Initiate a Layer 2 Traceroute

Note

Note

This procedure does not apply to XA1400 Series.

Use this procedure to trigger a Layer 2 traceroute. This feature enables CFM to debug Layer 2 in an SPBM cloud or network. It can determine the path used by IS—IS to get from one MEP to another, by showing all the hops between. Therefore, it can show where connectivity is lost. It can also work for IP shortcuts.

If you configure IsTraceTree to false then EDM performs Traceroute on the unicast path. If you configure IsTraceTree to true then EDM performs TraceTree on the multicast tree.

For more information on configuring tracetree, see Configure a Layer 2 Tracetree.

Important

Important

To trace a route to a MAC address, the MAC address must be in the VLAN FDB table.

For B-VLANs, you do not have to trigger an L2Ping to learn the MAC address because IS-IS populates the MAC addresses in the FDB table.

Linktrace traces the path up to the closest device to that MAC address that supports CFM.

Before you begin

  • On the source and destination nodes, you must configure a CFM MD, MA, and MEP, and assign a nodal MEP to the B-VLAN.

Procedure

  1. In the navigation pane, expand Configuration > Edit > Diagnostics.
  2. Select L2Ping/L2Trace Route.
  3. Select the L2 Traceroute/TraceTree tab.
  4. To start the traceroute, highlight an entry, and then select Start.
  5. To update the traceroute, select Refresh.
  6. To stop the traceroute, select Stop.

L2 Traceroute Field Descriptions

Use the data in the following table to use the L2 Traceroute/TraceTree tab.

Name

Description

VlanId

Specifies a value that uniquely identifies the Backbone VLAN (B-VLAN).

Priority

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

DestMacAddress

Specifies the target MAC address.

HostName

Specifies the target host name.

DestIsHostName

Specifies whether the host name is (true) or is not (false) used for the L2Trace transmission.

Isid

Specifies the Service Instance Identifier (I-SID).

IsTraceTree

Specifies whether the multicast tree or unicast path is traced:

  • If you configure IsTraceTree to false then EDM performs Traceroute on the unicast path.

  • If you configure IsTraceTree to true then EDM performs TraceTree on the multicast tree.

Status

Indicates the status of the transmit loopback service:

  • ready: the service is available.

  • transmit: the service is transmitting, or about to transmit, the L2Trace messages.

  • abort: the service aborted or is about to abort the L2Trace messages.

This field is also used to avoid concurrency or race condition problems that can occur if two or more management entities try to use the service at the same time.

The default is ready.

ResultOk

Indicates the result of the operation:

  • true: the L2Trace messages will be (or have been) sent.

  • false: the L2Trace messages will not be sent.

The default is true.

Ttl

Specifies the number of hops remaining to this L2Trace.

This value is decremented by 1 by each Bridge that handles the L2Trace. The decremented value is returned in the L2Trace. If 0 on output, the L2Trace is not transmitted to the next hop. The value of the time-to-live (TTL) field in the L2Trace is defined by the originating MEP.

The default value is 64.

SourceMode

Specifies the source mode:

  • 1: 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.

  • 2: smltVirtual—Use this value with B-VLANs only.

The default is 1: nodal.

SeqNumber

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

Flag

L2Trace result flag that indicates L2Trace status or error code:

  • none (1): No error

  • internalError (2): L2Trace internal error

  • invalidMac (3): Invalid MAC address

  • mepDisabled (4): MEP must be enabled in order to perform L2Trace

  • noL2TraceResponse (5): No L2Trace response received

  • l2TraceToOwnMepMac (6): L2Trace to own MEP MAC is not sent

  • l2TraceComplete (7): L2Trace completed

  • l2TraceLookupFailure (8): Lookup failure for L2Trace

  • l2TraceLeafNode (9): On a leaf node in the I-SID tree

  • l2TraceNotInTree (10): Not in the I-SID tree

  • l2TraceSmltNotPrimary (11): Requested SMLT source from non-primary node
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