# Prepare a RHEL Server

This article describes how prepare a RHEL Linux server to be added as a host to Platform9 Managed OpenStack (PMO).

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**Info**

For a description of PMO networking concepts, refer to the [Networking Basic Concepts tutorial](https://docs.platform9.com/managed-openstack/5.4/networks/networks-networking-concepts). Refer to [PMO prerequisites for Linux/KVM](https://docs.platform9.com/managed-openstack/5.4/getting-started/generic-linux-kvm-setup/getting-started-prerequisites-linux-kvm) for systems requirements and supported Ubuntu Operating System versions.
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### Supported Operating System Version

Platform9 Managed OpenStack supports RHEL versions 7.x and above.

### Step 1 - Install RHEL Operating System

Make sure that your server is configured appropriately with access to storage and physical networking. Download and install RHEL 7.6 on your physical server. You can download RHEL distributions from here: [RedHat Software](https://access.redhat.com/downloads)

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**IMPORTANT**

We recommend installing the minimal RHEL operating system. Platform9 agents are prepared to pull in any required package dependencies and get them installed on your server to prepare it to be part of OpenStack. This includes any libvirt/KVM package dependencies.
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It’s usually a good practice to get your system up to date with regard to the latest patches and updates.

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```bash
sudo yum -y update
```

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### Step 2 - Register the RHEL server and Subscribe to Red Hat Customer Portal

Run the following commands to register and attach the RHEL server to the Red Hat Customer Portal for updates, and enable the “server-optional” RPM repository.

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```bash
subscription-manager register
subscription-manager attach
subscription-manager repos —enable=rhel-7-server-optional-rpms
```

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### Step 3 - Ensure Virtualization is Enabled

Ensure that virtualization is enabled for your server by checking your server’s BIOS settings. If disabled, enable virtualization for the server to be able to act as a hypervisor within Platform9 Managed OpenStack.

### Step 4 - Install, Enable And Start the NTP Daemon.

This is required for all components to have their time synchronized.

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```bash
yum install -y ntp
systemctl enable ntpd
systemctl start ntpd
```

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### Step 5 - Configure Networking

PMO supports configuring your networking in two ways:

* Setup one or more dedicated networking servers to handle your networking.
* Setup Distributed Virtual Networking (DVR) and make each host a network host.

<figure><img src="https://1126553421-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FZ8EciOmTwpkZCkUOCYd9%2Fuploads%2Fgit-blob-81d2b9e2b382b810ef3e24f5b03b057dc5d766ce%2F1604970762.png?alt=media" alt="Figure 1.  Neutron Network Configuration Example"><figcaption><p>Figure 1. Neutron Network Configuration Example</p></figcaption></figure>

### Step 6 - Set SELinux to permissive

This is required for Open vSwitch (OVS) to be able to manage networking

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```bash
sed -i s/SELINUX=enforcing/SELINUX=permissive/g /etc/selinux/config
setenforce 0
```

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### Step 7 - Disable Firewalld and NetworkManager

This is required for KVM and OVS to be able to create iptables rules directly without Firewalld getting in the way.

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```bash
systemctl disable firewalld
systemctl stop firewalld
```

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```bash
systemctl disable NetworkManager
systemctl stop NetworkManager
```

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### Step 8 - Enable Network

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```bash
systemctl enable network
```

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### Step 9 - Load the modules needed for Neutron

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{% tab title="Bash" %}

```bash
modprobe bridge
modprobe 8021q
modprobe bonding
modprobe br_netfilter
echo bridge > /etc/modules-load.d/pf9.conf
echo 8021q >> /etc/modules-load.d/pf9.conf
echo bonding >> /etc/modules-load.d/pf9.conf
echo br_netfilter >> /etc/modules-load.d/pf9.conf
```

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### Step 10 - Add sysctl options

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```bash
echo net.ipv4.conf.all.rp_filter=0 >> /etc/sysctl.conf
echo net.ipv4.conf.default.rp_filter=0 >> /etc/sysctl.conf
echo net.bridge.bridge-nf-call-iptables=1 >> /etc/sysctl.conf
echo net.ipv4.ip_forward=1 >> /etc/sysctl.conf
echo net.ipv4.tcp_mtu_probing=2 >> /etc/sysctl.conf
sysctl -p
```

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### Step 11 - Add the Platform9 YUM Repo

Run the following command to install the Platform9 YUM repository.

For Platform9 releases up to and including 4.4:

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```bash
yum -y install https://s3-us-west-1.amazonaws.com/platform9-neutron/noarch/platform9-neutron-repo-1-0.noarch.rpm
```

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For Platform9 releases from 4.5 onwards:

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```bash
yum -y install https://s3-us-west-1.amazonaws.com/platform9-neutron/noarch/platform9-neutron-repo.noarch.rpm
```

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### Step 12 - Install Open vSwitch

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```bash
yum -y install --disablerepo="*" --enablerepo="platform9-neutron-repo" openvswitch
```

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### Step 13 - Enable and start Open vSwitch

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```bash
systemctl enable openvswitch
systemctl start openvswitch
```

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### Step 14 - Install QEMU KVM RHV

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```bash
yum install qemu-kvm-rhv
```

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### Step 15 - Install Router Advertisement Daemon

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```bash
yum -y install radvd
```

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### Step 16 - Configure physical interfaces

We are assuming eth0 and eth1. Please substitute your correct interface names. We are assuming an MTU of 9000 (VXLAN requires an MTU of at least 1600) Make sure all physical switches are configured to handle this MTU or you will have problems.

**/etc/sysconfig/network-scripts/ifcfg-eth0**

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```bash
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=none
MTU=9000
MASTER=bond0
SLAVE=yes
```

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**/etc/sysconfig/network-scripts/ifcfg-eth1**

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```bash
DEVICE=eth1
ONBOOT=yes
BOOTPROTO=none
MTU=9000
MASTER=bond0
SLAVE=yes
```

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### Step 17 - Setup the Bond interface

We are assuming bonding type=4 (LACP) refer to [Bonding Types](https://wiki.centos.org/TipsAndTricks/BondingInterfaces) to learn more.

**/etc/sysconfig/network-scripts/ifcfg-bond0**

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```bash
DEVICE=bond0
ONBOOT=yes
TYPE=OVSPort
DEVICETYPE=ovs
OVS_BRIDGE=br-vlan
BONDING_MASTER=yes
BONDING_OPTS="mode=4"
MTU=9000
```

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### Step 18 - Setup the VLAN trunk Bridge

**/etc/sysconfig/network-scripts/ifcfg-br-vlan**

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```bash
DEVICE=br-vlan
BOOTPROTO=none
ONBOOT=yes
TYPE=OVSBridge
DEVICETYPE=ovs
```

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### Step 19 - Setup the Management interface

We are assuming VLAN 101 for the Management network. Please use your correct VLAN ID for your environment. We are assuming subnet 192.0.2.0/24 for Management. Please use your correct subnet.

**/etc/sysconfig/network-scripts/ifcfg-bond0.101**

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```bash
DEVICE=bond0.101
ONBOOT=yes
BOOTPROTO=none
TYPE=Vlan
VLAN=yes
IPADDR=192.0.2.10
NETMASK=255.255.255.0
GATEWAY=192.0.2.1
DNS1=192.0.2.100
DNS2=192.0.2.200
```

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### Step 20 - Setup the VXLAN/GRE tunneling interface (Optional)

We are assuming VLAN 102 for VXLAN/GRE tunneling. Please use your correct VLAN We are assuming subnet 198.51.100.0/24 for VXLAN/GRE tunneling. Please use your correct subnet.

**/etc/sysconfig/network-scripts/ifcfg-bond0.102**

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{% tab title="Bash" %}

```bash
DEVICE=bond0.102
ONBOOT=yes
BOOTPROTO=none
TYPE=Vlan
VLAN=yes
IPADDR=198.51.100.10
NETMASK=255.255.255.0
```

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### Step 21 - Setup the External Interface and External Bridge

We are assuming VLAN 103 for the external network. Please use your correct VLAN.

**/etc/sysconfig/network-scripts/ifcfg-bond0.103**

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{% tab title="Bash" %}

```bash
DEVICE=bond0.104
ONBOOT=yes
BOOTPROTO=none
TYPE=Vlan
VLAN=yes
IPADDR=203.0.113.10
NETMASK=255.255.255.0
```

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**/etc/sysconfig/network-scripts/ifcfg-br-ext**

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```bash
DEVICE=bond0.104
ONBOOT=yes
BOOTPROTO=none
TYPE=Vlan
VLAN=yes
IPADDR=203.0.113.10
NETMASK=255.255.255.0
```

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### Step 22 - Setup the Storage interface (Optional)

We are assuming VLAN 104 for the storage network. Please use your correct VLAN. We are assuming subnet 203.0.113.0/24 for the storage network. Please use your correct subnet.

**/etc/sysconfig/network-scripts/ifcfg-bond0.104**

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{% tab title="Bash" %}

```bash
DEVICE=bond0.104
ONBOOT=yes
BOOTPROTO=none
TYPE=Vlan
VLAN=yes
IPADDR=203.0.113.10
NETMASK=255.255.255.0
```

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### Step 23 - Restart Networking

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**Warning**

Make sure you have console access to your host. You will be disconnected if the configuration is incorrect.
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```bash
systemctl restart network.service
```

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### Step 24 - Add tag to external bridge (to enable bridge monitoring)

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```bash
ovs-vsctl br-set-external-id br-ext bridge-id br-ext
```

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At this point, your RHEL server is ready to be prepared with rest of storage and networking pre-requisites to be added to Platform9 Managed OpenStack.