| IPPM WG | R. Civil |
| Internet-Draft | Ciena Corporation |
| Intended status: Standards Track | A. Morton |
| Expires: April 22, 2018 | AT&T Labs |
| R. Rahman | |
| M. Jethanandani | |
| Cisco Systems | |
| K. Pentikousis, Ed. | |
| Travelping | |
| October 19, 2017 |
Two-Way Active Measurement Protocol (TWAMP) Data Model
draft-ietf-ippm-twamp-yang-05
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.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 22, 2018.
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
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 proprietary mechanisms developed by the corresponding TWAMP vendor. This document addresses this gap by formally specifying the TWAMP data model using YANG.
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 standardizing 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].
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].
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 examples which conform to the YANG data model specified in this document. Appendix A elaborates these examples further.
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 left 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 Control-Client and Session-Sender, while another node acts at the same time as 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 [RFC8040].
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
The data model defined in this document is orthogonal to the specific protocol used between the Config client and Config server to communicate the TWAMP configuration parameters.
Operational actions such as how TWAMP-Test sessions are started and stopped, how performance measurement results are retrieved, or how stored results are cleared, and so on, are not addressed by the configuration model defined in this document. As noted above, such operational actions are not part of the TWAMP specification [RFC5357] and hence are out of scope of this document. See also Appendix B.
The TWAMP data model includes four categories of configuration items.
First, 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), is a typical instance of a global configuration item.
A second category includes attributes that can be configured on a per TWAMP-Control connection basis, such as the Server IP address.
A third category includes attributes related to per TWAMP-Test session attributes, for instance setting different values in the Differentiated Services Code Point (DSCP) field.
Finally, the data model includes 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.
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:
Each TWAMP-Control connection, in turn, is associated with zero or more TWAMP-Test sessions. For each test session we note the following configuration items:
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 Server is associated with zero or more TWAMP-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.
A TWAMP Session-Sender has an administrative status field set at the device level that indicates whether the node is enabled to function as such.
There is one Session-Sender instance for each TWAMP-Test session that is initiated from the sending device. Primary configuration fields include:
Each TWAMP Session-Reflector has an administrative status field set at the device level to indicate whether the node is enabled to function as such.
Each Session-Reflector is associated with zero or more TWAMP-Test sessions. For each test session, the REFWAIT timeout parameter which determines whether to discontinue the session if no packets have been received ([RFC5357], Section 4.2) 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.
This section defines the TWAMP data model using UML and introduces selected parameters associated with the four TWAMP logical entities. The complete TWAMP data model specification is provided in the YANG module presented in Section 5.2.
The client container (see Figure 3) holds items that are related to the configuration of the TWAMP Control-Client logical entity (recall Figure 1).
The client container includes an administrative configuration parameter (client/admin-state) that indicates whether the device is allowed to initiate TWAMP-Control connections.
+-------------+
| client |
+-------------+ 1..* +-----------------------+
| admin-state |<>----------------------| mode-preference-chain |
| | +-----------------------+
| | 1..* +------------+ | priority |
| |<>-----| key-chain | | mode |
+-------------+ +------------+ +-----------------------+
^ | key-id |
V | secret-key |
| +------------+
| 0..*
+------------------------+
| ctrl-connection |
+------------------------+
| name |
| client-ip |
| server-ip |
| server-tcp-port | 0..* +----------------------+
| control-packet-dscp |<>-------| test-session-request |
| key-id | +----------------------+
| max-count | | name |
| client-tcp-port {ro} | | sender-ip |
| server-start-time {ro} | | sender-udp-port |
| state {ro} | | reflector-ip |
| selected-mode {ro} | | reflector-udp-port |
| token {ro} | | timeout |
| client-iv {ro} | | padding-length |
+------------------------+ | test-packet-dscp |
| start-time |
+-------------+ 1 | repeat |
| pm-reg-list |------<>| repeat-interval |
+-------------+ | state {ro} |
| pm-index | | sid {ro} |
+-------------+ +----------------------+
Figure 3: TWAMP Control-Client UML class diagram
The client container holds a list (mode-preference-chain) which specifies the Mode values according to their preferred order of use by the operator of this Control-Client, including the authentication and encryption Modes. Specifically, mode-preference-chain lists the mode and its corresponding priority, expressed as a 16-bit unsigned integer, where zero is the highest priority and subsequent values are monotonically increasing.
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], [RFC6038], and [RFC7717]. 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 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 16 octets for the AES Session-key used for encryption and 32 octets for the HMAC-SHA1 Session-key used for authentication; see also Section 6.10 of [RFC4656].
Each client container also holds a list of control connections, where each item in the list describes a TWAMP control connection initiated by this Control-Client. There SHALL be one ctrl-connection per TWAMP-Control (TCP) connection that is to be initiated from this device.
In turn, each ctrl-connection holds a list of test-session-request. test-session-request holds information associated with the Control-Client for this test session. This includes information associated with the Request-TW-Session/Accept-Session message exchange (see Section 3.5 of [RFC5357]).
There SHALL be one instance of test-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 Control-Client is also responsible for scheduling TWAMP-Test sessions so test-session-request holds information related to these actions (e.g. pm-index, repeat-interval).
The server container (see Figure 4) holds items that are related to the configuration of the TWAMP Server logical entity (recall Figure 1).
The server container includes an administrative configuration parameter (server/admin-state) that indicates whether the device is allowed to receive TWAMP-Control connections.
A device operating in the Server role cannot configure attributes on a per TWAMP-Control connection basis, as it has no foreknowledge of the incoming TWAMP-Control connections to be received. Consequently, any parameter that the Server might want to apply to an incoming control connection must be configured at the overall Server level and applied to all incoming TWAMP-Control connections.
+---------------------+
| server |
+---------------------+
| admin-state | 1..* +------------+
| server-tcp-port |<>------| key-chain |
| servwait | +------------+
| control-packet-dscp | | key-id |
| count | | secret-key |
| max-count | +------------+
| modes |
| | 0..* +--------------------------+
| |<>------| ctrl-connection |
+---------------------+ +--------------------------+
| client-ip {ro} |
| client-tcp-port {ro} |
| server-ip {ro} |
| server-tcp-port {ro} |
| state {ro} |
| control-packet-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
Each 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 active on the Server is represented by a ctrl-connection. There SHALL be one ctrl-connection per incoming TWAMP-Control (TCP) connection that is received and active on the Server. Each ctrl-connection can be uniquely identified by the 4-tuple {client-ip, client-tcp-port, server-ip, server-tcp-port}. All items in the ctrl-connection list are read-only.
The session-sender container, illustrated in Figure 5, holds items that are related to the configuration of the TWAMP Session-Sender logical entity.
The session-sender container includes an administrative parameter (session-sender/admin-state) that controls whether the device is allowed to initiate TWAMP-Test sessions.
+----------------+
| session-sender |
+----------------+ 0..* +---------------------------+
| admin-state |<>-----| test-session |
+----------------+ +---------------------------+
| name |
| ctrl-connection-name {ro} |
| fill-mode |
| number-of-packets |
| state {ro} |
| sent-packets {ro} |
| rcv-packets {ro} |
| last-sent-seq {ro} |
| last-rcv-seq {ro} |
+---------------------------+
^
V
| 1
+---------------------+
| packet-distribution |
+---------------------+
| periodic / poisson |
+---------------------+
| |
+-------------------+ |
| periodic-interval | |
+-------------------+ |
|
+--------------+
| lambda |
| max-interval |
+--------------+
Figure 5: TWAMP Session-Sender UML class diagram
Each TWAMP-Test session initiated by the Session-Sender will be represented by an instance of a test-session object. There SHALL be one instance of test-session for each TWAMP-Test session for which packets are being sent.
The session-reflector container, illustrated in Figure 6, holds items that are related to the configuration of the TWAMP Session-Reflector logical entity.
The session-reflector container includes an administrative parameter (session-reflector/admin-state) that controls whether the device is allowed to respond to incoming TWAMP-Test sessions.
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 are applied to all incoming sessions.
+----=--------------+
| session-reflector |
+-------------------+
| admin-state |
| refwait |
+-------------------+
^
V
|
| 0..*
+----------------------------------------+
| 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} |
| test-packet-dscp {ro} |
| sent-packets {ro} |
| rcv-packets {ro} |
| last-sent-seq {ro} |
| last-rcv-seq {ro} |
+----------------------------------------+
Figure 6: TWAMP Session-Reflector UML class diagram
Each incoming TWAMP-Test session that is active on the Session-Reflector SHALL be represented by an instance of a test-session object. All items in the test-session object are read-only.
Instances of test-session are indexed by a session identifier (sid). This value is auto-allocated by the TWAMP Server as test session requests are received, and communicated back to the Control-Client in the SID field of the Accept-Session message; see Section 4.3 of [RFC6038].
When attempting to retrieve operational data for active test sessions from a Session-Reflector device, the user will not know what sessions are currently active on that device, or what SIDs have been auto-allocated for these test sessions. If the user has network access to the Control-Client device, then it is possible to read the data for this session under client/ctrl-connection/test-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 session-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 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 MUST correspond to the equivalent 4-tuple {client-ip, client-tcp-port, server-ip, server-tcp-port} in server/ctrl-connection. 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.
This section formally specifies the TWAMP data model using YANG.
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 client! {control-client}?
| +--rw admin-state boolean
| +--rw mode-preference-chain* [priority]
| | +--rw priority uint16
| | +--rw mode? twamp-modes
| +--rw key-chain* [key-id]
| | +--rw key-id string
| | +--rw secret-key? binary
| +--rw ctrl-connection* [name]
| +--rw name string
| +--rw client-ip? inet:ip-address
| +--rw server-ip inet:ip-address
| +--rw server-tcp-port? inet:port-number
| +--rw control-packet-dscp? inet:dscp
| +--rw key-id? string
| +--rw max-count? uint8
| +--ro client-tcp-port? inet:port-number
| +--ro server-start-time? uint64
| +--ro repeat-count? uint64
| +--ro state? \
control-client-connection-state
| +--ro selected-mode? twamp-modes
| +--ro token? binary
| +--ro client-iv? binary
| +--rw test-session-request* [name]
| +--rw name string
| +--rw sender-ip? inet:ip-address
| +--rw sender-udp-port? union
| +--rw reflector-ip inet:ip-address
| +--rw reflector-udp-port? dynamic-port-number
| +--rw timeout? uint64
| +--rw padding-length? uint32
| +--rw test-packet-dscp? inet:dscp
| +--rw start-time? uint64
| +--rw repeat? union
| +--rw repeat-interval? uint32
| +--rw pm-reg-list* [pm-index]
| | +--rw pm-index uint16
| +--ro state? test-session-state
| +--ro sid? string
+--rw server! {server}?
| +--rw admin-state boolean
| +--rw server-tcp-port? inet:port-number
| +--rw servwait? uint32
| +--rw control-packet-dscp? inet:dscp
| +--rw count? uint8
| +--rw max-count? uint8
| +--rw modes? twamp-modes
| +--rw key-chain* [key-id]
| | +--rw key-id string
| | +--rw secret-key? binary
| +--ro 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 state? server-ctrl-connection-state
| +--ro control-packet-dscp? inet:dscp
| +--ro selected-mode? twamp-modes
| +--ro key-id? string
| +--ro count? uint8
| +--ro max-count? uint8
| +--ro salt? binary
| +--ro server-iv? binary
| +--ro challenge? binary
+--rw session-sender! {session-sender}?
| +--rw admin-state boolean
| +--rw test-session* [name]
| +--rw name string
| +--ro ctrl-connection-name? string
| +--rw fill-mode? padding-fill-mode
| +--rw number-of-packets uint32
| +--rw (packet-distribution)?
| | +--:(periodic)
| | | +--rw periodic-interval decimal64
| | +--:(poisson)
| | +--rw lambda decimal64
| | +--rw max-interval? decimal64
| +--ro state? sender-session-state
| +--ro sent-packets? uint32
| +--ro rcv-packets? uint32
| +--ro last-sent-seq? uint32
| +--ro last-rcv-seq? uint32
+--rw session-reflector! {session-reflector}?
+--rw admin-state boolean
+--rw refwait? uint32
+--ro 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 \
dynamic-port-number
+--ro reflector-ip inet:ip-address
+--ro reflector-udp-port \
dynamic-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 test-packet-dscp? inet:dscp
+--ro sent-packets? uint32
+--ro rcv-packets? uint32
+--ro last-sent-seq? uint32
+--ro last-rcv-seq? uint32
Figure 7: YANG Tree Diagram.
This section presents the YANG module for the TWAMP data model defined in this document.
<CODE BEGINS> file "ietf-twamp@2017-10-16.yang"
module ietf-twamp {
namespace
urn:ietf:params:xml:ns:yang:ietf-twamp;
prefix
ietf-twamp;
import ietf-inet-types {
prefix inet;
}
organization
"IETF IPPM (IP Performance Metrics) Working Group";
contact
draft-ietf-ippm-twamp-yang@tools.ietf.org;
description
"This YANG module specifies a vendor-independent data
model for the Two-Way Active Measurement Protocol (TWAMP).
The data model covers four TWAMP logical entities, namely,
Control-Client, Server, Session-Sender, and Session-Reflector,
as illustrated in the annotated TWAMP logical model (Fig. 1
of draft-ietf-ippm-twamp-yang).
This YANG module uses features to indicate which of the four
logical entities are supported by a TWAMP implementation.";
revision 2017-10-16 {
description
"Revision appearing in draft-ietf-ippm-twamp-yang-05.
Covers RFC 5357, RFC 5618, RFC 5938, RFC 6038, RFC 7717, and
draft-ietf-ippm-metric-registry";
reference
draft-ietf-ippm-twamp-yang;
}
/*
* Typedefs
*/
typedef twamp-modes {
type bits {
bit unauthenticated {
position 0;
description
"Unauthenticated mode, in which no encryption or
authentication is applied in TWAMP-Control and TWAMP-Test.
KeyID, Token, and Client-IV are not used in the
Set-Up-Response message. See Section 3.1 of RFC 4656.";
reference
"RFC 4656: A One-way Active Measurement Protocol (OWAMP)";
}
bit authenticated {
position 1;
description
"Authenticated mode, in which the Control-Client and Server
possess a shared secret thus prohibiting 'theft of service'.
As per Section 6 of RFC 4656, in 'authenticated mode, the
timestamp is in the clear and is not protected
cryptographically in any way, while the rest of the message
has the same protection as in encrypted mode. This mode
allows one to trade off cryptographic protection against
accuracy of timestamps.'";
reference
"RFC 4656: A One-way Active Measurement Protocol (OWAMP)";
}
bit encrypted {
position 2;
description
"Encrypted mode 'makes it impossible to alter
timestamps undetectably.' See also Section 4 of RFC 7717
and Section 6 of RFC 4656.";
reference
"RFC 4656: A One-way Active Measurement Protocol (OWAMP)";
}
bit unauth-test-encrpyt-control {
position 3;
description
"When using the Mixed Security Mode, the TWAMP-Test
protocol follows the Unauthenticated mode and the
TWAMP-Control protocol the Encrypted mode.";
reference
"RFC 5618: Mixed Security Mode for the Two-Way Active
Measurement Protocol (TWAMP)";
}
bit individual-session-control {
position 4;
description
"This mode enables individual test sessions using
Session Identifiers.";
reference
"RFC 5938: Individual Session Control Feature
for the Two-Way Active Measurement Protocol (TWAMP)";
}
bit reflect-octets {
position 5;
description
"This mode indicates the reflect octets capability.";
reference
"RFC 6038: Two-Way Active Measurement Protocol (TWAMP)
Reflect Octets and Symmetrical Size Features";
}
bit symmetrical-size {
position 6;
description
"This mode indicates support for the symmetrical size
sender test packet format.";
reference
"RFC 6038: Two-Way Active Measurement Protocol (TWAMP)
Reflect Octets and Symmetrical Size Features";
}
bit IKEv2Derived {
position 7;
description
"In this mode the the shared key is derived
from an IKEv2 security association (SA).";
reference
"RFC 7717: IKEv2-Derived Shared Secret Key for
the One-Way Active Measurement Protocol (OWAMP)
and Two-Way Active Measurement Protocol (TWAMP)";
}
}
description
"Specifies the configurable TWAMP-Modes supported during a
TWAMP-Control Connection setup between a Control-Client
and a Server. Section 7 of RFC 7717 summarizes the
TWAMP-Modes registry and points to their formal
specification.";
}
typedef control-client-connection-state {
type enumeration {
enum active {
description
"Indicates an active TWAMP-Control connection to Server.";
}
enum idle {
description
"Indicates an idle TWAMP-Control connection to Server.";
}
}
description
"Indicates the Control-Client TWAMP-Control connection state.";
}
typedef test-session-state {
type enumeration {
enum accepted {
value 0;
description
"Indicates that accepted TWAMP-Test session request.";
}
enum failed {
value 1;
description
"Indicates a TWAMP-Test session failure due to
some unspecified reason (catch-all).";
}
enum internal-error {
value 2;
description
"Indicates a TWAMP-Test session failure due to
an internal error.";
}
enum not-supported {
value 3;
description
"Indicates a TWAMP-Test session failure because
some aspect of the TWAMP-Test session request
is not supported.";
}
enum permanent-resource-limit {
value 4;
description
"Indicates a TWAMP-Test session failure due to
permanent resource limitations.";
}
enum temp-resource-limit {
value 5;
description
"Indicates a TWAMP-Test session failure due to
temporary resource limitations.";
}
}
description
"Indicates the Control-Client TWAMP-Test session state.";
}
typedef server-ctrl-connection-state {
type enumeration {
enum active {
description
"Indicates an active TWAMP-Control connection
to the Control-Client.";
}
enum servwait {
description
"Indicates that the TWAMP-Control connection to the
Control-Client is in SERVWAIT as per the definition of
Section 3.1 of RFC 5357.";
}
}
description
"Indicates the Server TWAMP-Control connection state.";
}
typedef sender-session-state {
type enumeration {
enum active {
description
"Indicates that the TWAMP-Test session is active.";
}
enum failure {
description
"Indicates that the TWAMP-Test session has failed.";
}
}
description
"Indicates the Session-Sender TWAMP-Test session state.";
}
typedef padding-fill-mode {
type enumeration {
enum zero {
description
"TWAMP-Test packets are padded with all zeros.";
}
enum random {
description
"TWAMP-Test packets are padded with pseudo-random
numbers.";
}
}
description
"Indicates what type of packet padding is used in the
TWAMP-Test packets.";
}
typedef dynamic-port-number {
type inet:port-number {
range 49152..65535;
}
description "Dynamic range for port numbers.";
}
/*
* Features
*/
feature control-client {
description
"Indicates that the device supports configuration of the
TWAMP Control-Client logical entity.";
}
feature server {
description
"Indicates that the device supports configuration of the
TWAMP Server logical entity.";
}
feature session-sender {
description
"Indicates that the device supports configuration of the
TWAMP Session-Sender logical entity.";
}
feature session-reflector {
description
"Indicates that the device supports configuration of the
TWAMP Session-Reflector logical entity.";
}
/*
* Reusable node groups
*/
grouping key-management {
list key-chain {
key key-id;
leaf key-id {
type string {
length 1..80;
}
description
"KeyID used for a TWAMP-Control connection. As per
Section 3.1 of RFC 4656, KeyID is 'a UTF-8 string, up to
80 octets in length' and is used to select which 'shared
shared secret the [Control-Client] wishes to use to
authenticate or encrypt'.";
}
leaf secret-key {
type binary;
description
"The secret key corresponding to the KeyID for this
TWAMP-Control connection.";
}
description
"Relates KeyIDs with their respective secret keys
in a TWAMP-Control connection.";
}
description
"Used by the Control-Client and Server for TWAMP-Control
key management.";
}
grouping maintenance-statistics {
leaf sent-packets {
type uint32;
config false;
description "Indicates the number of packets sent.";
}
leaf rcv-packets {
type uint32;
config false;
description "Indicates the number of packets received.";
}
leaf last-sent-seq {
type uint32;
config false;
description "Indicates the last sent sequence number.";
}
leaf last-rcv-seq {
type uint32;
config false;
description "Indicates the last received sequence number.";
}
description "Used for TWAMP-Test maintenance statistics.";
}
grouping count {
leaf count {
type uint8 {
range "10..31";
}
default 10;
description
"Parameter communicated to the Control-Client as part of the
Server Greeting message and used for deriving a key from a
shared secret as per Section 3.1 of RFC 4656: MUST be a
power of 2 and at least 1024. It is configured by providing
said power. For example, configuring 15 here means count
2^15 = 32768. The default is 10, meaning 2^10 = 1024.";
}
description
"Reusable data structure for count which is used both in the
Server container.";
}
grouping max-count {
leaf max-count {
type uint8 {
range "10..31";
}
default 15;
description
"This parameter limits the maximum Count value, which MUST
be a power of 2 and at least 1024 as per RFC 5357. It is
configured by providing said power. For example,
configuring 10 here means max count 2^10 = 1024.
The default is 15, meaning 2^15 = 32768.
A TWAMP Server uses this configured value in the
Server-Greeting message sent to the Control-Client.
A TWAMP Control-Client uses this configured value to prevent
denial-of-service (DOS) attacks by closing the control
connection to the Server if it 'receives a Server-Greeting
message with Count greater that its maximum configured value',
as per Section 6 of RFC 5357.
Further, note that according to Section 6 of RFC 5357:
'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.
TWAMP-compliant systems SHOULD have a configuration
control to limit the maximum count value. The default
max-count value SHOULD be 32768.'
RFC 5357 does not qualify 'significant period' in terms of
time, but it is clear that this depends on the processing
capacity available and operators need to pay attention to
this security consideration.";
}
description
"Reusable data structure for max-count which is used both at
the Control-Client and the Server containers.";
}
/*
* Configuration data nodes
*/
container twamp {
description
"TWAMP logical entity configuration grouping of four models
which correspond to the four TWAMP logical entities
Control-Client, Server, Session-Sender, and Session-Reflector
as illustrated in Fig. 1 of draft-ietf-ippm-twamp-yang.";
container client {
if-feature control-client;
presence "Enables TWAMP Control-Client functionality.";
description
"Configuration of the TWAMP Control-Client logical entity.";
leaf admin-state {
type boolean;
mandatory true;
description
"Indicates whether the device is allowed to operate as a
TWAMP Control-Client.";
}
list mode-preference-chain {
key priority;
unique mode;
leaf priority {
type uint16;
description
"Indicates the Control-Client Mode preference priority
expressed as a 16-bit unsigned integer, where zero is the
highest priority and subsequent values monotonically
increasing.";
}
leaf mode {
type twamp-modes;
description
"The supported TWAMP Mode matching the corresponding
priority.";
}
description
"Indicates the Control-Client preferred order of use of
the supported TWAMP Modes.
Depending on the Modes available in the TWAMP Server
Greeting message (see Fig. 2 of RFC 7717), the
this Control-Client MUST choose the highest priority Mode
from the configured mode-preference-chain list.";
}
uses key-management;
list ctrl-connection {
key name;
description
"List of TWAMP Control-Client control connections.
Each item in the list describes a control connection
that will be initiated by this Control-Client";
leaf 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
"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.";
}
leaf server-ip {
type inet:ip-address;
mandatory true;
description
"The IP address of the remote Server device, which the
TWAMP-Control connection will be initiated to.";
}
leaf server-tcp-port {
type inet:port-number;
default 862;
description
"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-Control
port number (862) as per RFC 5357 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.";
}
leaf control-packet-dscp {
type inet:dscp;
default 0;
description
"The DSCP value to be placed in the IP header of
TWAMP-Control (TCP) packets generated by this
Control-Client.";
}
leaf key-id {
type string {
length 1..80;
}
description
"Indicates the KeyID value selected for this
TWAMP-Control connection.";
}
uses max-count;
leaf client-tcp-port {
type inet:port-number;
config false;
description
"Indicates the source TCP port number used in the
TWAMP-Control packets belonging to this control
connection.";
}
leaf server-start-time {
type uint64;
config false;
description
"Indicates the Start-Time advertized by the Server in the
Server-Start message (RFC 4656, Section 3.1),
representing the time when the current
instantiation of the Server started operating.
The timestamp format follows RFC 1305
according to Section 4.1.2 of RFC 4656.";
}
leaf state {
type control-client-connection-state;
config false;
description
"Indicates the current state of the TWAMP-Control
connection state.";
}
leaf selected-mode {
type twamp-modes;
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 (RFC 4656, Section 3.1).";
}
leaf token {
type binary {
length 64;
}
config false;
description
"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; see also
the last paragraph of Section 6 in RFC 4656.
If the Mode defined in RFC 7717 is selected (selected-mode),
Token is limited to 16 octets.";
reference
"RFC 4086: Randomness Requirements for Security
RFC 7717: IKEv2-Derived Shared Secret Key for the One-Way
Active Measurement Protocol (OWAMP) and Two-Way Active
Measurement Protocol (TWAMP)";
}
leaf client-iv {
type binary {
length 16;
}
config false;
description
"Indicates the Control-Client Initialization Vector
(Client-IV), that is generated randomly by the
Control-Client. As per RFC 4656:
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.
If the Mode defined in RFC 7717 is selected (selected-mode),
Client-IV is limited to 12 octets.";
reference
"RFC 4656: A One-way Active Measurement Protocol (OWAMP)
RFC 7717: IKEv2-Derived Shared Secret Key for the One-Way
Active Measurement Protocol (OWAMP) and Two-Way Active
Measurement Protocol (TWAMP)"; }
list test-session-request {
key name;
description
"Information associated with the Control-Client
for this test session";
leaf name {
type string;
description
"A unique name to be used for identification of
this TWAMP-Test session on the Control-Client.";
}
leaf sender-ip {
type inet:ip-address;
description
"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.";
}
leaf sender-udp-port {
type union {
type dynamic-port-number;
type enumeration {
enum autoallocate {
description
"Indicates that the Contol-Client will
auto-allocate the TWAMP-Test (UDP) port number
from the dynamic port range.";
}
}
}
default autoallocate;
description
"The UDP port number that is to be used by
the Session-Sender for this TWAMP-Test session.
The number is restricted to the dynamic port range.
By default 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 Section 3.5 of RFC 5357). 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.";
}
leaf reflector-ip {
type inet:ip-address;
mandatory true;
description
"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.";
}
leaf reflector-udp-port {
type dynamic-port-number;
description
"This parameter defines the UDP port number that
will be used by the Session-Reflector for
this TWAMP-Test session. The number is restricted
to the dynamic port range and is to be placed in
the Receiver Port field of the Request-TW-Session
message.";
}
leaf timeout {
type uint64;
units seconds;
default 2;
description
"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 (RFC 5357, Section 3.8).
This value will be placed in the Timeout field of
the Request-TW-Session message.";
}
leaf padding-length {
type uint32 {
range 64..4096;
}
description
"The number of padding bytes to 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
(RFC 4656, Section 3.5).";
}
leaf test-packet-dscp {
type inet:dscp;
default 0;
description
"The DSCP value to be placed in the IP 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 (RFC 5357).";
}
leaf start-time {
type uint64;
default 0;
description
"Time when the session is to be started
(but not before the TWAMP Start-Sessions command
is issued; see Section 3.4 of RFC 5357).
The start-time value is placed in the Start Time
field of the Request-TW-Session message.
The timestamp format follows RFC 1305 as per
Section 3.5 of RFC 4656.
The default value of 0 indicates that the session
will be started as soon as the Start-Sessions message
is received.";
}
leaf repeat {
type union {
type uint32 {
range 0..4294967294;
}
type enumeration {
enum forever {
description
"Indicates that the test session SHALL be
repeated *forever* using the information in
repeat-interval parameter, and SHALL NOT
decrement the value.";
}
}
}
default 0;
description
"This value determines if the TWAMP-Test session must
be repeated. When a test session has completed, the
repeat parameter is checked.
The default value of 0 indicates that the session
MUST NOT be repeated.
If the repeat value is 1 through 4,294,967,294
then the test session SHALL be repeated using the
information in repeat-interval parameter, and the
parent TWAMP-Control connection for this test
session is restarted to negotiate a new instance
of this TWAMP-Test session. The implementation
MUST decrement the value of repeat after
determining a repeated session is expected.";
}
leaf repeat-interval {
when "../repeat!='0'" {
description
"This parameter determines the timing of repeated
TWAMP-Test sessions when repeat is more than 0.
When the value of repeat-interval is 0, the
negotiation of a new test session SHALL begin
immediately after the previous test session
completes. Otherwise, the Control-Client will
wait for the number of seconds specified in the
repeat-interval parameter before negotiating the
new instance of this TWAMP-Test session.";
}
type uint32;
units seconds;
default 0;
description "Repeat interval (in seconds).";
}
list pm-reg-list {
key pm-index;
leaf pm-index {
type uint16;
description
"Numerical index value of a Registered Metric
in the Performance Metric Registry
(see ietf-ippm-metric-registry). Output statistics
are specified in the corresponding Registry entry.";
}
description
"A list of one or more Performance Metric Registry
Index values, which communicate packet stream
characteristics along with 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.";
reference
"ietf-ippm-metric-registry:
Registry for Performance Metrics";
}
leaf repeat-count {
type uint64;
config false;
description
"Indicates how many times the test session has been
repeated. When a test is running, this value will be
greater than 0. If the repeat parameter is non-zero,
this value is smaller than or equal to the repeat
parameter.";
}
leaf state {
type test-session-state;
config false;
description
"Indicates the TWAMP-Test session state (accepted or
indication of an error); see Section 3.5 of
RFC 5357.";
}
leaf sid {
type string;
config false;
description
"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 RFC 6038.";
}
}
}
}
container server {
if-feature server;
presence "Enables TWAMP Server functionality.";
description "Configuration of the TWAMP Server logical entity.";
leaf admin-state {
type boolean;
mandatory true;
description
"Indicates whether the device is allowed to operate
as a TWAMP Server.";
}
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-Control. The Server will listen
on this port number for incoming TWAMP-Control
connections. Although this is defined as a fixed value
(862) in RFC 5357, 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.";
}
leaf servwait {
type uint32 {
range 1..604800;
}
units seconds;
default 900;
description
"TWAMP-Control (TCP) session timeout, in seconds.
According to Section 3.1 of RFC 5357,
Server MAY discontinue any established control
connection when no packet associated with that
connection has been received within SERVWAIT seconds.";
}
leaf control-packet-dscp {
type inet:dscp;
description
"The DSCP value to be placed in the IP header of
TWAMP-Control (TCP) packets generated by the Server.
Section 3.1 of RFC 5357 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 RFC 5357 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 RFC 5357.";
}
uses count;
uses max-count;
leaf modes {
type twamp-modes;
description
"The bit mask of TWAMP Modes this Server instance
is willing to support; see IANA TWAMP Modes Registry.";
}
uses key-management;
list ctrl-connection {
key "client-ip client-tcp-port server-ip server-tcp-port";
config false;
description
"List of all incoming TWAMP-Control (TCP) connections.";
leaf client-ip {
type inet:ip-address;
description
"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.";
}
leaf client-tcp-port {
type inet:port-number;
description
"The source TCP port number used in the TWAMP-Control
(TCP) packets belonging to this control connection.";
}
leaf server-ip {
type inet:ip-address;
description
"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.";
}
leaf server-tcp-port {
type inet:port-number;
description
"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 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.";
}
leaf state {
type server-ctrl-connection-state;
description
"Indicates the Server TWAMP-Control connection state.";
}
leaf control-packet-dscp {
type inet:dscp;
description
"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
control-packet-dscp parameter under the twamp/server
container. However, in the event that the user
re-configures 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.";
}
leaf selected-mode {
type twamp-modes;
description
"The Mode that was chosen for this TWAMP-Control
connection as set in the Mode field of the
Set-Up-Response message.";
}
leaf key-id {
type string {
length 1..80;
}
description
"The KeyID value that is in use by this TWAMP-Control
connection as selected by Control-Client.";
}
uses count {
description
"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 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.";
}
uses max-count {
description
"This read-only value indicates the actual max-count in use
for this control connection. Usually this would be the
same value as configured under twamp/server.";
}
leaf salt {
type binary {
length 16;
}
description
"A parameter used in deriving a key from a
shared secret as described in Section 3.1 of RFC 4656.
It is communicated to the Control-Client as part of
the Server Greeting message.";
}
leaf server-iv {
type binary {
length 16;
}
description
"The Server Initialization Vector
(IV) generated randomly by the Server.";
}
leaf challenge {
type binary {
length 16;
}
description
"A random sequence of octets generated by the Server.
As described in client/token, Challenge is used
by the Control-Client to prove possession of a
shared secret.";
}
}
}
container session-sender {
if-feature session-sender;
presence "Enables TWAMP Session-Sender functionality.";
description
"Configuration of the TWAMP Session-Sender logical entity";
leaf admin-state {
type boolean;
mandatory true;
description
"Indicates whether the device is allowed to operate
as a TWAMP Session-Sender.";
}
list test-session{
key name;
description "List of TWAMP Session-Sender test sessions.";
leaf name {
type string;
description
"A unique name for this TWAMP-Test session to be used
for identifying this test session by the Session-Sender
logical entity.";
}
leaf ctrl-connection-name {
type string;
config false;
description
"The name of the parent TWAMP-Control connection that
is responsible for negotiating this TWAMP-Test session.";
}
leaf fill-mode {
type padding-fill-mode;
default zero;
description
"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 RFC 5357.";
}
leaf number-of-packets {
type uint32;
mandatory true;
description
"The overall number of TWAMP-Test (UDP) packets to be
transmitted by the Session-Sender for this test session.";
}
choice packet-distribution {
description
"Indicates the distribution to be used for transmitting
the TWAMP-Test (UDP) packets.";
case periodic {
leaf periodic-interval {
type decimal64 {
fraction-digits 5;
}
units seconds;
mandatory true;
description
"Indicates the time to wait (in seconds) between the
first bits of TWAMP-Test (UDP) packet transmissions for
this test session";
reference
"RFC 3432: Network performance measurement
with periodic streams";
}
}
case poisson {
leaf lambda {
type decimal64 {
fraction-digits 5;
}
units seconds;
mandatory true;
description
"Indicates the average time interval (in seconds)
between packets in the Poisson distribution.
The packet is calculated using the reciprocal of lambda
and the TWAMP-Test packet size (which depends on the
selected Mode and the packet padding).";
reference
"RFC 2330: Framework for IP Performance Metrics";
}
leaf max-interval {
type decimal64 {
fraction-digits 5;
}
units seconds;
description
"Indicates the maximum time (in seconds)
between packet transmissions.";
reference
"RFC 7312: Advanced Stream and Sampling Framework
for IP Performance Metrics (IPPM)";
}
}
}
leaf state {
type sender-session-state;
config false;
description
"Indicates the Session-Sender test session state.";
}
uses maintenance-statistics;
}
}
container session-reflector {
if-feature session-reflector;
presence "Enables TWAMP Session-Reflector functionality.";
description
"Configuration of the TWAMP Session-Reflector logical entity";
leaf admin-state {
type boolean;
mandatory true;
description
"Indicates whether the device is allowed to operate
as a TWAMP Session-Reflector.";
}
leaf refwait {
type uint32 {
range 1..604800;
}
units seconds;
default 900;
description
"The Session-Reflector MAY discontinue any session that has
been started when no packet associated with that session has
been received for REFWAIT seconds. As per Section 3.1 of
RFC 5357, this timeout allows a Session-Reflector to free up
resources in case of failure.";
}
list test-session {
key
"sender-ip sender-udp-port
reflector-ip reflector-udp-port";
config false;
description "TWAMP Session-Reflectortest sessions.";
leaf sid {
type string;
description
"An auto-allocated identifier for this TWAMP-Test
session that is unique within the context of this
Server/Session-Reflector device only. This value
is communicated to the Control-Client that
requested the test session in the SID field of the
Accept-Session message.";
}
leaf sender-ip {
type inet:ip-address;
description
"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.";
}
leaf sender-udp-port {
type dynamic-port-number;
description
"The source UDP port used in the TWAMP-Test packets
belonging to this test session.";
}
leaf reflector-ip {
type inet:ip-address;
description
"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.";
}
leaf reflector-udp-port {
type dynamic-port-number;
description
"The destination UDP port number used in the
TWAMP-Test (UDP) test packets belonging to this
test session.";
}
leaf parent-connection-client-ip {
type inet:ip-address;
description
"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.";
}
leaf parent-connection-client-tcp-port {
type inet:port-number;
description
"The source TCP port number used in the TWAMP-Control
(TCP) packets belonging to the parent control connection
that negotiated this test session.";
}
leaf parent-connection-server-ip {
type inet:ip-address;
description
"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.";
}
leaf parent-connection-server-tcp-port {
type inet:port-number;
description
"The destination TCP port number used in the TWAMP-Control
(TCP) packets belonging to the parent control connection
that negotiated this test session.";
}
leaf test-packet-dscp {
type inet:dscp;
description
"The DSCP value present in the IP header of
TWAMP-Test (UDP) packets belonging to this session.";
}
uses maintenance-statistics;
}
}
}
}
<CODE ENDS>
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. For completeness, examples are provided for both IPv4 and IPv6.
A more elaborated example, which also includes authentication parameters, is provided in Appendix A.
Figure 8 shows a configuration example for 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.
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<client>
<admin-state>true</admin-state>
</client>
</twamp>
</config>
Figure 8: XML instance enabling Control-Client operation.
The following example shows a Control-Client with two instances of 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.
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<client>
<admin-state>true</admin-state>
<ctrl-connection>
<name>RouterA</name>
<client-ip>203.0.113.1</client-ip>
<server-ip>203.0.113.2</server-ip>
<test-session-request>
<name>Test1</name>
<sender-ip>203.0.113.3</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>203.0.113.4</reflector-ip>
<reflector-udp-port>50001</reflector-udp-port>
<start-time>0</start-time>
</test-session-request>
<test-session-request>
<name>Test2</name>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>203.0.113.2</reflector-ip>
<reflector-udp-port>50001</reflector-udp-port>
<start-time>0</start-time>
</test-session-request>
</ctrl-connection>
<ctrl-connection>
<name>RouterB</name>
<client-ip>203.0.113.1</client-ip>
<server-ip>203.0.113.3</server-ip>
</ctrl-connection>
</client>
</twamp>
</config>
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<client>
<admin-state>true</admin-state>
<ctrl-connection>
<name>RouterA</name>
<client-ip>2001:DB8:203:0:113::1</client-ip>
<server-ip>2001:DB8:203:0:113::2</server-ip>
<test-session-request>
<name>Test1</name>
<sender-ip>2001:DB8:203:1:113::3</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>2001:DB8:203:1:113::4</reflector-ip>
<reflector-udp-port>55000</reflector-udp-port>
<start-time>0</start-time>
</test-session-request>
<test-session-request>
<name>Test2</name>
<sender-ip>2001:DB8:203:0:113::1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>2001:DB8:203:0:113::2</reflector-ip>
<reflector-udp-port>55001</reflector-udp-port>
<start-time>0</start-time>
</test-session-request>
</ctrl-connection>
<ctrl-connection>
<name>RouterB</name>
<client-ip>2001:DB8:203:0:113::1</client-ip>
<server-ip>2001:DB8:203:0:113::3</server-ip>
</ctrl-connection>
</client>
</twamp>
</config>
Figure 9 shows a configuration example for a Server with server/admin-state enabled, which permits a device following Figure 2 to respond to TWAMP-Control connections and TWAMP-Test sessions.
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<server>
<admin-state>true</admin-state>
</server>
</twamp>
</config>
Figure 9: XML instance enabling Server operation.
The following example presents a Server with the TWAMP-Control connection corresponding to the control connection name (client/ctrl-connection/name) "RouterA" presented in Section 6.1.
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<server>
<admin-state>true</admin-state>
<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>
<state>
active
</state>
</ctrl-connection>
</server>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<server>
<admin-state>true</admin-state>
<ctrl-connection>
<client-ip>2001:DB8:203:0:113::1</client-ip>
<client-tcp-port>16341</client-tcp-port>
<server-ip>2001:DB8:203:0:113::2</server-ip>
<server-tcp-port>862</server-tcp-port>
<state>
active
</state>
</ctrl-connection>
</server>
</twamp>
</data>
Figure 10 shows a configuration example for a Session-Sender with session-sender/admin-state enabled, which permits a device following Figure 2 to initiate TWAMP-Test sessions.
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-sender>
<admin-state>true</admin-state>
</session-sender>
</twamp>
</config>
Figure 10: XML instance enabling Session-Sender operation.
The following configuration example shows a Session-Sender with the two TWAMP-Test sessions presented in Section 6.1.
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-sender>
<admin-state>true</admin-state>
<test-session>
<name>Test1</name>
<ctrl-connection-name>RouterA</ctrl-connection-name>
<number-of-packets>900</number-of-packets>
<periodic-interval>1</periodic-interval>
<state>setup</state>
</test-session>
<test-session>
<name>Test2</name>
<ctrl-connection-name>
RouterA
</ctrl-connection-name>
<number-of-packets>900</number-of-packets>
<lambda>1</lambda>
<max-interval>2</max-interval>
<state>setup</state>
</test-session>
</session-sender>
</twamp>
</data>
This configuration example shows a Session-Reflector with session-reflector/admin-state enabled, which permits a device following Figure 2 to respond to TWAMP-Test sessions.
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-reflector>
<admin-state>true</admin-state>
</session-reflector>
</twamp>
</config>
Figure 11: XML instance enabling Session-Reflector operation.
The following example shows the two Session-Reflector TWAMP-Test sessions corresponding to the test sessions presented in Section 6.3.
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-reflector>
<admin-state>true</admin-state>
<test-session>
<sender-ip>203.0.113.3</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>203.0.113.4</reflector-ip>
<reflector-udp-port>50001</reflector-udp-port>
<sid>1232</sid>
<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>
</test-session>
<test-session>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>192.68.0.2</reflector-ip>
<reflector-udp-port>50001</reflector-udp-port>
<sid>178943</sid>
<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>21</sent-packets>
<rcv-packets>21</rcv-packets>
<last-sent-seq>20</last-sent-seq>
<last-rcv-seq>20</last-rcv-seq>
</test-session>
</session-reflector>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-reflector>
<admin-state>true</admin-state>
<test-session>
<sender-ip>203.0.113.3</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>203.0.113.4</reflector-ip>
<reflector-udp-port>54001</reflector-udp-port>
<sid>1232</sid>
<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>
</test-session>
<test-session>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>192.68.0.2</reflector-ip>
<reflector-udp-port>55001</reflector-udp-port>
<sid>178943</sid>
<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>21</sent-packets>
<rcv-packets>21</rcv-packets>
<last-sent-seq>20</last-sent-seq>
<last-rcv-seq>20</last-rcv-seq>
</test-session>
</session-reflector>
</twamp>
</data>
The YANG module defined in Section 5 is designed to be accessed, among other protocols, via NETCONF. Protocols like NETCONF use a secure transport layer like SSH that is mandatory to implement. The NETCONF Access Control Module (NACM) provides the means to restrict access for particular users to a pre-configured set of NETCONF protocol operations and attributes.
There are a number of nodes defined in this YANG module which are writeable. These data nodes may be considered sensitive and vulnerable to attacks in some network environments. Ability to write into these nodes without proper protection can have a negative effect on the devices that support this feature.
Examples of nodes that are particularly vulnerable include several timeout values put in the protocol to protect against sessions that are not active but are consuming resources.
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
We thank Fred Baker, Kevin D'Souza, Gregory Mirsky, Brian Trammell, Robert Sherman, and Marius Georgescu for their thorough and constructive reviews, comments and text suggestions.
Haoxing Shen contributed to the definition of the YANG module in Section 5.
Jan Lindblad and Ladislav Lhokta did thorough reviews of the YANG module and the examples in Appendix A.
Kostas Pentikousis was 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.
Lianshu Zheng, Huawei Technologies, China
Email: vero.zheng@huawei.com
This appendix extends the example presented in Section 6 by configuring more fields such as authentication parameters, DSCP values and so on.
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<client>
<admin-state>true</admin-state>
<mode-preference-chain>
<priority>0</priority>
<mode>authenticated</mode>
</mode-preference-chain>
<mode-preference-chain>
<priority>1</priority>
<mode>unauthenticated</mode>
</mode-preference-chain>
<key-chain>
<key-id>KeyClient1ToRouterA</key-id>
<secret-key>secret1</secret-key>
</key-chain>
<key-chain>
<key-id>KeyForRouterB</key-id>
<secret-key>secret2</secret-key>
</key-chain>
<ctrl-connection>
<name>RouterA</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>
<test-session-request>
<name>Test1</name>
<sender-ip>203.0.113.3</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>203.0.113.4</reflector-ip>
<reflector-udp-port>55000</reflector-udp-port>
<padding-length>64</padding-length>
<start-time>0</start-time>
<state>ok</state>
<sid>1232</sid>
</test-session-request>
<test-session-request>
<name>Test2</name>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>203.0.113.2</reflector-ip>
<reflector-udp-port>55001</reflector-udp-port>
<padding-length>128</padding-length>
<start-time>0</start-time>
<state>ok</state>
<sid>178943</sid>
</test-session-request>
</ctrl-connection>
</client>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<client>
<admin-state>true</admin-state>
<mode-preference-chain>
<priority>0</priority>
<mode>authenticated</mode>
</mode-preference-chain>
<mode-preference-chain>
<priority>1</priority>
<mode>unauthenticated</mode>
</mode-preference-chain>
<key-chain>
<key-id>KeyClient1ToRouterA</key-id>
<secret-key>secret1</secret-key>
</key-chain>
<key-chain>
<key-id>KeyForRouterB</key-id>
<secret-key>secret2</secret-key>
</key-chain>
<ctrl-connection>
<name>RouterA</name>
<client-ip>2001:DB8:203:0:113::1</client-ip>
<server-ip>2001:DB8:203:0:113::2</server-ip>
<dscp>32</dscp>
<key-id>KeyClient1ToRouterA</key-id>
<test-session-request>
<name>Test1</name>
<sender-ip>2001:DB8:10:1:1::1</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>2001:DB8:10:1:1::2</reflector-ip>
<reflector-udp-port>55000</reflector-udp-port>
<padding-length>64</padding-length>
<start-time>0</start-time>
<state>ok</state>
<sid>1232</sid>
</test-session-request>
<test-session-request>
<name>Test2</name>
<sender-ip>2001:DB8:203:0:113::1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>2001:DB8:203:0:113::2</reflector-ip>
<reflector-udp-port>55001</reflector-udp-port>
<padding-length>128</padding-length>
<start-time>0</start-time>
<state>ok</state>
<sid>178943</sid>
</test-session-request>
</ctrl-connection>
</client>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<server>
<admin-state>true</admin-state>
<servwait>1800</servwait>
<dscp>32</dscp>
<modes>authenticated unauthenticated</modes>
<count>1024</count>
<key-chain>
<key-id>KeyClient1ToRouterA</key-id>
<secret-key>secret1</secret-key>
</key-chain>
<key-chain>
<key-id>KeyClient10ToRouterA</key-id>
<secret-key>secret10</secret-key>
</key-chain>
<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>
<state>
active
</state>
<dscp>32</dscp>
<selected-mode>unauthenticated</selected-mode>
<key-id>KeyClient1ToRouterA</key-id>
<count>1024</count>
</ctrl-connection>
</server>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<server>
<admin-state>true</admin-state>
<servwait>1800</servwait>
<dscp>32</dscp>
<modes>authenticated unauthenticated</modes>
<count>1024</count>
<key-chain>
<key-id>KeyClient1ToRouterA</key-id>
<secret-key>secret1</secret-key>
</key-chain>
<key-chain>
<key-id>KeyClient10ToRouterA</key-id>
<secret-key>secret10</secret-key>
</key-chain>
<ctrl-connection>
<client-ip>2001:DB8:203:0:113::1</client-ip>
<client-tcp-port>16341</client-tcp-port>
<server-ip>2001:DB8:203:0:113::2</server-ip>
<server-tcp-port>862</server-tcp-port>
<state>
active
</state>
<dscp>32</dscp>
<selected-mode>unauthenticated</selected-mode>
<key-id>KeyClient1ToRouterA</key-id>
<count>1024</count>
</ctrl-connection>
</server>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-sender>
<admin-state>true</admin-state>
<test-session>
<name>Test1</name>
<ctrl-connection-name>RouterA</ctrl-connection-name>
<fill-mode>zero</fill-mode>
<number-of-packets>900</number-of-packets>
<periodic-interval>1</periodic-interval>
<state>setup</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>
</test-session>
<test-session>
<name>Test2</name>
<ctrl-connection-name>
RouterA
</ctrl-connection-name>
<fill-mode>random</fill-mode>
<number-of-packets>900</number-of-packets>
<lambda>1</lambda>
<max-interval>2</max-interval>
<state>setup</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>
</test-session>
</session-sender>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-reflector>
<admin-state>
true
</admin-state>
<test-session>
<sender-ip>203.0.113.3</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>203.0.113.4</reflector-ip>
<reflector-udp-port>55000</reflector-udp-port>
<sid>1232</sid>
<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>
</test-session>
<test-session>
<sender-ip>203.0.113.1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>192.68.0.2</reflector-ip>
<reflector-udp-port>55001</reflector-udp-port>
<sid>178943</sid>
<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>21</sent-packets>
<rcv-packets>21</rcv-packets>
<last-sent-seq>20</last-sent-seq>
<last-rcv-seq>20</last-rcv-seq>
</test-session>
</session-reflector>
</twamp>
</data>
<?xml version="1.0" encoding="utf-8"?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<twamp xmlns="urn:ietf:params:xml:ns:yang:ietf-twamp">
<session-reflector>
<admin-state>true</admin-state>
<test-session>
<sender-ip>2001:DB8:10:1:1::1</sender-ip>
<sender-udp-port>54000</sender-udp-port>
<reflector-ip>2001:DB8:10:1:1::2</reflector-ip>
<reflector-udp-port>55000</reflector-udp-port>
<sid>1232</sid>
<parent-connection-client-ip>
2001:DB8:203:0:113::1
</parent-connection-client-ip>
<parent-connection-client-tcp-port>
16341
</parent-connection-client-tcp-port>
<parent-connection-server-ip>
2001:DB8:203:0:113::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>
</test-session>
<test-session>
<sender-ip>2001:DB8:203:0:113::1</sender-ip>
<sender-udp-port>54001</sender-udp-port>
<reflector-ip>2001:DB8:192:68::2</reflector-ip>
<reflector-udp-port>55001</reflector-udp-port>
<sid>178943</sid>
<parent-connection-client-ip>
2001:DB8:203:0:113::1
</parent-connection-client-ip>
<parent-connection-client-tcp-port>
16341
</parent-connection-client-tcp-port>
<parent-connection-server-ip>
2001:DB8:203:0:113::2
</parent-connection-server-ip>
<parent-connection-server-tcp-port>
862
</parent-connection-server-tcp-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>
</test-session>
</session-reflector>
</twamp>
</data>
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, in principle, possible to define TWAMP RPC operations for actions such as starting or stopping control connections 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. Refer also to Section 2 and the unlabeled links in Figure 1. In actual deployments different TWAMP implementations may 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.