Configuration Guide for Cisco NCS 1004, IOS XR Release 25.x.x

Configure the GCC0 interface on a QXP card

Updated: July 31, 2026

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Use this procedure to configure the GCC0 interface on a QXP card’s Coherent DSP controller by assigning it an IPv4 address for remote management when DCN access is unavailable

Use this task to enable and configure the GCC0 interface on a Coherent DSP controller in a QXP card. Assign an IPv4 address to the interface to facilitate configuration. The GCC0 interface operates at a data rate of 7.7 Mbps on the QXP card.

Table 1. Feature History
Feature Name	Release Information	Feature Description
GCC0 interface support on NCS1K4-QXP-K9 card	Cisco IOS XR Release 25.4.1	This feature introduces GCC0 interface support in Trunk OpenROADM mode for the DP04QSDD-HK9 pluggable on the NCS1K4-QXP-K9 card. The Coherent DSP controller supports the GCC0 interface, enabling you to remotely manage, monitor, and operate the chassis and line cards, especially in environments without direct Data Communication Network (DCN) access.

Follow these steps to configure the GCC0 interface on a QXP card.

Procedure

	1.	Enter configuration mode for the Coherent DSP controller and enable the GCC0 interface. Example: `RP/0/RP0/CPU0:ios#configure RP/0/RP0/CPU0:ios(config)#controller coherentDSP 0/0/0/0 RP/0/RP0/CPU0:ios(config-CoDSP)#gcc0 RP/0/RP0/CPU0:ios(config-CoDSP)#commit`
	2.	Enter the ipv4 address ipv4-address net-mask command to assign the IPv4 address and subset mask to the GCC0 interface. Example: `RP/0/RP0/CPU0:ios#configure RP/0/RP0/CPU0:ios(config)#interface gcc0 0/0/0/0 RP/0/RP0/CPU0:ios(config-CoDSP)#ipv4 address 192.0.2.1 255.255.255.0 RP/0/RP0/CPU0:ios(config-CoDSP)#commit`
	3.	(Optional) Enter the interface Loopback R/S/I/P ipv4 address ipv4-address command to configure the interface loopback. Example: `RP/0/RP0/CPU0:ios#configure RP/0/RP0/CPU0:ios(config)#interface Loopback0 RP/0/RP0/CPU0:ios(config-if)#ipv4 address 20.1.1.1 255.255.255.255`
	4.	(Optional) Enter the ipv4 unnumbered loopback 0 command to configure the GCC0 interface using the loopback IP address. Example: `RP/0/RP0/CPU0:ios#configure RP/0/RP0/CPU0:ios(config)#interface GCC0 0/1/0/0 RP/0/RP0/CPU0:ios(config-if)#ipv4 unnumbered loopback 0 RP/0/RP0/CPU0:ios(config-if)#exit RP/0/RP0/CPU0:ios(config)#exit`

The GCC0 interface is enabled with the specified IPv4 address and configured on the Coherent DSP controller of the QXP card.

Verify the GCC0 interface status and IPv4 configuration

Use this task to confirm the operational status and assigned IPv4 address of GCC0 interfaces.

Procedure

Run the show ipv4 interface brief command to display a summary of IPv4 interfaces.

Example:


RP/0/RP0/CPU0:ios#show ipv4 interface brief
Tue Sep 16 00:40:52.056 UTC
Interface                 IP-Address      Status          Protocol        Vrf-Name
GCC00/0/0/0               198.51.100.51     Up              Up              default
MgmtEth0/RP0/CPU0/0       192.0.2.32    Up              Up              default
MgmtEth0/RP0/CPU0/1       unassigned      Shutdown        Down            default
MgmtEth0/RP0/CPU0/2       unassigned      Shutdown        Down            default

The output displays the IPv4 address, status, and protocol for GCC0 interfaces, confirming their configuration.

Configure the MTU to prevent IP fragmentation on GCC0 for SCP

Use this task to prevent IP fragmentation on GCC0 interfaces during SCP protocol operations by limiting the maximum transmission unit (MTU).

IP fragmentation is not supported on GCC0 interfaces for the SCP protocol. To avoid fragmentation, configure the interface to restrict the maximum packet size to less than 1454 bytes, which is the fragmentation limit.

Procedure

	1.	Enter the configuration mode and enable the GCC0 interface. Example: `RP/0/RP0/CPU0:ios#configure RP/0/RP0/CPU0:ios(config)#interface gcc0 0/0/0/0`
	2.	Enter the command ipv4 mtu size to set the IPv4 MTU size for the GCC0 interface. The MTU size must be 1200 bytes. Example: `RP/0/RP0/CPU0:ios(config-if)#ipv4 mtu 1200 RP/0/RP0/CPU0:ios(config-if)#commit` The IPv4 MTU is now configured on the GCC0 interface. This setting limits the maximum packet size and prevents SCP-related fragmentation.

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