| Network Working Group | G. Mirsky |
| Internet-Draft | T. Elteto |
| Intended status: Standards Track | Ericsson |
| Expires: January 7, 2016 | July 6, 2015 |
Two-Way Active Measurement Protocol (TWAMP) Light Data Model
draft-mirsky-ippm-twamp-light-yang-00
This document specifies the data model for implementations of Session-Sender and Session-Reflector for Two-Way Active Measurement Protocol (TWAMP) Light mode using YANG.
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The Two-Way Active Measurement Protocol (TWAMP) [RFC5357] 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 [RFC5357] defines two protocols, TWAMP Control and TWAMP Test, and a profile of TWAMP Test, TWAMP Light. 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. The goal of this document is to collect analyze these variations; describe common model while allowing for extensions in the future. 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", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
The scope of this document includes model of the TWAMP Light as defined in Appendix I of [RFC5357] as well as model of accepted Errata. The former mode of TWAMP Light will be referred in this document as Stateless and the latter - Stateful. This document benefits from earlier attempt to define TWAMP MIB in [I-D.elteto-ippm-twamp-mib] and from TWAMP YANG model defined in [I-D.cmzrjp-ippm-twamp-yang].
Figure 1 updates TWAMP-Light reference model presented in Appendix I [RFC5357] for the scenario when instantiation of a TWAMP-Test session between Session-Sender and Session-Reflector controlled by communication between a Configuration Client as a manager and Configuration Servers as agents of the configuration session.
o----------------------------------------------------------o
| Config client |
o----------------------------------------------------------o
|| ||
|| NETCONF/RESTCONF ||
|| ||
o-------------------o o-------------------o
| Config server | | Config server |
| | | |
+-------------------+ +-------------------+
| Session-Sender | <--- TWAMP-Test ---> | Session-Reflector |
+-------------------+ +-------------------+
Figure 1: TWAMP Light Reference Model
TBA
TBA
Creating TWAMP-Light data model presents number of challenges and among them is identification of a test-session at Session-Reflector. A Session-Reflector MAY require only as little as its IP and UDP port number in received TWAMP-Test packet to spawn 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 run TWAMP 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 use of [I-D.ietf-ippm-type-p-monitor] that will go undetected, but by using five-tuple instead of four-tuple as a key we can ensure that TWAMP test packets that are considered as differesnt test sessions follow the same path even in ECMP environments.
TBA
module twampLight {
namespace "urn:ietf:params:xml:ns:yang:ietf-twamp";
//namespace need to be assigned by IANA
prefix "twampLight";
import ietf-inet-types {
prefix inet;
}
organization
"IETF IPPM (IP Performance Metrics) Working Group";
contact
"draft-mirsky-ippm-twamp-light-yang@tools.ietf.org";
description "TWAMP Light Data Model";
revision "2015-07-06" {
description "Initial version. RFC5357 is covered,
including Appendix I and the Errata.";
}
feature sessionSenderLight {
description "This feature relates to the device functions as the
TWAMP Light Session-Sender.";
}
feature sessionReflectorLight {
description "This feature relates to the device functions as the
TWAMP Light Session-Reflector.";
}
grouping maintenanceStatistics {
leaf sentPackets {
config "false";
default 0;
type uint32;
}
leaf rcvPackets {
config "false";
default 0;
type uint32;
}
leaf lastSentSeq {
config "false";
default 0;
type uint32;
}
leaf lastRcvSeq {
config "false";
default 0;
type uint32;
}
}
grouping sessionLightParameters {
description "Parameters common among Session-Sender and
Session-Reflector.";
leaf senderIp {
type inet:ip-address;
}
leaf senderUdpPort {
type inet:port-number;
}
leaf reflectorIp {
type inet:ip-address;
}
leaf reflectorUdpPort {
type inet:port-number;
}
leaf dscp {
description "The DSCP value to be placed in the header of TWAMP
UDP
test packets generated by the Session-Sender. Whether
Session-Reflector uses this value depends upon its local
configuration.";
type inet:dscp;
}
}
container twampLightSessionSender {
if-feature sessionSender;
list testSession {
key "senderIp senderUdpPort reflectorIp reflectorUdpPort dscp";
ordered-by system;
status current;
description "This structure is a container of test session
managed objects.";
leaf numberOfPackets {
type uint32;
description "The overall number of UDP test packets to be
transmitted by the sender for this test session.";
}
leaf packetPaddingSize {
type uint32;
default 27;
description "Size of the Packet Padding. Suggested to run
Path MTU Discovery
to avoid packet fragmentation in IPv4
and packet backholing in IPv6.";
}
leaf sessionAuthenticationMode {
type enumeration {
enum unathenticated;
enum authenticated;
enum encrypted;
}
default unathenticated;
description "Authentication mode of the TWAMP Light test
session."
}
leaf interval {
type uint32 {
description "Time interval between transmission of two
consequitive pakcets in the test session.";
}
}
leaf senderSessionState {
type enumeration {
enum active {
description "Test session is active.";
}
enum ready {
description "Test session is idle.";
}
}
default ready;
config "false";
}
uses maintenanceStatistics;
uses sessionLightParameters;
}
}
container twampLightSessionReflector {
if-feature sessionReflector;
leaf refwait {
config "true";
type uint32 {
range 1..604800;
}
units seconds;
default 900;
description "REFWAIT(TWAMP test session timeout in seconds),
the default value is 900";
}
leaf reflectorLightMode {
type enumeration {
enum stateful {
status current;
description "When the Session-Reflector Light is stateful,
i.e. is aware of test session state.";
}
enum stateless {
status current;
description "when the Session-Reflector is statelss.";
}
}
default stateless;
status current;
description "Whether Session-Sender copies sequence number
of received TWAMP-Test packet, i.e. Stateless, or counts
reflected TWAMP-Test packets and restarts counter based on
external event.";
}
leaf dscpHandlingMode {
type enumeration {
enum copyReceivedValue {
status current;
description "Use DSCP value copied from received TWAMP
test packet of the test session.";
}
enum useConfiguredValue {
status current;
description "Use DSCP value configured for this test
session on the Session-Reflector.";
}
}
status current;
default copyReceivedValue;
description "Session-Reflector handling of DSCP:
- use value copied from received TWAMP-Test packet;
- use value explicitly configued.";
}
list testSession {
key "senderIp senderUdpPort reflectorIp reflectorUdpPort dscp";
ordered-by system;
status current;
description "This structure is a container of test session
managed objects.";
uses maintenanceStatistics;
uses sessionLightParameters;
}
}
}
}
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-light
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-light
namespace: urn:ietf:params:xml:ns:yang:ietf-twamp-light
prefix: twamp
reference: RFC XXXX
The configuration, state, action data defined in this document may be accessed via the NETCONF protocol [RFC6241]. SSH [RFC6242] is mandatory secure transport that is the lowest NETCONF layer. The NETCONF access control model [RFC6536] provides means to restrict access for particular NETCONF users to a pre-configured subset of all available NETCONF protocol operations and content.
But, in general, this TWAMP Light YANG module does not change any underlying security issues that already may exhist in [I-D.elteto-ippm-twamp-mib].
| [I-D.ietf-ippm-type-p-monitor] | Hedin, J., Mirsky, G. and S. Baillargeon, "Differentiated Service Code Point and Explicit Congestion Notification Monitoring in Two-Way Active Measurement Protocol (TWAMP)", Internet-Draft draft-ietf-ippm-type-p-monitor-02, May 2015. |