Initiate a Layer 2 Traceroute

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

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

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

L2 Traceroute/TraceTree 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: The default is 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