Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

Configure SR-MPLS global block (GB)

Updated: April 17, 2026

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Configure SR-MPLS global block (GB) if you have an SR network between the border leaf switch in the ACI fabric and the DC-PE.

Configure the SR-MPLS global block to define the label range for segment routing in MPLS networks.

Configure SR-MPLS global block (GB) if you have an SR network between the border leaf switch in the ACI fabric and the DC-PE, as shown in the following figure.

We recommend that all nodes in an SR domain have the same SR-GB configuration.

Following are important guidelines to consider when configuring SR-MPLS global block:

The allowed configurable SR-GB range is 16000-471804.
The default SR-GB range in the ACI fabric is 16000-23999.
ACI always advertises implicit null for the underlay label (transport loopback).

Procedure

	1.	Navigate to the SR-MPLS Global Configurations window. Tenants > infra > Policies > Protocol > MPLS Global Configurations
	2.	Access the default MPLS Global Configurations screen by double-clicking on default in the main SR-MPLS Global Configurations screen or by clicking on default in the left nav bar, under MPLS Global Configurations. The default SR-MPLS Global Configurations window appears.
	3.	In the SR Global Block Minimum field, enter the minimum value for the SR-GB range. The lowest allowable value in this field is 16000.
	4.	In the SR Global Block Maximum field, enter the maximum value for the SR-GB range. The highest allowable value in this field is 471804.
	5.	Click Submit.

The SR-MPLS global block is configured with the specified label range, enabling segment routing functionality within the defined parameters.

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