Mpls Oam Configuration; Function Introduction; Figure 33 Lsp Trace Working Principle - Zte ZXR10 8900 Series User Manual

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C h a p t e r
MPLS OAM
Configuration
Table of Contents

Function Introduction .........................................................65

Configure MPLS OAM..........................................................66
Function Introduction
MPLS TRACE/PING is used to detect MPLS LSP data plane fault.
It is quite simple and practical. Router in internet can be used to
report MPLS LSP data plane errors or provide information about
unexpected events. This method can discover and isolate black
hole routes, route loss, or other faults in short time.
MPLS TRACE/PING is an error report mechanism. It simulates
ICMP request and response mechanism to finally locate network
fault. Working principle of MPLS TRACE/PING is shown in Figure
33.
F 33 LSP TRACE W P
IGURE ORKING RINCIPLE
When initiating an LSP TRACE/PING request from LSR1, the desti-
nation is FEC (Forwarding Equivalence Class) in LSR6 and the route
is shown in Figure 33. Firstly, LSR1 sends an MPLS echo request
to LSR2. Since TTL field in outer tag is 1, after receiving this re-
quest, LSR2 finds that destination is not him. Therefore, it replies
an MPLS echo reply packet with return to be 6. After receiving re-
ply packet, LSR1 learns address of LSR2. LSR1 sends MPLS echo
requests whose TTL values increment by 1. After receiving such
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