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traceroute mpls ldp



Trace route to a remote host for an MPLS label-switched path signaled by the LDP. Use traceroute mpls ldp as a debugging tool to locate MPLS label-switched path forwarding issues in a network. (Currently supported for IPv4 packets only.)



Specify the IP address and optional prefix of the forwarding equivalence class (FEC).

destination ip-address

(Optional) Specify the destination address to use when sending probes.

  • Values: The destination IP address must be within the IP address space for Operation, Administration, and Maintenance (OAM) packets.


(Optional) Display detailed output.

exp exp

(Optional) Specify the class-of-service to use when sending probes.

  • Range: 0 through 7

  • Default: 7

fanout fanout-number

(Optional) Specify the maximum number of nexthops to search per node.

  • Range: 1 through 16

  • Default: 16


(Optional) Specify the name of the logical system for the traceroute attempt.


(Optional) Specify not to resolve the hostname that corresponds to the IP address.

paths maximum-paths

(Optional) Specify the maximum number of paths to search.

  • Range: 1 through 255

  • Default: 16


(Optional) Specify to trace only nodes that understand LDP FEC.

In an interoperation with other vendor devices or devices running Junos OS Release that do not support tracing of hierarchical LSPs as described in RFC 6424, continuous non-complaint probe status is displayed in the traceroute mpls ldp command output. To avoid this LDP loop creation, use the pipe-mode option with the traceroute mpls ldp fec command.


Even after using the traceroute mpls ldp fec pipe-mode command, one or more intermediate transit nodes that do not understand LDP FEC can return non-complaint probe status in the command output.

retries retries-number

(Optional) Specify the number of times to resend probe values.

  • Range: 1 through 9

  • Default: 3

routing-instance routing-instance-name

(Optional) Specify the name of the routing instance for the traceroute attempt.

source source-address

(Optional) Specify the source address of the outgoing traceroute packets.

ttl value

(Optional) Specify the maximum time-to-live value to include in the traceroute request, in seconds.

  • Range: 1 through 125

  • Default: 64


(Optional) Update database contents with traceroute results.

wait seconds

(Optional) Specify the number of seconds to wait before resending a probe.

  • Range: 5 through 15

  • Default: 10

Required Privilege Level


Output Fields

Table 1 describes the output fields for the traceroute mpls ldp fec command and the traceroute mpls ldp fec detail commands. Output fields are listed in the approximate order in which they appear.

Table 1: traceroute mpls ldp Output Fields

Field Name

Field Description

Level of Output

Probe options

Probe options specified in the traceroute mpls ldp fec command.

all levels


Time to live value of the labeled packet.

none specified


Outgoing label used for forwarding the packet along the label-switched paths.

none specified


Signaling protocol used. For this command, it is LDP.

none specified


Address of the next hop.

none specified

Previous Hop

Address of the previous hop. Previous hop address of the first hop is null.

none specified

Probe status

Forwarding status from the first hop to the last-hop label-switching router (egress point in the label-switched paths).

none specified


Address of the hops in the label-switched path from the first hop to the last hop. Depth indicates the level of the hop.



Address of the previous hop. Parent value for the first hop is null.


Return Code

Return code for reporting the result of processing the echo request by the receiver.


Response time

Time for the echo request to reach the receiver.


Multipath type

Labels or addresses used by the specified multipath type. If multipaths are not used, the value is none.


Label Stack

Label stack used to forward the packet.


Sample Output

traceroute mpls ldp

traceroute mpls ldp detail

Release Information

Command introduced in Junos OS Release 8.4.