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ping mpls ldp



Check the operability of MPLS LDP-signaled label-switched path (LSP) connections. Type Ctrl+c to interrupt a ping mpls command.


count count

(Optional) Number of ping requests to send. If count is not specified, five ping requests are sent. The range of values is 1 through 1,000,000. The default value is 5.

destination address

(Optional) Specify an address other than the default ( for the ping echo requests. The address can be anything within the 127/8 subnet.


(Optional) Display detailed information about the echo requests sent and received.

exp forwarding-class

(Optional) Value of the forwarding class for the MPLS ping packets.


Ping an LDP-signaled LSP using the forwarding equivalence class (FEC) prefix and length.

instance routing-instance-name

(Optional) Allows you to ping a combination of the routing instance and forwarding equivalence class (FEC) associated with an LSP.

logical-system (all | logical-system-name)

(Optional) Perform this operation on all logical systems or on the specified logical system.

p2mp root-addr ip-address lsp-id identifier

(Optional) Ping the end points of a point-to-multipoint LSP. Enter the IP address of the point-to-multipoint LSP root and the ID number of the point-to-multipoint LSP.

size bytes

(Optional) Size of the LSP ping request packet (88 through 65468 bytes). Packets are 4-byte aligned. For example, If you enter a size of 89, 90, 91, or 92, the router or switch uses a size value of 92 bytes. If you enter a packet size that is smaller than the minimum size, an error message is displayed reminding you of the 88-byte minimum.

source source-address

(Optional) IP address of the outgoing interface. This address is sent in the IP source address field of the ping request. If this option is not specified, the default address is usually the loopback interface (lo.0).


(Optional) Used for LDP to BGP stitched LSPs to specify the stitching protocol on an intermediate node. In the context of a ping mpls ldp command specify the stitching protocol as BGP, ISIS, or OSPF based on the configuration.


(Optional) Automatically determine the size of the maximum transmission unit (MTU).

Additional Information

If the LSP changes, the label and interface information displayed when you issued the ping command continues to be used. You must configure MPLS at the [edit protocols mpls] hierarchy level on the remote router or switch to ping an LSP terminating there. You must configure MPLS even if you intend to ping only LDP forwarding equivalence classes (FECs).

You can configure the ping interval for the ping mpls ldp command by specifying a new time in seconds using the lsp-ping-interval statement at the [edit protocols ldp oam] hierarchy level. For more information, see the MPLS Applications User Guide.

In asymmetric MTU scenarios, the echo response may be dropped. For example, if the MTU from System A to System B is 1000 bytes, the MTU from System B to System A is 500 bytes, and the ping request packet size is 1000 bytes, the echo response is dropped because the PAD TLV is included in the echo response, making it too large.


In a Juniper-Cisco interoperation network scenario, a point-to-multipoint LSP ping echo reply message from a Cisco device in a different IGP area is dropped on the Juniper device when the source address of the reply message is an interface address other than the loopback address or router ID. Starting in Junos OS Release 13.3X8, 14.2R6, 15.1R4, 15.1F6, 15.1F5-S8, 16.1R1, and later releases, such point-to-multipoint LSP ping echo reply messages are accepted by the Juniper device and the messages get logged as uncorrelated responses.

Required Privilege Level


Output Fields

When you enter this command, you are provided feedback on the status of your request. An exclamation point (!) indicates that an echo reply was received. A period (.) indicates that an echo reply was not received within the timeout period. An x indicates that an echo reply was received with an error code. Packets with error codes are not counted in the received packets count. They are accounted for separately.

Sample Output

ping mpls ldp fec count

ping mpls ldp p2mp root-addr lsp-id

Release Information

Command introduced before Junos OS Release 7.4.

size and sweep options introduced in Junos OS Release 9.6.

instance option introduced in Junos OS Release 10.0.

p2mp, root-address, and lsp-id options introduced in Junos OS Release 11.2.