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Pinging LSPs

 

The following sections describe how to use the ping mpls command to confirm LSP functioning.

Pinging MPLS LSPs

You can ping a specific LSP. Echo requests are sent over the LSP as MPLS packets. The payload is a User Datagram Protocol (UDP) packet forwarded to an address in the 127/8 range (127.0.0.1 by default, this address is configurable) and port 3503. The label and interface information for building and sending this information as an MPLS packet is the same as for standard LSP traffic.

When the echo request arrives at the egress node, the receiver checks the contents of the packet and sends a reply containing the correct return value, by using UDP. The router sending the echo request waits to receive an echo reply after a timeout of 2 seconds (you cannot configure this value).

You must configure MPLS at the [edit protocols mpls] hierarchy level on the remote router to be able to ping an LSP terminating there. You must configure MPLS even if you intend to ping only LDP forwarding equivalence classes (FECs).

To ping an MPLS LSP use the ping mpls <count count> <ldp <fec>> <rsvp <exp forwarding-class> <lsp-name>> command. To ping a secondary MPLS LSP, use the ping mpls <count count> <rsvp <lsp-name>> standby path-name command. For a detailed description of this command, see the CLI Explorer.

Nota

The ping mpls command is not supported within routing instances.

Nota

Self-ping is supported for the master instance and not supported for VLAN-based LSPs or LSPs used in CCC. The message is displayed for each LSP and reduces the readability of the configuration.

Pinging Point-to-Multipoint LSPs

To ping a point-to-multipoint LSP, use the ping mpls rsvp lsp-name multipoint or ping mpls rsvp egress address commands. The ping mpls rsvp lsp-name multipoint command returns a list of all of the egress router identifiers and the current status of the point-to-multipoint LSP egress routers. The ping mpls rsvp lsp-name multipoint egress address command returns the current status of the specified egress router.

Pinging the Endpoint Address of MPLS LSPs

To determine whether an LSP between two provider edge (PE) routers is up and running, you can ping the endpoint address of the LSP. To ping an MPLS LSP endpoint, use the ping mpls lsp-end-point address command. This command tells you what type of LSP (RSVP or LDP) terminates at the address specified and whether that LSP is up or down.

For a detailed description of this command, see the CLI Explorer.

Pinging CCC LSPs

You can ping a specific CCC LSP. The CCC LSP ping command is identical to the one used for MPLS LSPs. The command you use is ping mpls <count count> <rsvp <lsp-name>>. You can also ping a secondary standby CCC LSP by using the ping mpls <count count> <rsvp <lsp-name>> standby path-name command.

For a detailed description of this command, see the CLI Explorer.

Pinging Layer 3 VPNs

You can use a similar command, ping mpls l3vpn vpn-name prefix prefix <count count>, to ping a Layer 3 VPN. For more information about this command, see the Junos OS VPNs Library for Routing Devices and the CLI Explorer.

Support for LSP Ping and Traceroute Commands Based on RFC 4379

The Junos OS supports LSP ping and traceroute commands based on RFC 4379, Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures.

LSP ping and traceroute commands based on RFC 4379 attempt to trace the path taken by an LSP by relying on MPLS TTL expiration. An LSP can take multiple paths from ingress to egress. This occurs in particular with Equal Cost Multipath (ECMP). The LSP traceroute command can trace all possible paths to an LSP node.