Error: NCM Webpages Time Out or Fail to Launch in DX NetOps

Products

• Network Observability

Issue/Introduction

NCM services start without error via systemctl, but web interfaces timeout and fail to launch during access attempts.​​​​​​​․

SYMPTOMS:

• systemctl status vcmaster shows services running without error.

• Web consoles time out and fail to load.

• Administrative interface freezes during device removal operations.

CONTEXT: Occurs in Test environments after server restarts at the VM level or following mass device import modifications.

 

Environment

• OS: RHEL 9.6

• Product Release: 25.4.1

Cause

ROOT CAUSE: The firewalld service was running on the RHEL 9.6 host and blocking network access to the NCM web application ports.

Resolution

PREREQUISITES:

• Root or Sudo access to the RHEL 9.6 terminal.

• Ability to manage system services (systemctl).

STEPS:

1. CHECK FIREWALL STATUS: Verify if the firewalld service is active and blocking application ports.

   Command: systemctl status firewalld

   EXPECTED: Service status is displayed.

2. DISABLE FIREWALL: Stop the firewalld service to restore application connectivity.

   Command: systemctl stop firewalld

   EXPECTED: Service stops and application webpages launch successfully. NOTE: If application access is restored, configure specific firewall rules to allow NCM traffic rather than leaving the firewall disabled.

VERIFY SUCCESS:

• Launch NCM web consoles.

• Confirm webpages load without timeout errors.

 

PREVENTION: Ensure firewall configurations persist across VM restarts or verify that necessary ports for DX NetOps NCM are whitelisted in the firewalld configuration.