Configuring Lsp Trace - Zte ZXR10 ZSR V2 Configuration Manual (System Management

Run the following command on R1 to test connectivity. The execution result is
displayed as follows:
R1#ping mpls pseudowire pw1
sending 5,120-byte MPLS echo(es) to 10.28.0.4,timeout is 2 second(s).
Codes: '!' - success,
ut,
ismatch,
label,
wn return code, 'x' - return code 0
!!!!!
Success rate is 100 percent(5/5),round-trip min/avg/max= 2/2/2 ms.

15.8 Configuring LSP Trace

Overview
l Description of LSP Trace
To make routers on the Internet report errors of the MPLS LSP data plane or provide
information on unexpected conditions, the MPLS trace function is provided. MPLS
trace is a simple and effective method of detecting faults on the MPLS LSP data plane.
It can detect some faults that the control plane cannot find. By using this method,
users can quickly find and isolate faults such as routing black holes and loss of routes.
LSP trace is based on Echo Request and Echo Reply packets. The packets sent are
UDP packets whose port number is 3503 instead of ICMP packets.
LSP trace uses the TTL field in an MPLS packet header. The LSP trace command
increments the TTL value from 1, and sends an MPLS Echo Request packet to the
next hop. When detecting that TTL expires, an LSR sends an MPLS Echo Reply
packet to the source. In such a query procedure, each hop of an LSP can be traced.
l
Work Flow of LSP Trace
The LSP trace function can be used to detect different FECs (IPv4 LDP and RSVP).
An LSP trace request packet is a UDP packet with a label. The packet uses the
well-known port 3503 as the destination port. The source port is designated by the
sender. The IP-layer source address is the IP address of the sender. The destination
address is 127.0.0.1, which is used to prevent the packet from being forwarded
according to an IP route when a fault occurs on an LSP of an intermediate LSR.
The principle of LSP trace is shown in
SJ-20140504150128-007|2014-05-10 (R1.0)
'L' - labeled output interface, 'B' - unlabeled output interface,
'D' - DS Map mismatch,
'M' - malformed request,
'P' - no rx intf label prot,
'R' - transit router,
'd' - DDMAP
Chapter 15 Network Layer Detection
'Q' - request not sent,
'F' - no FEC mapping,
'm' - unsupported tlvs,
'p' - premature termination of LSP,
'I' - unknown upstream index, 'X' - unkno
Figure 15-13.
15-21
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'.' - timeo
'f' - FEC m
'N' - no rx