mplsGlobal Config

mpls traffic-eng

Enables MPLS Traffic Engineering (MPLS-TE) and enters MPLS-TE configuration submode on Cisco IOS-XR.

Overview

The 'mpls traffic-eng' command is the gateway to configuring MPLS Traffic Engineering (MPLS-TE) on Cisco IOS-XR. MPLS-TE is a technology that allows network operators to control the path that traffic takes through an MPLS network, optimizing bandwidth utilization and meeting service-level agreements. By entering this command, the user enters a configuration submode where global TE parameters can be set. This includes defining reoptimization timers, path selection preferences, and signaling protocols (RSVP-TE). On IOS-XR, MPLS-TE is tightly integrated with the underlying IGP (OSPF or ISIS) to distribute link attributes such as bandwidth, delay, and administrative groups. The command does not directly enable TE on interfaces; that requires separate interface-level configuration. MPLS-TE is essential for deploying traffic-engineered LSPs (TE tunnels) that can be used for bandwidth guarantees, fast reroute, and load balancing. In troubleshooting workflows, the 'mpls traffic-eng' command is the starting point for verifying global TE settings before diving into tunnel-specific issues. It is also used to configure features like auto-bandwidth, path protection, and logging of TE events. Understanding this command is fundamental for any network engineer working with MPLS-TE on IOS-XR platforms.

Syntax·Global Config

mpls traffic-eng

When to Use This Command

Configuring MPLS-TE tunnels for traffic engineering across a service provider backbone.
Setting up bandwidth reservations and explicit paths for latency-sensitive traffic.
Enabling fast reroute (FRR) protection for MPLS-TE tunnels.
Integrating MPLS-TE with ISIS or OSPF for link-state distribution of TE attributes.

Parameters

Parameter	Syntax	Required	Description
mpls traffic-eng	mpls traffic-eng	Required	This command has no parameters. It simply enters the MPLS-TE configuration submode. All subsequent TE-related global commands are issued under this submode.

Command Examples

Enter MPLS-TE Configuration Mode

mpls traffic-eng

RP/0/RP0/CPU0:router(config)# mpls traffic-eng
RP/0/RP0/CPU0:router(config-mpls-te)#

The prompt changes to (config-mpls-te)# indicating MPLS-TE configuration mode is active.

Configure MPLS-TE with ISIS

mpls traffic-eng
router isis 1
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0

RP/0/RP0/CPU0:router(config)# mpls traffic-eng
RP/0/RP0/CPU0:router(config-mpls-te)# exit
RP/0/RP0/CPU0:router(config)# router isis 1
RP/0/RP0/CPU0:router(config-isis)# mpls traffic-eng level-2-only
RP/0/RP0/CPU0:router(config-isis)# mpls traffic-eng router-id Loopback0

After entering MPLS-TE mode, the user exits and configures ISIS to distribute TE information. 'level-2-only' restricts TE to Level-2 only. 'router-id' sets the stable router ID for TE.

Understanding the Output

The command 'mpls traffic-eng' itself does not produce output; it changes the CLI prompt to indicate the user is in MPLS-TE configuration submode. The prompt changes from 'config' to 'config-mpls-te'. This submode allows configuration of global MPLS-TE parameters such as reoptimization timers, path selection, and signaling. To verify MPLS-TE configuration, use 'show mpls traffic-eng' commands. For example, 'show mpls traffic-eng tunnels' displays tunnel status, bandwidth, and path information. Key fields include: Tunnel Name, Status (up/down), LSP ID, Source/Destination, Bandwidth, and Path. Healthy values show 'up' status and bandwidth reservations matching configured values. Problem values include 'down' status, 'bandwidth not available', or path errors.

Configuration Scenarios

Basic MPLS-TE Configuration with ISIS

Service provider network using ISIS as IGP, need to enable MPLS-TE for tunnel deployment.

Topology

R1 --- R2 --- R3
Loopback0: 1.1.1.1, 2.2.2.2, 3.3.3.3

Steps

1.Enter global configuration mode.
2.Enter MPLS-TE submode with 'mpls traffic-eng'.
3.Configure global TE parameters (optional).
4.Exit to global config.
5.Configure ISIS to distribute TE information.
6.Enable MPLS-TE on interfaces.

Configuration

!
mpls traffic-eng
!
router isis 1
 net 49.0001.0000.0000.0001.00
 mpls traffic-eng level-2-only
 mpls traffic-eng router-id Loopback0
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.1.1.1 255.255.255.0
 mpls traffic-eng
!
interface Loopback0
 ipv4 address 1.1.1.1 255.255.255.255
!

Verify: Use 'show mpls traffic-eng tunnels summary' to verify TE is enabled. Use 'show isis mpls traffic-eng adjacency' to verify TE link information exchange.

Watch out: The 'mpls traffic-eng' command under the interface is required; without it, the interface cannot be used for TE tunnels even if the IGP is configured.

Troubleshooting with This Command

When troubleshooting MPLS-TE on IOS-XR, the 'mpls traffic-eng' command is the first step to ensure global TE configuration is present. If TE tunnels are not coming up, verify that the router is in MPLS-TE submode by checking the prompt. Common issues include missing 'mpls traffic-eng' under interfaces, incorrect IGP configuration, or mismatched TE parameters. Use 'show mpls traffic-eng tunnels' to check tunnel status; if tunnels are down, examine the path error using 'show mpls traffic-eng tunnels path' or 'show mpls traffic-eng link-management bandwidth'. Also, verify that RSVP is enabled (required for signaling) with 'show rsvp interface'. If the IGP is not distributing TE information, check 'show isis mpls traffic-eng adjacency' or 'show ospf mpls traffic-eng adjacency'. The 'mpls traffic-eng' submode also contains logging commands like 'logging events' to capture TE events for debugging. In IOS-XR, the configuration is committed with 'commit', so ensure changes are applied. For persistent issues, check the 'mpls traffic-eng reoptimize timers' and 'path-selection' settings. If tunnels are not using expected paths, verify explicit path definitions and administrative groups. The command 'show mpls traffic-eng topology' displays the TE topology database. Remember that on IOS-XR, the 'mpls traffic-eng' command is the foundation; without it, no TE configuration is possible.

CCNA Exam Tips

Remember that 'mpls traffic-eng' is a global configuration command that enters a submode; it does not enable TE on interfaces—that requires 'mpls traffic-eng' under the interface.

On IOS-XR, MPLS-TE is configured under the 'mpls traffic-eng' submode, not under 'router ospf' or 'router isis' directly; you must also enable TE under the IGP.

Know that the 'mpls traffic-eng router-id' command under the IGP is mandatory to set the TE router ID, typically a loopback interface.

Common Mistakes

Forgetting to enable MPLS-TE on interfaces with 'mpls traffic-eng' under the interface configuration; without this, TE tunnels cannot use the interface.

Not configuring the IGP (OSPF or ISIS) to distribute TE information; the IGP must have 'mpls traffic-eng' commands to advertise link attributes.

Using 'mpls traffic-eng' in global config but not entering the submode to configure parameters; the submode is required for most TE settings.

Platform Notes

On Cisco IOS-XR, the 'mpls traffic-eng' command behaves similarly to Cisco IOS but with important differences. In IOS-XR, the command enters a dedicated submode (config-mpls-te), whereas in classic IOS, TE parameters are often configured under the IGP or globally without a submode. IOS-XR requires explicit 'commit' to apply changes, unlike IOS where changes take effect immediately. The interface-level 'mpls traffic-eng' command is also required on IOS-XR, similar to IOS. However, IOS-XR uses a modular architecture; TE configuration is part of the MPLS package. For equivalent commands on other platforms, Juniper uses 'protocols mpls' and 'protocols rsvp' under 'edit'. On IOS-XR, RSVP is configured separately under 'rsvp' submode. Version differences: In IOS-XR 6.x and later, TE features like segment routing can coexist. Always check the specific version documentation. The 'mpls traffic-eng' command is available in all IOS-XR releases that support MPLS-TE.

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