Networking Overview
Vapor provides comprehensive tools to configure and manage host and virtual machine networking. Its networking model leverages standard Linux networking technologies and software-defined abstractions to deliver isolation, traffic control, and high throughput.
Networking Abstractions and Architectures
Vapor structures network connectivity using four core Layer-2 and Layer-3 abstractions:
1. Linux Bridges (Virtual Switches)
A Linux Bridge is a software-defined Layer-2 network switch running inside the host kernel. It acts as an aggregator, forwarding ethernet frames between attached virtual machine network interfaces (tap devices) and a physical host network interface (uplink NIC).
- Bridging places virtual machines directly on the same physical subnet as the host, allowing them to acquire IP addresses from the physical network's DHCP servers.
2. Network Bonds (Link Aggregation)
A Network Bond combines multiple physical network interfaces (NICs) into a single logical channel to achieve link redundancy and increased throughput.
- Failover Protection: In active-backup mode, if one physical connection fails, traffic automatically shifts to the secondary interface without session interruption.
- Load Balancing: Modes like LACP (802.3ad) balance traffic across multiple interfaces, scaling link bandwidth (e.g. bonding two 10Gbps interfaces to form a 20Gbps logical channel).
3. VLANs (Virtual Local Area Networks)
VLANs (IEEE 802.1Q) segment a single physical or bridged network into multiple isolated logical networks at Layer 2.
- VLAN Tagging: Packets originating from a VM or interface are tagged with a numeric VLAN ID (ranging from 1 to 4094). The switch or bridge routes this traffic exclusively to other interfaces configured with the matching VLAN tag. This enforces traffic isolation without requiring dedicated physical switches.
4. Open vSwitch (OVS)
Open vSwitch is an enterprise-grade, multilayer virtual switch designed to facilitate automated, software-defined networking (SDN) configurations.
- Compared to traditional Linux bridges, OVS supports complex programmatic flow rules, QinQ double tagging, Spanning Tree Protocol (STP), and tunneling overlays (VXLAN, GRE).
- Vapor supports creating OVS bridges, attaching internal/patch/bond ports, configuring fail-secure/standalone modes, and rendering live visual topologies of virtual network layouts.