VS Virtual switches

In the context of computer networking and virtualization, a Virtual Switch (VS) is a software-based networking component that operates at the data link layer (Layer 2) of the OSI model. Virtual switches are commonly used in virtualized environments, such as data centers and cloud computing platforms, to enable communication between virtual machines (VMs) or containers running on a single physical host. They play a crucial role in managing network traffic within the virtualized environment and facilitating seamless communication between virtual instances.

Virtualization and the Need for Virtual Switches:

Virtualization allows multiple virtual instances (VMs or containers) to run on a single physical server or host. Each virtual instance behaves like an independent computing entity, running its operating system and applications. However, for these virtual instances to communicate with each other and with external networks, they require networking capabilities. This is where virtual switches come into play.

Functionality of Virtual Switches:

A Virtual Switch performs several key functions within a virtualized environment:

1. MAC Address Learning: Like physical switches, virtual switches use MAC address learning to build and maintain a MAC address table. This table maps MAC addresses of virtual instances to the corresponding virtual switch ports.
2. Forwarding: Virtual switches forward network traffic between virtual instances (VMs/containers) based on the destination MAC address in the MAC address table.
3. VLAN Tagging: Virtual switches can implement Virtual LAN (VLAN) tagging to segregate network traffic into separate broadcast domains. VLANs help improve network performance, security, and manageability.
4. Link Aggregation: Virtual switches can support link aggregation (also known as NIC teaming or bonding) to combine multiple physical network interfaces into a single logical interface. This provides higher bandwidth and redundancy.
5. Traffic Filtering and Access Control: Virtual switches can enforce traffic filtering and access control policies to ensure secure communication between virtual instances and to protect the virtualized environment from unauthorized access.
6. Integration with Physical Switches: Virtual switches can be integrated with physical switches in the network infrastructure, allowing seamless communication between virtual and physical devices.

Hypervisor Integration:

Virtual switches are an integral part of hypervisors, the software that enables virtualization on physical servers. Major hypervisors like VMware vSphere, Microsoft Hyper-V, and KVM (Kernel-based Virtual Machine) include built-in virtual switch functionality.

When a virtual machine is created, the hypervisor creates a corresponding virtual network interface card (vNIC) associated with a virtual switch port. The virtual switch then connects these vNICs to allow communication between virtual instances and with the physical network if required.

Types of Virtual Switches:

1. Distributed Virtual Switch (DVS): Some hypervisors, like VMware vSphere, offer a distributed virtual switch option. DVS extends virtual switch functionality across multiple physical hosts, allowing seamless VM migration and network policies across the data center.
2. Standard Virtual Switch: This is a basic virtual switch provided by most hypervisors, offering essential networking functions for communication between virtual instances and the external network.

Conclusion:

Virtual Switches (VS) play a critical role in virtualized environments, enabling communication between virtual machines and containers running on the same physical host. They provide essential networking functions such as MAC address learning, forwarding, VLAN tagging, and access control. Virtual switches are an integral part of hypervisors and facilitate the creation of highly scalable, flexible, and efficient virtualized network infrastructures in data centers, cloud computing platforms, and other virtualized environments.