Specifications

ping mpls
MP-386
Cisco IOS Multiprotocol Label Switching Command Reference
January 2010
Usage Guidelines
Note It is recommended that you use the mpls oam global configuration command instead of this command.
Use the ping
mpls command to validate, test, or troubleshoot IPv4 LDP LSPs, IPv4 Resource
Reservation Protocol (RSVP) TE tunnels, and AToM VCs.
UDP Destination Address Usage
The destination address is a valid 127/8 address. You have the option to specify a single x.y.z-address or
a range of numbers from 0.0.0 to x.y.z, where x, y, and z are numbers from 0 to 255 and correspond to
the 127.x.y.z destination address.
The MPLS echo request destination address in the UDP packet is not used to forward the MPLS packet
to
the destination router. The label stack that is used to forward the echo request routes the MPLS packet
to the destination router. The 127/8 address guarantees that the packets are routed to the local host (the
default loopback address of the router processing the address) if the UDP packet destination address is
used for forwarding.
In addition, the destination address is used to adjust load balancing when the destination address of the
IP pa
yload is used for load balancing.
Time-to-Live Usage
The time-to-live value indicates the maximum number of hops a packet should take to reach its
destination. The value in the TTL field in a packet is decremented by 1 each time the packet travels
through a router.
For MPLS LSP ping, the TTL is a value after which the packet is discarded and an MPLS echo reply is
sen
t back to the originating router.
For MPLS multipath LSP traceroute, the TTL is a maximum time-to-live value and is used to discover
th
e number of downstream hops to the destination router. MPLS LSP traceroute incrementally increases
the TTL value in its MPLS echo requests (TTL = 1, 2, 3, 4, ...) to accomplish this.
Downstream Map TLVs
The presence of a downstream map in an echo request is interpreted by the responding transit (not egress)
router to include downstream map information in the echo reply. Specify the ttl and dsmap keywords to
cause TTL expiry during LSP ping to interrogate a transit router for downstream information.
Pseudowire Usage
The following keywords are not available with the ping mpls pseudowire command:
• dsmap
• flags
• force-explicit-null
Cisco IOS XE Release
2.
3
This command was updated with the segment keyword.
12.2(33)SRE This command was modified. Restrictions were added to the pseudo
wire
keyword.
Release Modification