Trigger Linktrace

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.

About this task

Use the following procedure to trigger a linktrace. The link trace message is often compared to traceroute. An MEP transmits the Linktrace Message packet to a maintenance endpoint with intermediate points responding to indicate the path of the traffic within a domain for the purpose of fault isolation. The packet specifies the target MAC address of an MP, which is the SPBM system ID or the virtual SMLT MAC. MPs on the path to the target address respond with an LTR.

Procedure

  1. In the navigation pane, expand Configuration > Serviceability > Diagnostics.
  2. Select CFM.
  3. Select the LTM tab.
  4. Configure the linktrace test properties as required.
  5. Select Apply.
  6. To trigger the linktrace test, perform one of the following actions:
    • In Status, select transmit, and then select Apply
    • Highlight an entry, and then select Start.
  7. To update the linktrace, select the Refresh button.
  8. To stop the linktrace, select Stop.

LTM Field Descriptions

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

Name

Description

DomainIndex

Specifies the MD index value.

AssociationIndex

Specifies the MA index value.

Index

Specifies the MEP index value.

DomainName

Specifies the MD name.

AssociationName

Specifies the MA name.

VlanPriority

Specifies the VLAN priority, a 3–bit value to be used in the VLAN tag, if present in the transmitted frame. The default is 7.

DestMacAddress

Specifies the remote MAC address to reach the MEP.

Ttl

Indicates the number of hops remaining to this LTM. This value is decremented by 1 by each bridge that handles the LTM. The decremented value is returned in the LTR. If the value is 0 on output, the LTM is not transmitted to the next hop. The value of the TTL field in the LTM is specified at the originating MEP. The default value is 64.

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 LTM messages.

  • abort: The service is aborted, or about to abort, the LTM message.

The default is ready.

Flag

Displays the LTM result flag indicating LTM status or error code. Each value represents a status or error case:

  • 1 - No error

  • 2 - LTM internal error

  • 3 - Unknown Remote Maintenance Endpoint

  • 4 - Invalid Remote Maintenance Endpoint MAC Address

  • 5 - Unset Remote Maintenance Endpoint MAC address

  • 6 - MEP must be enabled in order to perform LTM

  • 7 - No LTR response received

  • 8 - Linktrace to own MEP MAC is not sent

  • 9 - Endpoint must be enabled in order to perform LTM

  • 10 - Pbt-trunk must be enabled in order to perform LTM

  • 11 - LTM completed

  • 12 - LTM leaf node

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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