---
title: "What is an xNIC?"
slug: "what-is-an-xnic"
updated: 2025-12-19T20:00:05Z
published: 2025-12-19T20:00:05Z
canonical: "docs.swxtch.io/what-is-an-xnic"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.swxtch.io/llms.txt
> Use this file to discover all available pages before exploring further.

# What is an xNIC?

> [!NOTE]
> WHAT TO EXPECT
> 
> In this article, users will learn how the xNIC, swXtch.io’s virtual NIC, fits into the cloudSwXtch infrastructure.

![cloudSwXtch Hybrid Network diagram xNIC](https://cdn.document360.io/84c5db44-f675-4f33-a980-5d3fc63073ca/Images/Documentation/cloudSwXtch%20Hybrid%20Network%20diagram%20xNIC.png)

## A Fully Virtualized NIC

The **xNIC** is a software service deployed by swXtch.io that creates a fully virtualized **Network Interface Controller (NIC)** within a virtual machine’s (VM) operating system. In tandem with the cloudSwXtch, the xNIC provides users with wXcked fast network connectivity and enables applications running on the VM to send and receive IP multicast traffic. It is seamless and transparent to all workloads, requiring no code changes.

xNIC installation for cloudSwXtch is required for multicast and broadcast to work across all major clouds — **AWS**, **Azure**, **GCP**, **OCI**, and even private clouds that lack multicast traffic. It is available on both [Linux](/v2/docs/install-xnic-on-linux) and [Windows](/v2/docs/install-xnic-windows) machines as well as [Kubernetes](/v2/docs/install-xnic-on-kubernetes). More details can be found in the [**xNIC system requirements**](/v2/docs/xnic-system-requirement) page.

In addition to multicast, the xNIC can perform high availability. At an endpoint, the xNIC compares packet reception from the multiple paths, detects dropped packets, and reconstructs the output stream in the correct order. For more information, see the [High Availability](/v2/docs/high-availability) page.

> [!WARNING]
> Q: Can xNIC work on any IP within the multicast address space?
> 
> A: We recommend referring to the IANA [IPv4 Multicast Address Space Registry](https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml). Currently, the xNIC can’t join a multicast stream if it’s on 224.0.0.1.

A software-based network switch with a virtual NIC service known as xNIC. Together these components create an overlay network on top of the standard cloud network. This overlay network adds many valuable network features, one of which is a seamless IP multicast experience.

This is the form of multicast that cloudSwXtch implements. It uses IP/UDP packets for transport and is described in detail in RFC 1112.