Hi,
I hope this will help you understand the meaning of the commands:
LSP Ping
MPLS LSP ping uses MPLS echo request and reply packets, similar to Internet Control Message Protocol
(ICMP) echo request and reply messages, to validate an LSP. ICMP echo request and reply messages validate
IP networks; MPLS OAM echo and reply messages validate MPLS LDP networks. The LSP ping and trace
functions use IPv4 UDP packets with UDP port number 3503. You can use MPLS LSP ping to validate IPv4
LDP or Forwarding Equivalence Classes (FECs) by using the ping mpls privileged EXEC command. The
MPLS echo request packet is sent to a target router by using the label stack associated with the FEC to be
validated.
resources:
https://www.cisco.com/c/en/us/td/docs/wireless/asr_901/Configuration/Guide/b_asr901-scg/b_asr901-scg_chapter_010001.pdf
reply mode [ ipv4 | router-alert | no-reply ] | Specifies the reply mode for the echo request packet. no-reply Do not reply ipv4 Reply with an IPv4 UDP packet (this is the default)
router-alert Reply with an IPv4 UDP packet with the IP router alert set |
resources:
https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/mpls/b-mpls-cr-ncs5500/b-ncs5500-mpls-cli-reference_chapter_0110.html
Return code 4 sent due to some error condition either of the following has occurred:
- Wrong VC ID
- Wrong VC Type
- Wrong Source Address
resources (page 63):
https://archive.nanog.org/meetings/nanog33/presentations/moizuddin.pdf
reply mode control-channel
this pings the PW part only from one tunnel end point to the other and does not touch to the AC part of the circuit
