L3 Router Configuration

Overview

NxtSight Networking supports two advanced router modes for production deployments: High Availability (HA) routers using VRRP for automatic failover between L3 agents, and Distributed Virtual Routing (DVR) that moves L3 forwarding to each compute node to eliminate centralized bottlenecks. This guide covers enabling and validating both modes.

Administrator Access Required — This operation requires the admin role. Contact your NxtSight administrator if you do not have sufficient permissions.

Prerequisites

Admin credentials sourced from openrc.sh
At least two L3 agents running for HA routers
nxtDeploy access to enable DVR cluster-wide

High-Availability Routers

HA routers use VRRP to provide automatic failover between L3 agent instances. When the active L3 agent fails, a standby agent takes ownership of the router’s namespace and floating IP NAT rules within seconds.

Create an HA Router

Authenticate

Source your credentials file to authenticate with the NxtSight platform:

Load credentials

source openrc.sh

Your administrator provides the RC (credentials) file for your project. See CLI Setup for configuration details.

Create HA router with external gateway

Create HA router

openstack router create ha-router \
  --ha \
  --external-gateway public

The --ha flag schedules the router across all available L3 agents automatically.

Verify HA state

Show HA router fields

openstack router show ha-router -f json | grep ha

Confirm ha: true and status: ACTIVE in the output.

List L3 agents handling the router

openstack network agent list --router ha-router

At least two L3 agents appear, one active and one standby.

HA routers require at least two L3 agents running in the cluster. NxtSight Networking automatically schedules the router across all available L3 agents. Verify with openstack network agent list --agent-type l3 before creating HA routers.

Distributed Virtual Routing (DVR)

DVR moves L3 forwarding from a centralized agent to each compute node, eliminating the network node as a bottleneck for east-west and north-south traffic.

Mode	Traffic Path	Best For
Centralized L3	All traffic through network node	Simple deployments, ≤ 10 compute nodes
DVR	East-west direct between compute nodes; north-south via dedicated gateway	High-throughput workloads, large clusters

Enable DVR

nxtDeploy

Enable DVR cluster-wide in nxtDeploy under Configuration → Networking:

Parameter	Value	Description
`neutron_l3_ha`	`True`	Enable VRRP HA for centralized L3 agents
`enable_neutron_dvr`	`True`	Distribute L3 forwarding to compute nodes

Click Save and Deploy. nxtDeploy applies the configuration via nxtVirt-ansible.

Enabling DVR on an existing cluster requires a rolling restart of all L3 and L2 agents. Plan a maintenance window and verify floating IP connectivity after the change. Test with a non-production network first.

Create a Distributed Router

Create distributed router

openstack router create distributed-router \
  --distributed \
  --external-gateway public

Verify distributed routing is enabled

openstack router show distributed-router -f json | grep distributed

Confirm distributed: true in the output.

Router Administration Reference

Operation	CLI Command
List all routers	`openstack router list`
Show router detail	`openstack router show <name>`
Enable router	`openstack router set <name> --enable`
Disable router	`openstack router set <name> --disable`
Set external gateway	`openstack router set <name> --external-gateway <network>`
Remove external gateway	`openstack router unset <name> --external-gateway`
Add subnet interface	`openstack router add subnet <router> <subnet>`
Remove subnet interface	`openstack router remove subnet <router> <subnet>`
Add static route	`openstack router set <name> --route destination=X,gateway=Y`
Delete router	`openstack router delete <name>`

Next Steps

Network Agent Management

Verify L3 agents are healthy across all network nodes

Provider Networks

Configure external networks that routers use as gateways

Routers and Gateways

User guide for creating and managing routers

Admin Troubleshooting

Diagnose HA router failover and DVR issues

Core Services

Other Services

L3 Router Configuration

Overview

High-Availability Routers

Create an HA Router

Authenticate

Create HA router with external gateway

Verify HA state

Distributed Virtual Routing (DVR)

Enable DVR

Create a Distributed Router

Router Administration Reference

Next Steps

Network Agent Management

Provider Networks

Routers and Gateways

Admin Troubleshooting

​Overview

​High-Availability Routers

​Create an HA Router

Authenticate

Create HA router with external gateway

Verify HA state

​Distributed Virtual Routing (DVR)

​Enable DVR

​Create a Distributed Router

​Router Administration Reference

​Next Steps

Network Agent Management

Provider Networks

Routers and Gateways

Admin Troubleshooting

Overview

High-Availability Routers

Create an HA Router

Distributed Virtual Routing (DVR)

Enable DVR

Create a Distributed Router

Router Administration Reference

Next Steps