# Networking Integration With Flannel

## What is Flannel?

Flannel is a very simple overlay network that provides an easy way to configure a layer 3 network fabric designed for Kubernetes. Flannel runs a small, single binary agent called flanneld on each host, and is responsible for allocating a subnet lease to each host out of a larger, preconfigured address space. Flannel uses either the Kubernetes API or etcd directly to store the network configuration, the allocated subnets, and any auxiliary data (such as the host’s public IP). Packets are forwarded using one of several backend mechanisms including VXLAN and various cloud integrations.

For more information on Flannel, refer to [Project Flannel Github Page.](https://github.com/coreos/flannel/)

Flannel may be paired with several different backends. Platform9 Managed Kubernetes supports deploying Flannel with two backend options - using Flannel with UDP backend, or using Flannel with VXLAN backend and with Calico for network policies.

## Cloud Provider Support Matrix and Prerequisites

| Cloud provider      | Support for Flannel | Prerequisites                                                                                                                                                                                                               |
| ------------------- | ------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Bare Metal Provider | Yes                 | <p>- Follow the general purpose <a href="https://platform9.com/docs/bare-metal/networking-prerequisites">Networking Prerequisites</a>.<br>- Port 8285 must be open on all nodes of the cluster for UDP protocol.</p>        |
| AWS Provider        | Yes                 | None. All prerequisites are configured by the Managed Kubernetes AWS Provider.                                                                                                                                              |
| Azure Provider      | Yes                 | None. All prerequisites are configured by the Managed Kubernetes Azure Provider.                                                                                                                                            |
| OpenStack Provider  | Yes                 | <p>- Follow the general purpose <a href="https://platform9.com/docs/kubernetes/bareos-networking-prerequisites">Networking Prerequisites</a>.<br>- Port 8285 must be open on all nodes of the cluster for UDP protocol.</p> |
| VMware Provider     | Yes                 | <p>- Follow the general purpose<a href="https://platform9.com/docs/kubernetes/bareos-networking-prerequisites"> Networking Prerequisites</a>.<br>- Port 8285 must be open on all nodes of the cluster for UDP protocol.</p> |

## Create Cluster Using Flannel With UDP Backend

While creating the cluster, under Network Configuration, select Flannel as the network option.


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