volt-vmm/networking/README.md

Volt Unified Networking

Shared network infrastructure for Volt VMs and Voltainer containers.

Architecture

┌─────────────────────────────────────────────────────────────────────┐
│                        Host (systemd-networkd)                       │
│  ┌────────────────────────────────────────────────────────────────┐ │
│  │                      volt0 (bridge)                             │ │
│  │                      10.42.0.1/24                               │ │
│  │  ┌──────────────────────────────────────────────────────────┐  │ │
│  │  │  Address Pool: 10.42.0.2 - 10.42.0.254 (DHCP or static)  │  │ │
│  │  └──────────────────────────────────────────────────────────┘  │ │
│  └────┬──────────┬──────────┬──────────┬──────────┬─────────────┘ │
│       │          │          │          │          │               │
│  ┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐         │
│  │  tap0   ││  tap1   ││ veth1a  ││ veth2a  ││ macvtap │         │
│  │ (NovaVM)││ (NovaVM)││(Voltain)││(Voltain)││ (pass)  │         │
│  └────┬────┘└────┬────┘└────┬────┘└────┬────┘└────┬────┘         │
│       │          │          │          │          │               │
└───────┼──────────┼──────────┼──────────┼──────────┼───────────────┘
        │          │          │          │          │
   ┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐     │
   │  VM 1   ││  VM 2   ││Container││Container│     │
   │10.42.0.2││10.42.0.3││10.42.0.4││10.42.0.5│     │
   └─────────┘└─────────┘└─────────┘└─────────┘     │
                                                    │
                                              ┌─────┴─────┐
                                              │ SR-IOV VF │
                                              │ Passthru  │
                                              └───────────┘

Network Types

1. Bridged (Default)

• VMs connect via TAP devices
• Containers connect via veth pairs
• All on same L2 network
• Full inter-VM and container communication

2. Isolated

• Per-workload network namespace
• No external connectivity
• Useful for security sandboxing

3. Host-Only

• NAT to host network
• No external inbound (unless port-mapped)
• iptables masquerade

4. Macvtap/SR-IOV

• Near-native network performance
• Direct physical NIC access
• For high-throughput workloads

Components

networking/
├── systemd/              # networkd unit files
│   ├── volt0.netdev      # Bridge device
│   ├── volt0.network     # Bridge network config
│   └── 90-volt-vmm.link # Link settings
├── pkg/                  # Go package
│   └── unified/          # Shared network management
├── configs/              # Example configurations
└── README.md

Usage

Installing systemd units

sudo cp systemd/*.netdev systemd/*.network /etc/systemd/network/
sudo systemctl restart systemd-networkd

Creating a TAP for Volt VM

import "volt-vmm/networking/pkg/unified"

nm := unified.NewManager("/run/volt-vmm/network")
tap, err := nm.CreateTAP("volt0", "vm-abc123")
// tap.Name = "tap-abc123"
// tap.FD = ready-to-use file descriptor

Creating veth for Voltainer container

veth, err := nm.CreateVeth("volt0", "container-xyz")
// veth.HostEnd = "veth-xyz-h" (in bridge)
// veth.ContainerEnd = "veth-xyz-c" (move to namespace)

IP Address Management (IPAM)

The unified IPAM provides:

• Static allocation from config
• Dynamic allocation from pool
• DHCP server integration (optional)
• Lease persistence

{
  "network": "volt0",
  "subnet": "10.42.0.0/24",
  "gateway": "10.42.0.1",
  "pool": {
    "start": "10.42.0.2",
    "end": "10.42.0.254"
  },
  "reservations": {
    "vm-web": "10.42.0.10",
    "container-db": "10.42.0.20"
  }
}