Network Down Extern (P1 Critical Alert) - Troubleshooting Guide

KB 905833 - Network Down Extern (P1 Critical Alert) - Troubleshooting Guide

Purpose

This document provides a standardized approach for handling and troubleshooting the Network Down - Extern alert, including L1 and L2 actions, escalation procedures, and resolution criteria for critical incidents.

Alert Name

Network Down - Extern

Alert Description

This alert is triggered when the external network interface on a node is down or unavailable.

This interface is critical for:
  1. External communication and access
  2. User/application connectivity
  3. Cluster interaction with external systems
  4. Failure of this interface can isolate nodes from users, external services, and partially from cluster operations.

Severity

P1 – Critical Impact

Possible Causes

  1. Faulty or disconnected network cable
  2. SFP/transceiver issue
  3. Switch port failure or shutdown
  4. Gateway or network path unreachable
  5. Network service failure on server
  6. NIC hardware issue

L1 Engineer Actions

Step 1 – Log the Alert

Log the alert in the monitoring tool. Capture the parameters as below:
  1. Alert name
  2. Node/interface details
  3. Timestamp
  4. Current status

Step 2 – Create Ticket

  1. Monitor the alert for 15 minutes
  2. If the alert persists:
    1. Create an internal ticket
    2. Include all captured details

Step 3 – Escalation (If required)

  1. Inform L2 engineer immediately (P1 priority)
  2. Share complete alert information

Step 4 – Documentation

After confirmation with L2, update the Issue Master Sheet/ Issue Tracking Sheet.

L2 Engineer Actions

Step 1 – Network Reachability

  1. Ping the default gateway from the affected node
  2. Identify packet loss or connectivity failure

Step 2 – Interface & Link Status

  1. Check NIC/interface status (UP/DOWN)
  2. Review for errors and packet drops.

Step 3 – Switch-Level Checks

  1. Verify switch port status
  2. Analyze switch logs for:
    1. Link flaps
    2. Errors
    3. Port shutdown events

Step 4 – Physical Layer Validation

  1. Verify cable connections
  2. Check SFP/transceiver health
  3. Replace faulty components if required

Step 5 – Network Service Validation

  1. Restart network service on the affected node
  2. Recheck connectivity after restart

Step 6 – OEM Escalation (If required)

  1. If issue persists:
    1. Raise a case with OEM/vendor
    2. Share logs, actions performed, and timestamps

Resolution

The issue is considered resolved when:
  1. External interface status is UP
  2. Node is reachable externally
  3. No packet loss is observed
  4. Alert is cleared in the monitoring system

Escalation Matrix

Level

Responsibility

L1

Monitoring & logging

L2

Troubleshooting & resolution

OEM/Vendor

Advanced/network or hardware issues


  • L1 → L2: Immediate escalation for P1 alerts
  • L2 → OEM/Vendor: If issue persists after troubleshooting