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Configuring IP SLA MPLS LSP Ping and Trace Operations
Command or Action
Example:
RP/0/RSP0/CPU0:router(config-ipsla-sched)#
start-time 01:00:00
Step 15
commit
Step 16
show ipsla statistics [operation-number]
Example:
RP/0/RSP0/CPU0:router# show ipsla statistics 432
Configuring and Scheduling an MPLS LSP Trace Operation
An MPLS LSP trace operation traces the hop-by-hop route of LSP paths to a target router in an MPLS network
by sending echo requests (UDP packets) to the control plane of each transit label switching router (LSR). A
transit LSR performs various checks to determine if it is a transit LSR for the LSP path. A trace operation
allows you to troubleshoot network connectivity and localize faults hop-by-hop.
Echo request and reply packets validate the LSP. The success of an MPLS LSP trace operation depends on
the transit router processing the MPLS echo request when it receives a labeled packet.
The transit router returns an MPLS echo reply containing information about the transit hop in response to any
time-to-live (TTL)-expired MPLS packet or LSP breakage. The destination port of the MPLS echo reply is
set to the echo request source port.
In an MPLS LSP trace operation, each transit LSR returns information related to the type of Forwarding
Equivalence Class (FEC) entity that is being traced. This information allows the trace operation to check if
the local forwarding information matches what the routing protocols determine as the LSP path.
An MPLS label is bound to a packet according to the type of FEC used for the LSP. The following FEC types
are supported for an MPLS LSP trace operation:
• LDP IPv4 prefixes (configured with the target ipv4 command)
• MPLS TE tunnels (configured with the target traffic-eng tunnel command)
Cisco ASR 9000 Series Aggregation Services Router System Monitoring Configuration Guide, Release 4.2.x
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Implementing IP Service Level Agreements
Purpose
• (Optional) Use the pending keyword to configure
the operation to remain in a pending (unstarted) state.
The default value is inactive. If the start-time
command is not specified, no information is collected
until the start time is configured or a trigger occurs
that performs an immediate start.
• (Optional) Use the now keyword to indicate that the
operation should start immediately.
• (Optional) Use the after keyword and associated
arguments to specify the time after which the
operation starts collecting information.
Displays IP SLA statistics for the current MPLS LSP ping
operation.
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