Simple Two-way Active Measurement Protocol (STAMP) Data Model

Introduction The Simple Two-way Active Measurement Protocol (STAMP) can be used to measure performance parameters of IP networks such as latency, jitter, and packet loss by sending test packets and monitoring their experience in the network. The STAMP protocol in unauthenticated mode is on-wire compatible with TWAMP Light, discussed in Appendix I . The TWAMP Light is known to have many implementations though no common management framework being defined, thus leaving some aspects of test packet processing to interpretation. As one of the goals of STAMP is to support these variations, this document presents their analysis; describes the data model of the base STAMP specification. The defined STAMP data model can be augmented to include STAMP extensions, for example, described in . This document defines the STAMP data model and specifies it formally, using the YANG data modeling language . This version of the interfaces data model conforms to the Network Management Datastore Architecture (NMDA) defined in .

Conventions used in this document

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Scope, Model, and Applicability The scope of this document includes a model of the STAMP as defined in and Section 3 .

STAMP Reference Model | STAMP Session-Reflector | +----------------------+ +-------------------------+ ]]>

Data Model Parameters This section describes containers within the STAMP data model.

STAMP-Sender The stamp-session-sender container holds items that are related to the configuration of the stamp Session-Sender logical entity. The stamp-session-sender-state container holds information about the state of the particular STAMP test session. RPCs stamp-sender-start and stamp-sender-stop respectively start and stop the referenced session by the stamp-session-id of the STAMP.

Controls for Test Session and Performance Metric Calculation The data model supports several scenarios for a STAMP Session-Sender to execute test sessions and calculate performance metrics:

The test mode in which the test packets are sent unbound in time as defined by the parameter 'interval' in the stamp-session-sender container frequency is referred to as continuous mode. Performance metrics in the continuous mode are calculated at a period defined by the parameter 'measurement-interval'.
The test mode that has a specific number of the test packets configured for the test session in the 'number-of-packets' parameter is referred to as a periodic mode. The STAMP-Sender MAY repeat the test session with the same parameters. The 'repeat' parameter defines the number of tests and the 'repeat-interval' - the interval between the consecutive tests. The performance metrics are calculated after each test session when the interval defined by the 'session-timeout' expires.

STAMP-Reflector The stamp-session-reflector container holds items that are related to the configuration of the STAMP Session-Reflector logical entity. The stamp-session-refl-state container holds Session-Reflector state data for the particular STAMP test session.

Data Model Creating the STAMP data model presents several challenges, and among them is the identification of a test-session at Session-Reflector. A Session-Reflector MAY require only as little as the STAMP Session Identifier (SSID) and the source IP address in received STAMP-Test packet to spawn a new test session. More so, to test processing of Class-of-Service along the same route in Equal Cost Multi-Path environment Session-Sender may perform STAMP test sessions concurrently using the same source IP address, source UDP port number, destination IP address, and destination UDP port number. Thus the only parameter that can be used to differentiate these test sessions would be DSCP value. The DSCP field may get re-marked along the path, and without the use of Class of Service TLV (Section 4.4 ) that will go undetected, but by using SSID and the source IP address as a key, we can ensure that STAMP test packets that are considered as different test sessions follow the same path even in ECMP environments.

Tree Diagrams This section presents a simplified graphical representation of the STAMP data model using a YANG tree diagram .

STAMP Configuration Tree Diagram

STAMP State Tree Diagram

STAMP RPC Tree Diagram

YANG Module

IANA Considerations This document registers a URI in the IETF XML registry . Following the format in , the following registration is requested to be made. URI: urn:ietf:params:xml:ns:yang:ietf-stamp 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 . name: ietf-stamp namespace: urn:ietf:params:xml:ns:yang:ietf-stamp prefix: stamp reference: RFC XXXX

Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF or RESTCONF . The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) . The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS . The NETCONF access control model provides the means to restrict access for particular NETCONF or RESTCONF users to a pre-configured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have an adverse effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability: TBD Unauthorized access to any data node of these subtrees can adversely affect the routing subsystem of both the local device and the network. This may lead to corruption of the measurement that may result in false corrective action, e.g., false negative or false positive. That could be, for example, prolonged and undetected deterioration of the quality of service or actions to improve the quality unwarranted by the real network conditions. Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability: TBD Unauthorized access to any data node of these subtrees can disclose the operational state information of VRRP on this device. Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability: TBD

Acknowledgments Authors recognize and appreciate valuable comments provided by Adrian Pan and Henrik Nydell.

References Normative References Informative References

Example of STAMP Session Configuration shows a configuration example of a STAMP-Sender.

XML instance of STAMP Session-Sender configuration

enable

forever

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XML instance of STAMP Session-Reflector configuration

enable

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