PM session tests

Introduction

This section describes NFM-P supported PM OAM diagnostic test functionality. Unless noted, all tests are accessible from the STM. See  Table 90-1, NFM-P supported OAM diagnostic tests and configurations for a list of all supported OAM diagnostic tests and their applicable procedures.

PM session test support and configuration

The NFM-P supports PM session tests for Ethernet CFM, IP TWAMP Light, and MPLS DM.

You can configure PM session related objects from several areas in the NFM-P, including:

Ethernet CFM

PM session CFM testing is based on Metro Ethernet Forum Specification 35 - Service OAM Performance Monitoring Implementation Agreement, which details a standardized method to test and report network delay and loss using CFM messaging. This testing is performed in Layer 2 networks.

TWAMP IP level monitoring

The PM session testing framework can also be utilized in the IP domain to perform TWAMP (Two-Way Active Measurement Protocol) IP level monitoring, and runs over IPv4 and IPv6 addresses. The TWAMP Light and TCC tests target Layer 3 interfaces. They provide options to monitor IP SLA performance as related to KPI.

The TCA events and their associated statistics can be configured on all PM session test types.

PM session results

Results reporting occurs at standardized measurement intervals (5 minutes, 15 minutes, 1 hour, and 1 day), and comprises statistical summaries of individual test frame results. Statistical summaries include minimum, maximum, and average values of specific test criteria. SNMP-mediated statistics can be collected to display real-time results for in-progress measurement intervals. Additionally, a histogram can be generated to characterize the distribution of test results over the same measurement intervals. Statistics can be viewed using the individual test forms, the STM, or the Statistics Manager.

PM session test suite support

While PM session tests may be configured individually, test suite support allows for repeatable, policy driven auto-generation of PM sessions and associated tests, which are ideally suited to larger scale environments. See To create an STM test suite for information about how to configure PM session tests as part of an STM test suite.

CFM DMM session test

For CFM DMM (Delay Measurement Message) tests, calculations are made to report on three criteria: frame delay, frame delay range, and interframe delay variation. DMM test frames are issued at regular intervals from a source MEP. Delay measurement information for the forward, backward, and round trip path is determined from the DMR frames received from the destination MEP.

See To configure a CFM DMM session OAM diagnostic test from the STM for information about configuring a CFM DMM test.

CFM SLM session test

The CFM SLM (Synthetic Loss Measurement) session test is an extension of the Y.1731 standard that provides a method of exchanging transmit and receive counters to determine frame loss between a MEP and the destination MAC address or remote MEP ID of another node in the network. This test is used to verify MEP-MEP connectivity in the network and can be used to approximate the frame loss of actual data traffic. CFM SLM session tests measure frame loss using synthetic frames, rather than data traffic. Frame loss is measured by calculating the difference between the number of synthetic frames that are sent and received.

See To configure a CFM SLM session OAM diagnostic test from the STM for information about configuring a CFM SLM session test.

CFM LMM session test

The CFM LMM (Loss Measurement Message, single-ended) session test is a method of exchanging transmit and receive counters between peer MEPs to determine exact loss on a point-to-point Ethernet virtual circuit.

Note: LMM tests are limited to MEPs in the Down direction only. The following validations are performed:

See To configure a CFM LMM session OAM diagnostic test from the STM for information about configuring a PM CFM LMM test.

TWAMP Light session test

The TWAMP Light session test targets Layer 3 interfaces and requires a TWAMP reflector in order to execute properly. See To configure a TWAMP Light reflector .

You can configure a TWAMP Light session test on the following network objects:

TCC test

A TWAMP server is a combination of control server and session reflector, but requires an external probe called the TWAMP controller (testing head). The TWAMP Light test supports both a session sender and session reflector. TWAMP Light does not have a separate control plane, and the session reflector is configured in the NFM-P.

The TCC (TWAMP and TWAMP Light Control Client) test allows a TWAMP Light NE launch point (base router) to test TWAMP functionality against any TWAMP server that does not support TWAMP Light. The NFM-P creates the required TCP control channel with the TWAMP server, as well as the PM sessions and tests on the TWAMP Light launch point. The NFM-P also provides a report on a managed TWAMP server's capabilities (based on SNMP queries), which is accessible on the Globals→OAM sub-tab of the NE's properties form.

For managed RFC5938–compliant TWAMP servers, individual session control allows start and stop control messaging. This permits the client to define new tests and to start or stop specific tests while the TWAMP connection is active. The following operational points apply:

See To configure a TCC OAM diagnostic test from the STM for information about configuring a TCC test.

MPLS DM session test

The MPLS DM (Delay Measurement) session test is based on RFC 6374, and provides calculations for LSPs for frame delay, frame delay range, and interframe delay variation. Measurements are one-way for dynamic RSVP and RSVP-auto LSP types, and round-trip for MPLS-TP Static LSP types. Test frame intervals are configurable from 1000 to 8000 ms, in 1000 ms increments. As a security feature, a global setting in the NE properties must be enabled for test packets to be transmitted or reflected.

See To configure an MPLS DM session OAM diagnostic test from the STM for information about configuring an MPLS DM test.