Load Balancer Models¶

Added in version 3.0.0

This section provides an overview of the data models included in Nautobot to describe load balancers. These models enable users to represent, manage, and track load balancing configurations in a vendor-neutral and infrastructure-aware manner.

Models include Virtual Servers, Load Balancer Pools, Load Balancer Pool Members, Health Check Monitors, and SSL Certificate Profiles. Several of these models integrate with other parts of Nautobot core, including IPAM (for VIPs and pool member IPs), DCIM (for device and chassis assignment), Cloud (for service mapping), and Tenancy (for tenant ownership).

The models were built with traditional enterprise vendor implementations in mind, such as F5, Citrix NetScaler, A10 Networks, VMware Avi Load Balancer, and Fortinet.

You are encouraged to leverage the load balancer feature guide for a practical approach at building the data model and configurations.

Order of Operations¶

When configuring objects with the Load Balancer data models, follow this recommended order (as outlined in the Quick Walkthrough):

Virtual Servers (link to VIPs and Pools)
Load Balancer Pool Members (assign them to Pools)
Load Balancer Pools
Certificate Profiles (if needed)
Health Check Monitors
IP Addresses

Tip

Your actual build out may require you to fill out some of the necessary relationships and prerequisites, however logically working top to bottom helps ensure you are only building what you require.

Models Overview¶

Model Name	Description
Virtual Server	Represents a front-end VIP and port combination that distributes traffic to a backend pool.
Load Balancer Pool	A group of backend servers (Pool Members) serving traffic for a Virtual Server.
Load Balancer Pool Member	An individual backend node within a Load Balancer Pool.
Certificate Profile	Stores metadata for SSL/TLS certificates used by Virtual Servers or Pool Members.
Health Check Monitor	Monitors the health of Pool Members and Pools to determine availability.

Entity Relationship Diagram¶

---
title: Load Balancer Entity Relationship Diagram
---
erDiagram
    "load_balancers.VirtualServer"[VirtualServer] {
        string name UK
        IPAddress vip FK
        int port
        choices protocol
        Prefix source_nat_pool FK
        choices source_nat_type
        choices load_balancer_type
        boolean enabled
        boolean ssl_offload
        Device device FK
        DeviceRedundancyGroup device_redundancy_group FK
        CloudService cloud_service FK
        VirtualChassis virtual_chassis FK
        Tenant tenant FK
        HealthCheckMonitor health_check_monitor FK
        CertificateProfile certificate_profiles FK
        LoadBalancerPool load_balancer_pool FK
    }

    "load_balancers.LoadBalancerPool"[LoadBalancerPool] {
        string name
        choices load_balancing_algorithm
        HealthCheckMonitor health_check_monitor FK
        Tenant tenant FK
    }

    "load_balancers.LoadBalancerPoolMember"[LoadBalancerPoolMember] {
        IPAddress ip_address FK, UK
        string label
        LoadBalancerPool load_balancer_pool FK
        Status status FK
        CertificateProfile certificate_profiles FK
        int port UK
        boolean ssl_offload
        HealthCheckMonitor health_check_monitor FK
        Tenant tenant FK
    }

    "load_balancers.HealthCheckMonitor"[HealthCheckMonitor] {
        string name
        int interval
        int retry
        int timeout
        int port
        choices health_check_type
        Tenant tenant FK
    }

    "load_balancers.CertificateProfile"[CertificateProfile] {
        string name UK
        choices certificate_type
        string certificate_file_path
        string chain_file_path
        string key_file_path
        datetime expiration_date
        string cipher
        Tenant tenant FK
    }

    "ipam.IPAddress"[IPAddress] {

    }

    "ipam.Prefix"[Prefix] {

    }

    "dcim.Device"[Device] {

    }

    "dcim.DeviceRedundancyGroup"[DeviceRedundancyGroup] {

    }

    "cloud.CloudService"[CloudService] {

    }

    "dcim.VirtualChassis"[VirtualChassis] {

    }

    "tenancy.Tenant"[Tenant] {

    }

    "load_balancers.VirtualServer" }o--|| "ipam.IPAddress" : "must have"
    "load_balancers.VirtualServer" }o--o| "ipam.Prefix" : has
    "load_balancers.VirtualServer" }o--o| "dcim.Device" : has
    "load_balancers.VirtualServer" }o--o| "dcim.DeviceRedundancyGroup" : has
    "load_balancers.VirtualServer" }o--o| "cloud.CloudService" : has
    "load_balancers.VirtualServer" }o--o| "dcim.VirtualChassis" : has
    "load_balancers.VirtualServer" }o--o| "tenancy.Tenant" : has
    "load_balancers.VirtualServer" }o--o| "load_balancers.HealthCheckMonitor" : "may have"
    "load_balancers.VirtualServer" }o--o{ "load_balancers.CertificateProfile" : "may have"
    "load_balancers.VirtualServer" }o--o| "load_balancers.LoadBalancerPool" : "may have"

    "load_balancers.LoadBalancerPool" }o--o| "load_balancers.HealthCheckMonitor" : "may have"
    "load_balancers.LoadBalancerPool" }o--o| "tenancy.Tenant" : has

    "load_balancers.LoadBalancerPoolMember" }o--|| "ipam.IPAddress" : "must have"
    "load_balancers.LoadBalancerPoolMember" }o--|| "load_balancers.LoadBalancerPool" : "must have"
    "load_balancers.LoadBalancerPoolMember" }o--o{ "load_balancers.CertificateProfile" : "may have"
    "load_balancers.LoadBalancerPoolMember" }o--o| "load_balancers.HealthCheckMonitor" : "may have"
    "load_balancers.LoadBalancerPoolMember" }o--o| "tenancy.Tenant" : has
    "load_balancers.HealthCheckMonitor" }o--o| "tenancy.Tenant" : has
    "load_balancers.CertificateProfile" }o--o| "tenancy.Tenant" : has

Practical Diagram¶

This diagram provides a basic but practical example of how the model is used.

LB Models

Vendor Data Mappings¶

This table will help you map to specific vendor terminology.

Nautobot Model	F5	Citrix NetScaler	A10 Networks	VMware Avi Load Balancer	Fortinet (FortiADC)
VirtualServer	Virtual Server	Virtual Server	Virtual Server	Virtual Service	Virtual Server
LoadBalancerPool	Pool	Service Group	Service Group / Pool	Pool	Server Pool
LoadBalancerPoolMember	Pool Member / Node	Service / Server	Server	Pool Member	Pool Member / Real Server
HealthCheckMonitor	Monitor	Monitor	Health Monitor	Health Monitor	Health Check
CertificateProfile	SSL Profile / Certificate	SSL Profile / Certificate	SSL Template / Cert	SSL Profile / Certificate	SSL Profile / Certificate

Additional details:

F5: "Pool Member" is a node+port; "Node" is just an IP. SSL Profiles are used for certificates.
Citrix NetScaler: "Service Group" is a group of "Services" (servers). SSL Profiles are also used.
A10 Networks: "Service Group" is a pool; "Server" is a backend. SSL Templates manage certificates.
VMware Avi Load Balancer: "Virtual Service" is the frontend; "Pool" is the backend group; "Pool Member" is a server. SSL Profiles are used.
Fortinet: "Virtual Server" is the frontend; "Server Pool" is the backend group; "Real Server" is a pool member. SSL Profiles are used.

Vendor-Specific Configuration with Custom Fields¶

If you need to store vendor-specific configuration elements — such as F5 iRules, persistence profiles, or application-layer settings — the recommended approach is to use Custom Fields:

Use a multi-select custom field to track named elements like iRules or HTTP profiles.
Use a JSON custom field to store unstructured vendor configuration snippets.
Custom Fields can be scoped to specific object types (e.g., only VirtualServer or LoadBalancerPoolMember) to reflect how your load balancer applies these settings.

This design gives you flexibility to tailor the data model to your environment without forcing unsupported abstractions across different load balancer vendors.

Questions to ask of the data model¶

Given the data model, what questions would a user ask?

Given a virtual server, I would like to know which certificates it is using
Given a virtual server, I would like to know which device it is on
Given a pool, I would like to know all the pool members
Given a pool, I would like to know all the virtual servers it is connected to
I would like to be able to understand what certificates are going to expire soon