval"><vspace/> 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 False, indicating
that once the session has completed, it will not be renegotiated
and restarted.</t>
<t hangText="pm-reg-list"><vspace/> A list of one or more Performance Metric Registry Index values (see <xref target="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.</t>
<t hangText="pm-index"><vspace/> One or more Numerical index values of a
Registered Metric in the Performance Metric Registry <xref
target="I-D.ietf-ippm-metric-registry"/> comprise the pm-reg-list.
Output statistics are specified in the corresponding Registry entry.</t>
</list></t>
<t>The following twamp-session-request parameters are read-only: <list
hangIndent="8" style="hanging">
<t hangText="test-session-state"><vspace/>The TWAMP-Test session state can
be either accepted or indicate the respective error code.</t>
<t hangText="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 <xref
target="RFC6038"/>.</t>
</list></t>
</section>
<section anchor="serverConfig" title="Server">
<t>The twamp-server container (see <xref target="fig:twamp-server"/>)
holds items that are related to the configuration of the TWAMP Server
logical entity (recall <xref target="fig:scope"/>).</t>
<figure anchor="fig:twamp-server"
title="TWAMP Server UML class diagram">
<artwork><![CDATA[
+------------------ -+
| 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} |
+-----------------------------------+
]]></artwork>
</figure>
<t>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.</t>
<t>Each twamp-server container holds a list named key-chain which
relates KeyIDs with the respective secret keys. As mentioned in <xref
target="clientConfig"/>, 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.</t>
<t>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.</t>
<t>The twamp-server container items are as follows: <list
hangIndent="8" style="hanging">
<t hangText="server-admin-state"><vspace/>This administrative
parameter controls whether the device is allowed to operate as a
TWAMP Server. As defined in <xref target="RFC5357"/> the roles of
Server and Session-Reflector can be played by the same host;
recall <xref target="fig:scope2"/>. For a host operating in this
manner, this parameter controls whether the device is allowed to
respond to TWAMP control and test sessions.</t>
<t hangText="server-tcp-port"><vspace/>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 <xref
target="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.</t>
<t hangText="servwait"><vspace/>TWAMP-Control (TCP) session
timeout, in seconds ((<xref target="RFC5357"/>, Section 3.1)).</t>
<t hangText="dscp">The DSCP value to be placed in the IP header of
TWAMP-Control (TCP) packets generated by the Server. Section 3.1 of
<xref target="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 implement the
behavior described in <xref target="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 <xref target="RFC5357"/>.</t>
<t hangText="count">Parameter used in deriving a key from a shared
secret as described in Section 3.1 of <xref target="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.</t>
<t hangText="max-count"><vspace/>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.</t>
<t hangText="modes"><vspace/>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.</t>
</list></t>
<t>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.</t>
<t>The twamp-server-ctrl-connection container items are all read-only:
<list hangIndent="8" style="hanging">
<t hangText="client-ip"><vspace/>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.</t>
<t hangText="client-tcp-port"><vspace/>The source TCP port number used in
the TWAMP-Control (TCP) packets belonging to this control
connection.</t>
<t hangText="server-ip"><vspace/>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.</t>
<t hangText="server-tcp-port"><vspace/>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.</t>
<t hangText="server-ctrl-connection-state"><vspace/>The Server
TWAMP-Control connection state can be active or SERVWAIT.</t>
<t hangText="dscp"><vspace/>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.</t>
<t hangText="selected-mode"><vspace/>The Mode that was chosen for
this TWAMP-Control connection as set in the Mode field of the
Set-Up-Response message.</t>
<t hangText="key-id"><vspace/>The KeyID value that is in use by
this TWAMP-Control connection. The Control-Client selects the key-id for
the control connection.</t>
<t hangText="count"><vspace/>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.</t>
<t hangText="max-count"><vspace/>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.</t>
</list><list hangIndent="8" style="hanging">
<t hangText="salt">A parameter used in deriving a key from a
shared secret as described in Section 3.1 of <xref
target="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.</t>
<t hangText="server-iv"><vspace/>The Server Initialization Vector
(IV) is generated randomly by the Server.</t>
<t hangText="challenge"><vspace/>A random sequence of
octets generated by the Server. As described in <xref
target="clientConfig"/> challenge is used by the Control-Client to
prove possession of a shared secret.</t>
</list></t>
</section>
<section anchor="senderConfig" title="Session-Sender">
<t>The twamp-session-sender container, illustrated in <xref
target="fig:twampSenders"/>, holds items that are related to the
configuration of the TWAMP Session-Sender logical entity.</t>
<t>There are no global configuration items that apply to the
Session-Sender entity as a whole.</t>
<t>There is one instance of twamp-sender-test-session for each TWAMP-Test
session for which packets are being sent.</t>
<figure anchor="fig:twampSenders"
title="TWAMP Session-Sender UML class diagram">
<artwork><![CDATA[
+----------------------+
| twamp-session-sender |
+----------------------+ 0..* +---------------------------+
| |<>-----| 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 |
+------------------------+
]]></artwork>
</figure>
<t>The twamp-sender-test-session container items are: <list
hangIndent="8" style="hanging">
<t hangText="test-session-name"><vspace/>A unique name for this TWAMP-Test
session to be used for identifying this test session by the
Session-Sender logical entity.</t>
<t hangText="ctrl-connection-name"><vspace/>The name of the parent
TWAMP-Control connection that is responsible for negotiating this TWAMP-Test
session.</t>
<t hangText="fill-mode"><vspace/>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 <xref target="RFC5357"/>.</t>
<t hangText="number-of-packets"><vspace/>The overall number of TWAMP-Test (UDP) packets to be transmitted by the Session-Sender for this test
session.</t>
<t hangText="packet-distribution"><vspace/>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.</t>
<t hangText="periodic-interval and periodic-interval-units"><vspace/>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 <xref target="RFC3432"/>.</t>
<t hangText="lambda and lambda-units"><vspace/>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 <xref target="RFC3432"/>.</t>
<t hangText="max-interval"><vspace/>If packet-distribution is
Poisson, then this parameter keeps a stream active by setting a
maximum time between packet transmissions.</t>
<t hangText="truncation-point-units"><vspace/>One of seconds,
milliseconds, microseconds, nanoseconds.</t>
</list></t>
<t>The following twamp-sender-test-session parameters are read-only:
<list hangIndent="8" style="hanging">
<t hangText="sender-session-state"><vspace/>This read-only item can
be either Active or Idle.</t>
<t hangText="sent-packets"><vspace/>The number of TWAMP-Test (UDP) packets
belonging to this session that have been transmitted by the
Session-Sender.</t>
<t hangText="rcv-packets"><vspace/>The number of TWAMP-Test (UDP) 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 sent-packets - rcv-packets.</t>
<t hangText="last-sent-seq"><vspace/>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.</t>
<t hangText="last-rcv-seq"><vspace/>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.</t>
</list></t>
</section>
<section anchor="reflectorConfig" title="Session-Reflector">
<t>The twamp-session-reflector container, illustrated in <xref
target="fig:twampReflector"/>, holds items that are related to the
configuration of the TWAMP Session-Reflector logical entity.</t>
<t>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.</t>
<t>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.</t>
<figure anchor="fig:twampReflector"
title="TWAMP Session-Reflector UML class diagram">
<artwork><![CDATA[
+-------------------------+
| twamp-session-reflector |
+-------------------------+
| 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} |
+----------------------------------------+
]]></artwork>
</figure>
<t>The twamp-session-reflector configuration items are: <list
hangIndent="8" style="hanging">
<t hangText="refwait"><vspace/>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.</t>
</list></t>
<t>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 <xref
target="RFC6038"/>.</t>
<t>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 <xref target="fig:twamp-client"/>). 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.</t>
<t>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.</t>
<t>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.</t>
<t>All data under twamp-reflector-test-session is read-only: <list
hangIndent="8" style="hanging">
<t hangText="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.</t>
<t hangText="sender-ip"><vspace/>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.</t>
<t hangText="sender-udp-port"><vspace/>The source UDP port used in
the TWAMP-Test packets belonging to this test session.</t>
<t hangText="reflector-ip"><vspace/>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.</t>
<t hangText="reflector-udp-port"><vspace/>The destination UDP port number
used in the TWAMP-Test (UDP) test packets belonging to this test
session.</t>
<t hangText="parent-connection-client-ip"><vspace/>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.</t>
<t hangText="parent-connection-client-tcp-port"><vspace/>The source
TCP port number used in the TWAMP TCP control packets belonging to the
parent control connection that negotiated this test session.</t>
<t hangText="parent-connection-server-ip"><vspace/>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.</t>
<t hangText="parent-connection-server-tcp-port"><vspace/>The
destination TCP port number used in the TWAMP-Control (TCP) packets
belonging to the parent control connection that negotiated this
test session.</t>
<t hangText="dscp">The DSCP value present in the IP header of
TWAMP-Test (UDP) packets belonging to this test session.</t>
<t hangText="sent-packets"><vspace/>The number of TWAMP-Test (UDP) response
packets that have been sent by the Session-Reflector for this test
session.</t>
<t hangText="rcv-packets"><vspace/>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.</t>
<t hangText="last-sent-seq"><vspace/>The value in the sequence
number field of the last TWAMP-Test (UDP) response packet transmitted for
this test session.</t>
<t hangText="last-rcv-seq"><vspace/>The value in the sequence number
field of the last TWAMP-Test (UDP) packet received for this test
session.</t>
</list></t>
</section>
</section>
<section anchor="module" title="Data Model">
<t>This section formally specifies the TWAMP data model using YANG.</t>
<section title="YANG Tree Diagram">
<t>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.</t>
<figure>
<artwork><![CDATA[
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? boolean
| +--rw repeat-interval? uint32
| +--rw pm-reg-list* [pm-index]
| | +--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 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
| +--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 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
]]></artwork>
</figure>
</section>
<section title="YANG Module">
<t>This section presents the YANG module for the TWAMP data model defined in this
document.</t>
<figure>
<artwork><![CDATA[
<CODE BEGINS> file "ietf-twamp@2015-06-30.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 "2015-06-30" {
description "01 version. RFC5357, RFC5618, RFC5938 and RFC6038
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 {
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.";
}
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";
}
}
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 {
type boolean;
mandatory "true";
description "Indicates whether this device is allowed to run
TWAMP to initiate control/test 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";
}
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;
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;
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 boolean;
default "false";
description "If the test session is to be run repeatedly.
The default value of repeat is False, indicating that
once the session has completed, it will not be
renegotiated and restarted";
}
leaf repeat-interval {
when "../repeat='true'" {
description "When repeat is true";
}
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/test 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.";
}
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.";
}
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.";
}
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{
if-feature session-sender;
description "Twamp session sender container";
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 {
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 refwait {
type uint32 {
range 1..604800;
}
default 900;
description "REFWAIT (TWAMP test session timeout),
the default value is 900";
}
list twamp-reflector-test-session {
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;
}
}
}
}
<CODE ENDS>
]]></artwork>
</figure>
</section>
</section>
<section anchor="examples" title="Data Model Examples">
<t>This section presents a simple but complete example of configuring
all four entities in <xref target="fig:scope"/>, based on the YANG
module specified in <xref target="module"/>. 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 <xref target="AuthExample"/>.</t>
<section anchor="ExampleCC" title="Control-Client">
<t>The following configuration example shows a Control-Client with
client-admin-state enabled. In a real implementation following <xref
target="fig:scope2"/> this would permit the initiation of TWAMP-Control connections and TWAMP-Test sessions.</t>
<figure>
<artwork><![CDATA[
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-client>
<client-admin-state>True</client-admin-state>
</twamp-client>
</twamp>
]]></artwork>
</figure>
<t>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.</t>
<figure>
<artwork><![CDATA[
<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>
]]></artwork>
</figure>
</section>
<section title="Server">
<t>This configuration example shows a Server with server-admin-state
enabled, which permits a device following <xref
target="fig:scope2"/> to respond to TWAMP-Control
connections and TWAMP-Test sessions.</t>
<figure align="left">
<preamble/>
<artwork align="left"><![CDATA[
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<twamp-server>
<server-admin-state>True</server-admin-state>
</twamp-server>
</twamp>
]]></artwork>
</figure>
<t>The following example presents a Server with the TWAMP-Control connection
corresponding to the control connection name (ctrl-connection-name)
"RouterA" presented in <xref target="ExampleCC"/>.</t>
<figure>
<artwork><![CDATA[
<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>
]]></artwork>
</figure>
</section>
<section anchor="ExampleSS" title="Session-Sender">
<t>The following configuration example shows a Session-Sender with the
two TWAMP-Test sessions presented in <xref target="ExampleCC"/>.</t>
<figure>
<artwork><![CDATA[
<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>
]]></artwork>
</figure>
</section>
<section title="Session-Reflector">
<t>The following example shows the two Session-Reflector TWAMP-Test sessions
corresponding to the test sessions presented in <xref
target="ExampleSS"/>.</t>
<figure>
<artwork><![CDATA[
<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>
<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>
]]></artwork>
</figure>
</section>
</section>
<section anchor="security" title="Security Considerations">
<t>TBD</t>
</section>
<section anchor="iana" title="IANA Considerations">
<t>This document registers a URI in the IETF XML registry <xref
target="RFC3688"/>. Following the format in <xref target="RFC3688"/>,
the following registration is requested to be made.</t>
<t>URI: urn:ietf:params:xml:ns:yang:ietf-twamp</t>
<t>Registrant Contact: The IPPM WG of the IETF.</t>
<t>XML: N/A, the requested URI is an XML namespace.</t>
<t>This document registers a YANG module in the YANG Module Names
registry <xref target="RFC6020"/>.</t>
<t>name: ietf-twamp</t>
<t>namespace: urn:ietf:params:xml:ns:yang:ietf-twamp</t>
<t>prefix: twamp</t>
<t>reference: RFC XXXX</t>
</section>
<section anchor="acks" title="Acknowledgements">
<t>We thank Gregory Mirsky, Kevin D'Souza, and Robert Sherman for their thorough and
constructive reviews, comments and text suggestions.</t>
<t>Haoxing Shen contributed to the definition of the YANG module in
<xref target="module"/>.</t>
<t>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.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include='reference.RFC.2119'?>
<?rfc include='reference.RFC.3432'?>
<?rfc include='reference.RFC.3688'?>
<?rfc include='reference.RFC.4656'?>
<?rfc include='reference.RFC.5357'?>
<?rfc include='reference.RFC.6020'?>
<?rfc include='reference.RFC.6038'?>
</references>
<references title="Informative References">
<!--<?rfc include="reference.RFC.7398"?>-->
<?rfc include='reference.RFC.2898'?>
<?rfc include='reference.RFC.4086'?>
<?rfc include='reference.RFC.5618'?>
<?rfc include='reference.RFC.5938'?>
<?rfc ?>
<?rfc include='reference.RFC.6241'?>
<?rfc include='reference.RFC.7426'?>
<?rfc include='reference.I-D.ietf-netconf-restconf'?>
<?rfc include='reference.I-D.ietf-ippm-metric-registry'?>
<?rfc include='reference.I-D.unify-nfvrg-challenges'?>
<?rfc include='reference.I-D.unify-nfvrg-devops'?>
<reference anchor="NSC">
<front>
<title>Research directions in network service chaining</title>
<author>
<organization>John, W., Pentikousis, K., et al.</organization>
</author>
<date month="November" year="2013"/>
</front>
<seriesInfo name="Proc. SDN for Future Networks and Services (SDN4FNS), Trento, Italy"
value="IEEE"/>
</reference>
</references>
<section anchor="AuthExample" title="Detailed Data Model Examples">
<t>This appendix extends the example presented in <xref
target="examples"/> by configuring more fields such as authentication
parameters, dscp values and so on.</t>
<section title="Control-Client">
<figure>
<artwork><![CDATA[
<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>
<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>
]]></artwork>
</figure>
</section>
<section title="Server">
<figure>
<artwork><![CDATA[
<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>
]]></artwork>
</figure>
</section>
<section title="Session-Sender">
<figure>
<artwork><![CDATA[
<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>
]]></artwork>
</figure>
</section>
<section title="Session-Reflector">
<figure>
<artwork><![CDATA[
<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>
<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>
]]></artwork>
</figure>
</section>
</section>
<section anchor="OperationalCommands" title="TWAMP Operational Commands">
<t>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.</t>
<t>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.</t>
<t>However, <xref target="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.</t>
</section>
</back>
</rfc>
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