Mpls Basic Configuration Guide, Cisco Ios Xe Everest 16.5.1 (Cisco Asr 900 Series - Cisco ASR 900 Series Manual

MPLS LSP Ping, Traceroute, and AToM VCCV
The figure below shows the echo request and echo reply paths for MPLS LSP Ping.
Figure 6: MPLS LSP Ping Echo Request and Echo Reply Paths
If you initiate an MPLS LSP Ping request at LSR1 to a Forwarding Equivalence Class (FEC), at LSR6, you
get the results shown in the table below .
Table 4: MPLS LSP Ping Example
Step
1
1
1
1
1
1
Device
LSR1
LSR2
LSR5
LSR6
LSR7 to LSR10
LSR1

MPLS Basic Configuration Guide, Cisco IOS XE Everest 16.5.1 (Cisco ASR 900 Series)

MPLS LSP Ping Operation
Action
Initiates an MPLS LSP Ping
request for an FEC at the target
device LSR6 and sends an MPLS
echo request to LSR2.
Receives and forwards the MPLS
echo request packet through transit
devices LSR3 and LSR4 to the
penultimate device LSR5.
Receives the MPLS echo request,
pops the MPLS label, and forwards
the packet to LSR6 as an IP packet.
Receives the IP packet, processes
the MPLS echo request, and sends
an MPLS echo reply to LSR1
through an alternate route.
Receive and forward the MPLS
echo reply back toward LSR1, the
originating device.
Receives the MPLS echo reply in
response to the MPLS echo
request.
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