Subnets Module¶

Overview¶

Service: OpenStack Neutron Identifier: subnets Version: 1.0.0 Location: /Sources/Substation/Modules/Subnets/

The Subnets module provides comprehensive subnet management capabilities including IPv4 and IPv6 subnet creation, CIDR network analysis, DHCP configuration, and router connectivity management. Subnets define IP address ranges within networks and control how IP addresses are allocated to ports. The module depends on the Networks module as subnets are always associated with a parent network.

Quick Reference¶

Feature	Supported	Details
List View	Yes	Full subnet listing with CIDR, gateway, and DHCP status
Detail View	Yes	Comprehensive subnet details with allocation pools and host routes
Create/Edit	Yes	Creation wizard with CIDR validation and DHCP configuration
Batch Operations	Yes	Bulk delete operations with confirmation
Multi-Select	Yes	Select multiple subnets for batch operations
Search/Filter	Yes	Filter by name, CIDR, network, or enable state
Auto-Refresh	Yes	60-second refresh interval with manual refresh option
Health Monitoring	Yes	Tracks IP allocation usage and DHCP agent status

Dependencies¶

Required Modules¶

networks - Required for parent network association and network lookups

Optional Modules¶

routers - Used for router interface attachment and gateway configuration

Features¶

Resource Management¶

Subnet Creation: Create IPv4 and IPv6 subnets with CIDR notation
IP Version Support: Full support for IPv4 and IPv6 addressing
DHCP Configuration: Enable/disable DHCP with options configuration
Allocation Pools: Define custom IP allocation ranges
Gateway Management: Configure gateway IP or disable gateway
DNS Configuration: Set DNS nameservers and domain name
Host Routes: Configure static routes for subnet routing
Router Attachment: Attach subnets to router interfaces
IP Allocation Tracking: Monitor IP usage and availability
Subnet Pools: Integration with subnet pool allocation

List Operations¶

The subnets list view provides a comprehensive overview of all subnets with CIDR information, DHCP status, and allocation statistics. The view supports filtering by parent network and IP version.

Available Actions:

Enter - View detailed subnet information
c - Create new subnet
d - Delete selected subnet
R - Manage router attachments
m - Toggle multi-select mode
M - Select all subnets
/ - Search subnets by name or CIDR
r - Refresh subnet list
q - Back to main menu

Detail View¶

The subnet detail view provides comprehensive information about IP allocation, DHCP configuration, and routing settings.

Displayed Information:

Basic Info: Name, ID, network ID, project
IP Configuration: CIDR, IP version, gateway IP
Allocation Pools: Start and end IP ranges for allocation
DHCP Settings: DHCP enabled status and options
DNS Configuration: Nameservers and DNS domain
Host Routes: Static routes with destination and nexthop
IP Usage: Total IPs, used IPs, available IPs
Router Interfaces: Attached router interfaces
Service Types: Network service types for subnet
Timestamps: Created and updated times

Create/Edit Operations¶

The subnet creation form provides comprehensive configuration for IP addressing and DHCP settings.

Form Fields:

Field	Type	Required	Description
Subnet Name	Text	No	Display name for the subnet
Network	Select	Yes	Parent network for the subnet
IP Version	Select	Yes	IPv4 or IPv6
CIDR	Text	Yes	Network address in CIDR notation
Gateway IP	Text	No	Gateway IP address (auto if blank)
No Gateway	Toggle	No	Disable gateway for isolated subnet
Enable DHCP	Toggle	Yes	Enable DHCP service (default: true)
Allocation Pools	List	No	Custom IP allocation ranges
DNS Nameservers	List	No	DNS server IP addresses
Host Routes	List	No	Static routes for the subnet
IPv6 Address Mode	Select	No	SLAAC, DHCPv6-stateful, DHCPv6-stateless
IPv6 RA Mode	Select	No	Router advertisement mode

Batch Operations¶

The Subnets module supports batch operations for managing multiple subnets efficiently.

Supported Batch Actions:

Bulk Delete: Delete multiple subnets with single confirmation
Bulk DHCP Toggle: Enable/disable DHCP on multiple subnets

API Endpoints¶

Primary Endpoints¶

GET /subnets - List all subnets with details
GET /subnets/{id} - Get detailed subnet information
POST /subnets - Create new subnet
PUT /subnets/{id} - Update subnet configuration
DELETE /subnets/{id} - Delete subnet

Secondary Endpoints¶

GET /networks/{id} - Get parent network information
PUT /routers/{id}/add_router_interface - Attach subnet to router
PUT /routers/{id}/remove_router_interface - Detach subnet from router
GET /ports?fixed_ips=subnet_id={id} - List ports using subnet

Configuration¶

Module Settings¶

// SubnetsModule Configuration
let subnetsConfig = SubnetsModuleConfig(
    identifier: "subnets",
    displayName: "Subnets (Neutron)",
    version: "1.0.0",
    dependencies: ["networks"],
    refreshInterval: 60.0,  // 60 seconds
    maxBulkOperations: 50,  // Maximum subnets for batch operations
    enableHealthChecks: true,
    defaultEnableDHCP: true,
    defaultIPVersion: 4
)

Environment Variables¶

NEUTRON_ENDPOINT - Neutron service endpoint URL (Default: from service catalog)
SUBNETS_REFRESH_INTERVAL - Refresh interval in seconds (Default: 60)
MAX_BULK_SUBNETS - Maximum subnets for batch operations (Default: 50)
DEFAULT_DNS_NAMESERVERS - Default DNS servers for new subnets (Default: 8.8.8.8,8.8.4.4)

Performance Tuning¶

Virtual Scrolling: Handles lists of 1,000+ subnets efficiently
Lazy Loading: Subnet details and allocation pools loaded on-demand
Batch Fetching: Fetches subnets in batches of 100
Cache TTL: 60-second cache with manual refresh option
IP Calculation Caching: CIDR calculations cached for performance

Views¶

Registered View Modes¶

Subnets List (`.subnets`)¶

Purpose: Display all subnets with CIDR information and management options

Key Features:

Virtual scrolling for large datasets
CIDR and gateway display
DHCP status indicators
IP allocation usage bars
Quick action buttons

Navigation:

Enter from: Main menu or Networks module
Exit to: Subnet detail, create form, or main menu

Subnet Detail (`.subnetDetail`)¶

Purpose: Display comprehensive subnet configuration and allocation details

Key Features:

Full IP configuration display
Allocation pool visualization
Host routes and DNS settings
Router interface information
IP usage statistics

Navigation:

Enter from: Subnets list
Exit to: Subnets list or router management

Subnet Create (`.subnetCreate`)¶

Purpose: Wizard for creating new subnets with validation

Key Features:

CIDR notation validation
Automatic gateway calculation
Allocation pool configuration
DHCP options setup
IPv6 configuration modes

Navigation:

Enter from: Subnets list via 'c' key
Exit to: Subnets list after creation

Router Management (`.subnetRouterManagement`)¶

Purpose: Manage subnet attachment to router interfaces

Key Features:

Available routers list
Current attachments display
Interface IP configuration
Attach/detach operations

Navigation:

Enter from: Subnets list via 'R' key
Exit to: Subnets list

Keyboard Shortcuts¶

Global Shortcuts (Available in all module views)¶

Key	Action	Context
`Enter`	Select/View Details	List views
`Esc`	Go Back	Any view
`q`	Quit to Main Menu	Any view
`/`	Search	List views
`r`	Refresh	List views

Module-Specific Shortcuts¶

Key	Action	View	Description
`c`	Create Subnet	List	Open subnet creation form
`d`	Delete Subnet	List	Delete selected subnet
`R`	Router Management	List	Manage router attachments
`D`	Toggle DHCP	List/Detail	Enable/disable DHCP service
`m`	Multi-Select	List	Toggle multi-select mode
`M`	Select All	List	Select all visible subnets
`A`	Add Allocation Pool	Create/Edit	Add IP allocation range
`N`	Add Nameserver	Create/Edit	Add DNS nameserver
`H`	Add Host Route	Create/Edit	Add static route

Data Provider¶

Provider Class: SubnetsDataProvider

Caching Strategy¶

The SubnetsDataProvider implements intelligent caching for subnet data and IP calculations. Subnet lists are cached for 60 seconds with automatic invalidation on modifications. CIDR calculations and IP usage statistics are cached separately.

Refresh Patterns¶

Periodic Refresh: Automatic refresh every 60 seconds
On-Demand Refresh: Manual refresh with 'r' key
Parent Network Sync: Refreshes when parent network changes
Router Interface Updates: Refreshes on attachment changes

Performance Optimizations¶

Virtual Scrolling: Renders only visible subnets
Lazy IP Calculation: IP statistics calculated on-demand
Batch API Calls: Groups multiple subnet fetches
CIDR Caching: Network calculations cached
Allocation Pool Optimization: Efficient range calculations

Known Limitations¶

Current Constraints¶

Subnet Pool Integration: Limited subnet pool allocation UI
Service Types: Cannot configure service types through UI
Segment Support: No support for network segment association
IPv6 Prefix Delegation: Not configurable in creation form
DHCP Options: Advanced DHCP options not exposed
Subnet Resize: Cannot modify CIDR after creation

Planned Improvements¶

Add subnet pool allocation interface
Implement service type configuration
Support network segment association
Add IPv6 prefix delegation options
Expose advanced DHCP configuration
Add subnet usage visualization graphs
Implement IP address calculator tool
Add subnet splitting/merging utilities

Examples¶

Common Usage Scenarios¶

Creating a Private Subnet¶

1. Press 'c' in subnets list
2. Select parent network (e.g., "private")
3. Enter subnet name (e.g., "private-subnet-10.0.1.0")
4. Select IP version (4)
5. Enter CIDR (e.g., "10.0.1.0/24")
6. Leave gateway blank for automatic assignment
7. Keep DHCP enabled
8. Add DNS nameservers (8.8.8.8, 8.8.4.4)
9. Press Enter to create

Attaching Subnet to Router¶

1. Select subnet in list view
2. Press 'R' for router management
3. Select target router from list
4. Optionally specify interface IP
5. Press Enter to attach
6. Verify in router interfaces view

Configuring Custom Allocation Pools¶

1. During subnet creation, press 'A'
2. Enter start IP (e.g., "10.0.1.100")
3. Enter end IP (e.g., "10.0.1.200")
4. Add additional pools as needed
5. Continue with subnet creation

Code Examples¶

Programmatic Access¶

// Access subnets through the module
let subnetsModule = tui.moduleRegistry.module(for: "subnets") as? SubnetsModule
let subnets = subnetsModule?.subnets ?? []

// Filter subnets by network
let networkSubnets = subnets.filter { $0.networkId == networkId }

// Calculate IP usage
let usage = subnet.calculateIPUsage()
print("Used: \(usage.used)/\(usage.total)")

Custom Integration¶

// Create subnet with custom configuration
extension SubnetsModule {
    func createSubnetWithPools(
        networkId: String,
        cidr: String,
        pools: [(String, String)]
    ) async throws {
        guard let tui = tui else { return }

        let allocationPools = pools.map {
            AllocationPool(start: $0.0, end: $0.1)
        }

        let subnet = Subnet(
            networkId: networkId,
            cidr: cidr,
            ipVersion: 4,
            enableDHCP: true,
            allocationPools: allocationPools
        )

        try await tui.client.createSubnet(subnet)
        await tui.dataManager.refreshSubnets()
    }
}

Troubleshooting¶

Common Issues¶

Subnet Creation Fails with Overlap Error¶

Symptoms: Creation fails with "overlapping CIDR" error Cause: CIDR range overlaps with existing subnet Solution: Check existing subnets, use non-overlapping CIDR

Cannot Delete Subnet¶

Symptoms: Delete fails with "subnet in use" error Cause: Subnet has active ports or router interface Solution: Delete ports and detach from router first

DHCP Not Working¶

Symptoms: Instances not receiving IP addresses Cause: DHCP agent down or network misconfiguration Solution: Check DHCP agent status, verify network configuration

IP Allocation Exhausted¶

Symptoms: Port creation fails with "no more IP addresses" Cause: All IPs in allocation pools used Solution: Expand allocation pools or create additional subnet

Debug Commands¶

openstack subnet show --debug {subnet-id} - Detailed subnet information
openstack port list --fixed-ip subnet={subnet-id} - List ports using subnet
neutron dhcp-agent-list-hosting-net {network-id} - Show DHCP agents
openstack subnet pool list - List available subnet pools

Module Metadata¶

Property	Value
Module Identifier	`subnets`
Display Name	Subnets (Neutron)
Version	1.0.0
Service	OpenStack Neutron
Category	Networking
Deletion Priority	4 (Medium-Low)
Load Order	21
Typical Memory Usage	5-15 MB
CPU Impact	Low

Last Updated: November 2024 Documentation Version: 1.0

Subnets Module¶

Overview¶

Quick Reference¶

Dependencies¶

Required Modules¶

Optional Modules¶

Features¶

Resource Management¶

List Operations¶

Detail View¶

Create/Edit Operations¶

Batch Operations¶

API Endpoints¶

Primary Endpoints¶

Secondary Endpoints¶

Configuration¶

Module Settings¶

Environment Variables¶

Performance Tuning¶

Views¶

Registered View Modes¶

Subnets List (.subnets)¶

Subnet Detail (.subnetDetail)¶

Subnet Create (.subnetCreate)¶

Router Management (.subnetRouterManagement)¶

Keyboard Shortcuts¶

Global Shortcuts (Available in all module views)¶

Module-Specific Shortcuts¶

Data Provider¶

Caching Strategy¶

Refresh Patterns¶

Performance Optimizations¶

Known Limitations¶

Current Constraints¶

Planned Improvements¶

Examples¶

Common Usage Scenarios¶

Creating a Private Subnet¶

Attaching Subnet to Router¶

Configuring Custom Allocation Pools¶

Code Examples¶

Programmatic Access¶

Custom Integration¶

Troubleshooting¶

Common Issues¶

Subnet Creation Fails with Overlap Error¶

Cannot Delete Subnet¶

DHCP Not Working¶

IP Allocation Exhausted¶

Debug Commands¶

Related Documentation¶

Module Metadata¶

Subnets List (`.subnets`)¶

Subnet Detail (`.subnetDetail`)¶

Subnet Create (`.subnetCreate`)¶

Router Management (`.subnetRouterManagement`)¶