This section provides a quick overview of some of the commands that are useful for troubleshooting MPLS TE problems. Table 11-3 summarizes these commands. Not all debug or show commands are shown here; there are too many to list. However, these are the major ones.
Table 11-3. Useful Commands for MPLS TE Troubleshooting
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show running-config [modifier]
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Headend, midpoint, tail
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This command can be used to verify the different configurations on any LSR regardless of the LSR's role.
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show mpls traffic-eng tunnel summary [modifier]
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Headend, midpoint, tail
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This command displays the following information:
If the LSP tunnel process is running If the RSVP process is running If forwarding is enabled Periodic reoptimization Periodic FRR promotion Periodic auto bandwidth collection Role of this LSR for various LSPs (how many LSPs this LSR is headend/midpoint/tail for)
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show ip cef summary
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Headend, midpoint, tail
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Used to check if CEF is enabled on an LSR.
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show ip interface brief
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Headend, midpoint, tail
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On the headend, checks both the tunnel state and the outbound interfaces. At the midpoints and tail, displays the state of inbound/outbound physical interfaces.
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show mpls traffic-eng tunnels brief
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Headend, midpoint, tail
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Can be used to obtain any information that is available using show mpls traffic-eng summary. In addition, you can use it to check the state of any tunnels for which this router is a head, mid, or tail.
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show mpls traffic-eng tunnels tunnel
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Headend
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Although this command can be executed on midpoints and tail, it is one of the most useful commands for determining why a tunnel is not coming up.
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show mpls traffic-eng link-management [interfaces | admission-control | advertisements | statistics]
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Midpoint, tail
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Used to check the advertisements out a link at midpoints or the tail.
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show ip rsvp [interface | sender | request | reservation]
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Headend, midpoint, tail
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Checks signalling details and whether RSVP is configured on interfaces.
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show ip rsvp counters
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Headend, midpoint, tail
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Checks how many signalling attempts were made, how many times an RSVP session was established, and the number of activations and deactivations.
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show mpls traffic-eng topology [TE-ID | path | area | level-1 | level-2]
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Headend
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Even though the contents of the topology should be the same everywhere, this command should be executed at the headend to examine the contents of the TE database (TE-DB) to verify CSPF manually.
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show ip ospf database opaque-area
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Headend, midpoint, tail
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Used to check the actual TE-LSAs received by this LSR.
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show isis mpls traffic-eng advertisements
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Headend, midpoint, tail
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Used to check the actual TE-LSAs received by this LSR.
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debug ip rsvp [path | resv]
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Headend, midpoint, tail
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Used to obtain RSVP signalling information between neighbors.
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debug mpls traffic-eng path lookup
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Headend
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Shows the verification of an explicit path prior to signalling that path.
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debug mpls traffic-eng path spf
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Headend
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Shows the CSPF process that the headend goes through when operating on the path-option dynamic.
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The following section provides detailed information on how to go about finding what exactly is wrong and how to fix it.
