Example 1115 show mpls trafficeng tunnel tunnel1 on 7200a Under Normal Circumstances

7200a#show mpls traffic-eng tunnels tunnel1

Name: Primary tunnel 7200a->12008a->12... (Tunnell) Destination: 12.12.12.12 Status:

Admin: up Oper: up Path: valid Signalling: connected path option 5, type explicit primary (Basis for Setup, path weight 3) path option 6, type dynamic

Config Parameters:

Bandwidth: 100 kbps (Global) Priority: 7 7 Affinity: 0x0/0xFFFF

Metric Type: TE (default)

AutoRoute: enabled LockDown: disabled Loadshare: 100 bw-based auto-bw: disabled

InLabel : -OutLabel : POS3/0, 12305

RSVP Signalling Info:

Src 4.4.4.4, Dst 12.12.12.12, Tun_Id 1, Tun_Instance 260 RSVP Path Info:

Explicit Route: 10.0.3.5 10.0.5.11 10.0.17.12 12.12.12.12 Record Route: NONE

Tspec: ave rate=100 kbits, burst=1000 bytes, peak rate=100 kbits RSVP Resv Info:

Record Route: NONE

Fspec: ave rate=100 kbits, burst=1000 bytes, peak rate=Inf Shortest Unconstrained Path Info: Path Weight: 3 (TE)

Explicit Route: 10.0.3.5 10.0.5.11 10.0.17.12 12.12.12.12 History: Tunnel:

Time since Time since Current LSP:

Uptime: 1 minutes, 9 seconds Prior LSP:

ID: path option 5 [259] Removal Trigger: tunnel shutdown

In this case, the path is valid.

The text at the bottom of the output is highlighted to call your attention to the History section of the output. The History section is a good place to start looking if path is invalid. As you can see, it has the reason why the tunnel was last removed—because of tunnel shutdown.

You'll find several cases that might cause the path to be invalid:

• Case A— Multiple constraints are placed on the tunnel. Removing some of them brings the tunnel up.

• Case B— One or more constraints on the tunnel, and only when you remove all of them does the tunnel come up.

• Case C— There are no paths to the destinations, constrained or unconstrained, and even when you remove all the constraints on the tunnel, it still stays down.

NOTE

Constraints are things configured on the headend that can cause the TE tunnel path to diverge from the IGP shortest path. Specifically, the available TE constraints are bandwidth, affinity/link attributes, priority, and path option. An unconstrained path is the path that the TE tunnel would take with no constraints—essentially, the IGP path.

created: 1 days, 1 minutes path change: 1 minutes, 9 seconds

Case A: Removing Some Constraints Brings Up the Tunnel Consider Example 11-16, in which the path is invalid. Example 11-16 Path on tunnel1 on 7200a Is Invalid

7200a#show mpls traffic-eng tunnels tunnel1

Name: Primary tunnel 7200a->12008a->12... (Tunnell) Destination: 12.12.12.12 Status:

Admin: up Oper: down Path: not valid Signalling: Down path option 5, type explicit primary

Config Parameters:

Bandwidth: 100 kbps (Global) Priority: 7 7 Affinity: 0x0/0xFFFF

Metric Type: TE (default)

AutoRoute: enabled LockDown: disabled Loadshare: 100 bw-based auto-bw: disabled

Shortest Unconstrained Path Info: Path Weight: 3 (TE)

Explicit Route: 10.0.3.5 10.0.5.11 10.0.17.12 12.12.12.12 History: Tunnel:

Time since created: 1 days, 44 minutes Time since path change: 23 minutes, 5 seconds Prior LSP:

Removal Trigger: path verification failed

Last Error: PCALC:: Can't use link 10.0.3.5 on node 5.5.5.5

You need to notice a few facts from the highlighted output of Example 11-16:

• The tunnel is operationally down, and the path is invalid.

• Only one path option is configured on the tunnel, and it is explicit.

• The shortest unconstrained path matches the explicitly specified path that was shown earlier, in Example 111.

• The Last Error field in the History section says PCALC:: Can't use link 10.0.3.5 on node 5.5.5.5.

If the shortest unconstrained path is the same as the specified explicit path and the path is invalid, this can mean only one thing—the constraints placed on the tunnel cannot be satisfied along the explicitly specified path.

You can do one of the following things to fix this problem:

• Remove the bandwidth constraints and keep the explicit path option

• Keep the bandwidth constraints and remove the explicit path option that brings up the tunnel NOTE

Using an explicit path option is also a type of constraint, because you are asking the headend to build the tunnel using an explicitly specified path list.

Removing Bandwidth Constraints While Keeping the Explicit Path Option

Tunnel1 comes up after you remove the bandwidth constraint but use the same explicit path option. Example 11-17 demonstrates this.

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