Introduction

So I had this idea when looking at FRRouting. As it's a Linux package, you can install it on a box running KVM/Libvirt, then you can enable BGP and redistribute the connected networks. This makes spinning up new virtual networks on the hypervisor very easy as you do not need to rely on static routes and as soon as you spin up a new virtual network it's advertising to the rest of your network.

What is FRRouting (FRR)
FRRouting (FRR) is a fork of Quagga. It's used in Cumulus networks OS as the routing suite.

This guide is based on an install of CentOS 7.5.

Step 1 Install FRR

Install the latest FRR rpm from https://github.com/FRRouting/frr/releases.
yum install -y https://github.com/FRRouting/frr/releases/download/frr-5.0.1/frr-5.0.1-2018070501.el7.centos.x86_64.rpm

Edit the daemons file and change the routing protocols you want from no to yes (you must always enable zebra) in this case zebra and bgpd.
vi /etc/frr/daemons

zebra=yes
bgpd=yes

Start FRR and set to start on boot.
systemctl enable frr && systemctl start frr

Check status of FRR - should show as active (running).
systemctl status frr

Step 2 configure FRR and BGP

open the FRR shell by typing the command.
vtysh

Enter configuration mode.

conf t

This step is optional this command puts all the FRR configuration into one file.
service integrated-vtysh-config

Configure BGP on the KVM host.

I am configuring a route-map used to prevent some routes from being redistributed also will tag a BGP community for all the permitted routes you do not need to do this but it gives you more control and tagging the route helps with visibility.

ip prefix-list PL_BGP_DENY_CONNECTED seq 5 permit 10.25.10.0/24

route-map RM_BGP_REDISTRIBUTED_CONNECTED deny 10
match ip address prefix-list PL_BGP_DENY_CONNECTED

route-map RM_BGP_REDISTRIBUTED_CONNECTED permit 9999
set community 65010:10100

Here we are configuring the BGP process AS/router id/tuning the timers from the default to 2/6 and configuring the neighbour.

router bgp 65010
bgp router-id 10.25.10.100
bgp log-neighbor-changes
timers bgp 2 6
neighbor 10.25.10.1 remote-as 65000

Now to configure the redistribute connected command and set the route map we have created.

address-family ipv4 unicast
redistribute connected route-map RM_BGP_REDISTRIBUTED_CONNECTED
exit-address-family

Exit and save the configuration.

end

write

Step 3 Verify BGP is up and that we have routes

Here we can see that the BGP session is up.

Below we can see that have two connected virtual networks in BGP and are receiving a default route from the router we are connected to.

Introduction

This is part three of Building a Networking Virtual Lab. Vagrant can be used to build a virtual lab on top of KVM/Libvirt.

Step 1 Vagrant CentOS packages to install

Install the latest Vagrant rpm from https://releases.hashicorp.com/vagrant/.
yum install -y https://releases.hashicorp.com/vagrant/2.1.2/vagrant_2.1.2_x86_64.rpm

Install required packages for Vagrant.
yum install -y rubygem-nokogiri gcc ruby-devel zlib-devel libvirt-devel

Check Vagrant is installed.
vagrant --version

Step 2 Install Vagrant plugins

Install plugins for Vagrant.
vagrant plugin install vagrant-libvirt
vagrant plugin install vagrant-mutate

Step 3 Test Vagrant is working

Add a Vagrant box for testing.
vagrant box add centos/7 --provider=libvirt

Make a directory for testing Vagrant.
mkdir test
cd test/

Create new Vagrant file.
vagrant init centos/7

Bring the VM up
vagrant up

Check status is running.
vagrant status

ssh to test the Vagrant image is working.
vagrant ssh
exit

Destroy the Vagrant image after you have confirmed Vagrant is working.
vagrant destroy

Remove the test directory.
cd ..
rm -rf test

Step 4 Add other boxes to your Lab

You can add any image from the publicly Vagrant cloud to your lab. you can find them at the link below.
https://app.vagrantup.com/boxes/search

If you can't find an image on the Vagrant cloud you can also make your own images from VMs that you have created.

You should now have Vagrant running on KVM/Libvirt.

Links

Part1
Part2

Introduction

This is part two of Building a Networking Virtual Lab. VNC can be used to manage your Hypervisor via the Virtual Machine Manager GUI.

Step 1 Install VNC/XFCE CentOS packages

yum install epel-release –y
yum groupinstall xfce -y
yum install tigervnc-server -y
yum -y groupinstall X11 -y

Step 2 Setup VNC password for user

Login as your kvmuser. You can use any username for this.
su - kvmuser
Set a VNC password for your user.
vncserver
Exit to move back to the root user.
exit

Backup the xstatup file.
mv /home/kvmuser/.vnc/xstartup /home/kvmuser/.vnc/xstartup.org
create a new xstartup file.
vi /home/kvmuser/.vnc/xstartup

#!/bin/bash
xrdb $HOME/.Xresources
startxfce4 &

Fix owner/permissions on the new file.
chown kvmuser:kvmuser /home/kvmuser/.vnc/xstartup
chmod 755 /home/kvmuser/.vnc/xstartup

Copy the sample VNC service.
cp /lib/systemd/system/vncserver@.service /etc/systemd/system/vncserver@:1.service

Edit the following lines in the file to look like the below.
vi /etc/systemd/system/vncserver@:1.service

#User=<USER>
ExecStart=/sbin/runuser -l kvmuser -c "/usr/bin/vncserver %i"
PIDFile=/home/kvmuser/.vnc/%H%i.pid

Step 3 Start VNC server

Permit the VNC service on the firewall and reload the firewall service.
firewall-cmd --permanent --zone=public --add-service vnc-server
firewall-cmd --reload

As we have made changes to the systemctl we need to reload the daemon.
systemctl daemon-reload

Start the vncserver service and set to start at boot.
systemctl enable vncserver@:1 && systemctl start vncserver@:1

Step 4 Start vnc server

Connect to the hypervisor via VNC to use Virtial Machine Manager.

Links

Part1
Part3

Introduction

I have split this guide into three parts. Part one deals with installing KVM/Libvirt.
Part two installs VNC to connect to your remote host to use Virtual Machine Manager (VMM), Useful if you are accessing the hypervisor via a Windows or Mac computer, Linux has an installable version of VMM, making this step optional or you can manage KVM/libvirt using the CLI tool virsh. Part three deals with installing Vagrant, again this is an optional step as you can just spin up virtual devices and connect them together.

Vagrant is used to spin up a virtual environment using KVM in this instance as a Hypervisor. it can be very useful as you can build a lab that is the same as your prod network or a reproducible lab used for your studies that can easily be destroyed and rebuilt in minutes.

This guide is based on a clean install of CentOS 7.5.

Your machine must have a processor that can support the environment.

Step 1 KVM/Libvirt CentOS packages to install

Update all packages.
yum update -y

Install KVM/Libvirt packages.
yum install -y qemu-kvm qemu-img libvirt virt-install libvirt-python libguestfs libguestfs-tools virt-manager

Start KVM/Libvirt and set to start on boot.
systemctl enable libvirtd && systemctl start libvirtd

Check status of libvirtd - should show as active (running).
systemctl status libvirtd

Step 2 Create a bridge interface

A bridge interface is required for allowing VMs to access the network that the hypervisor is connected to.

Find your machines physical by running the command ip add.

Create your bridge interface file.
cd /etc/sysconfig/network-scripts/
vi ifcfg-br0

TYPE=Bridge
ONBOOT=yes
DEVICE=br0
BOOTPROTO=static
IPADDR=10.25.3.63
PREFIX=22
GATEWAY=10.25.0.1
DNS1=8.8.8.8

Add physical interface to bridge.
vi ifcfg-eth0

BRIDGE=br0

Restart the network service .
systemctl restart network

Verify br0 has the static IP address you have set.
ip add

Step 3 Optional useful utilities

Some useful packages to install.
yum install wget net-tools nano ntp

systemctl enable ntpd && systemctl start ntpd

Links

Part2
Part3