Trigger a Loopback Test

Use this procedure to trigger a loopback test.

The LBM packet is often compared to ping. An MEP transmits the loopback message to an intermediate or endpoint within a domain for the purpose of fault verification. This can be used to check the ability of the network to forward different sized frames.

Before you begin

  • On the source and destination nodes, you must configure a CFM MD, MA, and MEP.

  • Enable the MEP.

  • Assign a nodal MEP to the B-VLAN.

Procedure

  1. In the navigation pane, expand Configuration > Serviceability > Diagnostics.
  2. Click CFM.
  3. Click the LBM tab.
  4. Configure the loopback test properties as required.
  5. Click Apply.
  6. To trigger the loopback test, double-click in the Status field, select transmit.
  7. Click Apply.
  8. To update the loopback test, click the Refresh button.

LBM Field Descriptions

Use the data in the following table to use the LBM tab.

Name

Description

DomainIndex

Specifies the MD index value.

AssociationIndex

Specifies the MA index value.

Index

Specifies the Maintenance Endpoint index value.

DomainName

Specifies the MD name.

AssociationName

Specifies the MA name.

DestMacAddress

Specifies the remote MAC address to reach the MEP/MIP.

Messages

Specifies the number of loopback messages to be transmitted. The default is 1.

VlanPriority

Specifies the priority. The default is 7.

SeqNumber

Specifies the transaction identifier/sequence number of the first loopback message (to be) sent. The default is 0.

ResultOk

Indicates the result of the operation:

  • true: The Loopback Messages will be (or have been) sent.

  • false: The Loopback Messages will not be sent.

The default is true.

Status

Indicates the status of the transmit loopback service:

  • ready: The service is available.

  • transmit: The service is transmitting, or about to transmit, the Loopback messages.

  • abort: The service is aborted or about to abort the Loopback messages.

The default is ready.

Result

Displays the LBM result.

TimeoutInt

Specifies the timeout interval in seconds. The default value is 3 seconds.

InterFrameInt

Specifies the interval between LBM frames with a range of (0..1000) msecs and a default value of 500 msecs. The value of 0 msecs indicates to send the frames as fast as possible. The default is 500.

TestPattern

Specifies the testfill pattern:

  • allZero — null signal without cyclic redundancy check

  • allZeroCrc — null signal with cyclic redundancy check with 32-bit polynomial

  • pseudoRandomBitSequence — pseudo-random-bit-sequence without cyclic redundancy check

  • pseudoRandomBitSequenceCrc — pseudo-random-bit-sequence with cyclic redundancy check with 32-bit polynomial.

A cyclic redundancy check is a code that detects errors. The default value is allZero.

DataSize

Specifies the data type-length-value (TLV) size. The default is 0.

FrameSize

Specifies the frame-size. The default is 0.

Sourcemode

Specifies the source mode of the transmit loopback service:

  • nodal

  • noVlanMac — Use this value with C-VLAN only. When you select this option, even if a VLAN MAC address exists, the system uses the CFM C-MAC as the BMAC-SA.

  • smltVirtual — Use the smltVirtual option with B-VLANs only.

The default is nodal.
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