Ethernet CFM test descriptions
Introduction
This section provides a description of NFM-P supported Ethernet CFM OAM diagnostic tests. 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.
Global MEG check
A global MEG check detects connectivity failures between pairs of local and remote maintenance endpoints, or MEPs, in a MEG. A MEG consists of the maintenance entities that belong to the same service inside a common service OAM domain.
See To create and run a Global MEG OAM diagnostic test from the STM for information about how to create and run a global MEG check from the STM.
Continuity check
Continuity check messages are multicast messages that a MEP transmits periodically to remote MEPs in the same MEG. CCMs are used to discover a remote endpoint, check the health of a site, and detect cross-connect misconfigurations. A CFM continuity check test is automatically generated when you create an MD. When you execute the test and a connectivity fault is present, the MEP that detects the fault raises an alarm.
See To create and run a Continuity Check OAM diagnostic test from the STM for information about how to create and run a continuity check from the STM.
The loss of three consecutive CCMs or the receipt of a CCM with incorrect information, indicates a fault.
Note: If a service is modified after you associate it with an MD; for example, a new site is added, you must manually add new MEPs.
If a CFM continuity check test is running on a service when you add a new MEP to the service, you must stop the test and execute it again to make the new MEP active.
When a service is modified after a CFM continuity check is created; for example, a new B-VPLS site is added to the service, you must manually add a virtual MEP to the site.
CFM dual-ended loss test
A CFM dual-ended loss test functions as an optional extension of a CFM continuity check. It applies only to Y.1731 MEPs that are configured on the 7705 SAR. This type of test is used to calculate the rate of frame loss in each direction for Ethernet packets sent between two MEPs.
When a continuity check test is executed with the dual-ended loss option enabled, the option is replicated on all participating MEPs that support the test, along with the accompanying alarm threshold values. If a MEP detects that the local or remote frame loss ratio has exceeded the alarm threshold for a remote MEP, the MEP raises an alarm against the remote MEP.
See To create and run a Continuity Check OAM diagnostic test from the STM for information about how to configure the CFM dual-ended loss test option as part of creating and running a CFM continuity check from the STM.
CFM loopback
CFM loopback messages are sent to a unicast destination MAC address. The MEP at the destination responds to the loopback message with a loopback reply. A MEP or a MIP can reply to a loopback message if the destination MAC address matches the MAC address of the MEP or MIP. CFM loopback tests verify connectivity to a specific MEP or MIP.
See To create and run a CFM loopback OAM diagnostic test from the STM for information about how to create and run a CFM loopback from the STM.
You can also perform multicast loopbacks by providing a multicast address (class 1 multicast destination) that aligns with the level that the originating MEP is configured on. Only one multicast test can be run at a time per NE, and results from the previous test are deleted when a new test is started. The stored values include the responding MEP MAC address, the sequence number, and a locally-assigned rx index (allowing you to detect out-of-order responses).
CFM link trace
CFM link trace messages that contain a target unicast MAC address are sent to multicast destination MAC addresses. Each MIP at the same MD level replies with a link trace response. Messages are forwarded to the next hop until they reach the destination MAC address.
See To create and run a CFM link trace OAM diagnostic test from the STM for information about how to create and run a CFM link trace from the STM.
CFM Eth test
The CFM Eth test applies only to Y.1731 MEPs. This one-way test originates on a source MEP and terminates on a destination MEP. The target of a CFM Eth test is a MAC address. The test is used to perform one-way in-service diagnostic test that include verifying bandwidth throughput, frame loss, and bit errors. To perform the test, a MEP inserts frames with Eth-test information that includes specific throughput, frame size, and transmission patterns. A MIP is transparent to Eth-test frames.
See To create and run a CFM Eth OAM diagnostic test from the STM for information about how to create and run a CFM Eth test from the STM.
CFM two way delay test
The CFM two way delay test applies only to Y.1731 MEPs. In this test, the frame delay is defined as the time elapsed since the start of transmission of the first bit of the frame by the source site until the frame is received by the same site after passing through the destination site. The frame delay represents the round-trip time between the source and destination sites.
See To create and run a CFM two way delay OAM diagnostic test from the STM for information about how to create and run a CFM two way delay test from the STM.
CFM one way delay test
The CFM one way delay test applies only to Y.1731 MEPs. The test originates on one MEP and terminates on a target MEP. The results are read from the target MEP. In the test, frame delay is defined as the time elapsed since the start of transmission of the first bit of the frame by a source site until the frame is received by the destination site. The frame delay represents the one-way trip time between the source and destination sites.
See To create and run a CFM one-way delay OAM diagnostic test from the STM for information about how to create and run a CFM one way delay test from the STM.
CFM single ended loss test (7705 SAR only)
The CFM single ended loss test applies only to Y.1731 MEPs. This one-way test originates on a source MEP and terminates on a destination MEP. The target of a single-ended loss test is a destination MAC address. The test is used to calculate the rate of frame loss in each direction for Ethernet packets sent between the two MEPs.
See To create and run a CFM single-ended loss OAM diagnostic test from the STM for information about how to create and run a CFM single ended loss test from the STM.
CFM two way SLM
The CFM two way SLM test provides Synthetic Loss Measurement and is used to check packet loss for a particular MEP. See To create and run a CFM two way SLM OAM diagnostic test from the STM for information about how to create and run a CFM two way SLM test from the STM.
Note: On the 7705 SAR, SLM is only supported on Epipe services under the following conditions:
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single-ended (two way) loss measurement using optional TLV with a timestamp on the near-end and far-end for combined loss and delay measurement
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DOWN MEP direction for Spoke-SDPs only (UP and DOWN MEP direction for SAPs)
CFM LM test
The CFM LM (loss measurement) test measures the counter values applicable for ingress and egress service frames where the counters maintain a count of transmitted and received data frames between a pair of MEPs.
See To create and run a CFM LM OAM diagnostic test from the STM for information about how to create and run a CFM LM test from the STM.
CFM Statistics
The Ethernet CFM statistics are used for viewing and analyzing the current overall processing requirements for CFM. Any packet that is counted against the CFM resource will be included in the statistics counters.
The Ethernet CFM statistics are available per NE and per MEP, with a per-OpCode breakdown. Use the show eth-cfm statistics command to display the statistics at the system level. Use the show eth-cfm mep mep-id domain md-index association ma-index statistics command to view the per-MEP statistics.
From the NFM-P GUI, Ethernet CFM statistics can be retrieved:
For ETH-CFM statistics at the NE level, the record types include:
At the individual MEP level, CFM Opcodes → OAM_MEP_statistics can be displayed. Click Resync to see the changes in the NFM-P.
These statistics help operators to determine the busiest active MEPs on the system with a breakdown of per-OpCode processing at the system and MEP level. For eth-cfm oper up statistics collection, create an MD and a MEG and attach a service with up/down MEP. See To configure an automatic MEP ID assignment on an NE and To configure an Ethernet CFM MD policy and subordinate objects.