Troubleshooting NSX Service Router High-Availability Issues

Products

• VMware NSX
• VMware Cloud Foundation

Issue/Introduction

This document provides guidance to troubleshoot VMware NSX Service-Router HA State is not Active nor Standby

Environment

VMware NSX-T DataCenter 3.x

VMware NSX 4.x

VCF 9.x

Resolution

Checking Service Router's High-Availability State

• Service Router (SR) High-Availability state can be queried from CLI:

nsxedge> get gateway 20ea2401-####-####-####-10226e7639f0 high-availability status
Service Gateway
UUID                  : 20ea2401-####-####-####-10226e7639f0
state                 : Down
down reason           : Node Down
type                  : TIER0
mode                  : A/S
failover mode         : Preemptive
rank                  : 0
service count         : 0
service score         : 0
HA ports state
    UUID        : 913254be-####-####-####-36df4bd76e8c
    op_state    : Down
    addresses   : 169.254.0.2/24;fe80::50:####:fe56:5300/64

• The state shows the current SR's HA state.
  • It should be either Active or Standby for Active/Standby mode SR (mode: A/S), and should be Active for Active/Active or Stateful Active/Active SR.
  • If the SR is not in Active/Standby state, or was not in Active/Standby state but recovered, HA history state CLI can be used to get the fail reason:

nsxedge> get gateway 20ea2401-####-####-####-10226e7639f0 high-availability history state details
State           : Init
Event           : Init
Reason          : Start
Resources       :
Time            : 2025-10-01T17:08:13.046985

State           : Down
Event           : Init
Reason          : Start
Resources       :
Time            : 2025-10-01T17:08:13.047018

State           : Standby
Event           : Node Up
Reason          : Bootup Precheck Passed
Resources       :
Time            : 2025-10-01T17:10:27.562288

State           : Active
Event           : Node Up
Reason          : Bootup Precheck Passed
Resources       : 0
Time            : 2025-10-01T17:10:27.562504

State           : Down
Event           : Node Down
Reason          : Device Down
Resources       :
Time            : 2025-10-01T17:25:34.403396

Service Router's High-Availability State Explained

Service Router's HA state can be in one of the following:

• Init:
  • The SR is just created. This is a transient state and should be move to next state right away.
• Down
  • The SR is down. Please check the next section for reasons that an SR can be down.
• Sync
  • The SR is syncing state with peers. Once the sync is completed, it will move to the next state.
• Standby
  • The SR is up and running and ready to take over as active. In Active/Standby mode, the SR can stay in Standby state if its peer is already in Active state. Otherwise, it will negotiate with its peer and move to Active if applicable.
• Active
  • The SR is up and running, and is actively forwarding packets and providing services.

Reasons for Service Router Down

• Node Down
  • The Edge node the SR is deployed is down. Please refer to KB Troubleshooting NSX Edge High-Availability Issues for Edge Node down troubleshooting
• Admin Down
  • The SR is put to down intentionally. This only happens during SR re-allocation before this SR is removed from the Edge and deployed on another Edge.
• Attached
  • The SR (VRF for example) is sharing fate with its master SR (default VR for example) and either the master SR is Down or the master SR has not been realized yet. Please check why the master SR is down.
• Detached
  • The SR stops sharing fate with its master SR and the SR itself is Down.
• Master State Update
  • The SR is sharing fate with its master SR and master SR is down. Please check the master SR high-availability status.
• Routing Down
  • Routing is down for this SR. Please refer to following KBs for routing down troubleshooting.
    • BGP session diagnostics for troubleshooting BGP session flaps on NSX-T edge node
    • Troubleshooting NSX BGP 
    • BFD session on the external interface is down alarm
    • BGP neighborship is down alarm
• All Uplink Devices Down
  • For T0 default vrf SR, if all its uplinks are connected to VLAN segment, and all the pnics for those VLAN segments are down, the SR will be down. Please refer to KB NSX Edge Upgrade Fails Due to PnicStatusInspectionTask for troubleshooting nic down issues.