Using MPLS Ping
Use the MPLS ping functionality to diagnose the state of label-switched paths (LSPs), Layer 2 and Layer 3 virtual private networks (VPNs), and Layer 2 circuits. You can ping an MPLS endpoint using various options. You can send variations of ICMP echo request packets to the specified MPLS endpoint.
When you use the ping MPLS task from a Junos OS operating as the inbound (ingress) node at the entry point of an LSP or VPN, the routing platform sends probe packets into the LSP or VPN. Based on how the LSP or VPN outbound (egress) node at the remote endpoint of the connection replies to the probes, you can determine the connectivity of the LSP or VPN.
Each probe is an echo request sent to the LSP or VPN exit point as an MPLS packet with a UDP payload. If the outbound node receives the echo request, it checks the contents of the probe and returns a value in the UDP payload of the response packet. If the Junos OS receives the response packet, it reports a successful ping response.
Responses that take longer than 2 seconds are identified as failed probes.
Table 1 lists the ping MPLS tasks, summarizes their functions, and identifies corresponding CLI show commands you can enter in the CLI interface of a device.
Table 1: Ping MPLS Tasks Summary and the Corresponding CLI show Commands
Ping MPLS Task | Corresponding CLI Command | Function | Additional Information |
|---|---|---|---|
Ping RSVP-signaled LSP | ping mpls rsvp | Checks the operability of an LSP that has been set up by the Resource Reservation Protocol (RSVP). The Junos OS pings a particular LSP using the configured LSP name. | When an RSVP-signaled LSP has several paths, the Junos OS sends the ping requests on the path that is currently active. |
Ping LDP-signaled LSP | ping mpls ldp | Checks the operability of an LSP that has been set up by the Label Distribution Protocol (LDP). The Junos OS pings a particular LSP using the forwarding equivalence class (FEC) prefix and length. | When an LDP-signaled LSP has several gateways, the Junos OS sends the ping requests through the first gateway. Ping requests sent to LDP-signaled LSPs use only the master routing instance. |
Ping LSP to Layer 3 VPN prefix | ping mpls l3vpn | Checks the operability of the connections related to a Layer 3 VPN. The Junos OS tests whether a prefix is present in a provider edge (PE) router's VPN routing and forwarding (VRF) table, by means of a Layer 3 VPN destination prefix. | The Junos OS does not test the connection between a PE router and a customer edge (CE) router. |
Ping LSP for a Layer 2 VPN connection by interface | ping mpls l2vpn interface | Checks the operability of the connections related to a Layer 2 VPN. The Junos OS directs outgoing request probes out the specified interface. | For information about interface names, see the CLI Explorer. |
Ping LSP for a Layer 2 VPN connection by instance | ping mpls l2vpn instance | Checks the operability of the connections related to a Layer 2 VPN. The Junos OS pings on a combination of the Layer 2 VPN routing instance name, the local site identifier, and the remote site identifier, to test the integrity of the Layer 2 VPN circuit (specified by the identifiers) between the inbound and outbound PE routers. | |
Ping LSP to a Layer 2 circuit remote site by interface | ping mpls l2circuit interface | Checks the operability of the Layer 2 circuit connections. The Junos OS directs outgoing request probes out the specified interface. | |
Ping LSP to a Layer 2 circuit remote site by VCI | ping mpls l2circuit virtual-circuit | Checks the operability of the Layer 2 circuit connections. The Junos OS pings on a combination of the IPv4 prefix and the virtual circuit identifier on the outbound PE router, testing the integrity of the Layer 2 circuit between the inbound and outbound PE routers. | |
Ping end point of LSP | ping mpls lsp-end-point | Checks the operability of an LSP endpoint. The Junos OS pings an LSP endpoint using either an LDP FEC prefix or an RSVP LSP endpoint address. |