In this project, we configure the OSPF dynamic routing protocol. The architecture of the network we are working with is descriped in this image:
For this project, we are not creating any Dockerfiles, images that already exist in docker hub are used. We are using the frr/frrouting (free range routing) image that will provides router containers. For PC terminals, an alpine image will be enough. So, be sure to pull both images before starting on the project.
To pull the images, run the following commands :
docker pull frrouting/frr
docker pull alpine
In the text file "Docker Commands.txt", there are all the commands used to create this project line by line. However, in the tutorial below, an explanation of these commands and steps is provided
First, we have to create the networks of the specified architecture. To create a network, run the following command in your terminal:
docker network create --driver=bridge --subnet=120.0.0.0/24 Network_name
We need to create 4 networks as specidied in the architecture.
Second, we have to create the ospf routers. To create a router, run the following command:
docker run -it -d --cap-add=NET_ADMIN --privileged --name Router_name --hostname Router_name --network Network_name --init frrouting/frr bash
We are going to need 4 routers. For routers 1, 2 and 3, we need to attach them to 2 networks. To do that, just add another --network tag and type the second network.
Third, We create the PC containers by running the following command:
docker run -it -d --cap-add=NET_ADMIN --privileged --name PC --hostname PC --network Network_name --init alpine sh
We need 7 PCs to follow the architecture. However, you can add just one PC per networks.
A very important step is to design the routers we created as default gateway. In docker, every container created has a default gateway with IP adress X.X.X.1/24. We need to change that to the IP adress of our routers. To do that, open a terminal of the container and run the following commands:
ip route del 0.0.0.0/0 via 120.0.1.1
ip route add 0.0.0.0/0 via 120.0.1.2
You can make sure that the default gateway is changed if you run:
ip address
Fourth, We are doing the most important part of the project : OSPF configuration. The free range routing image is a very complex images with a lot of functionalities. In dynamic routing, it has not only OSPF, bur RIP, BGP, EIRGP... We are going to focus just on the OSPF part. To configure OSPF, open a terminal of the router container and run the following commands :
bash
cd /usr/lib/frr
./watchfrr zebra ospfd &
vtysh
Zebra and ospfd daemons are activated. The actual configuration starts from here:
configure terminal
router ospf
network 120.0.0.0/24 area 0
exit
exit
This allows you to add an area. To follow the architecture, we need to do this configuration 4 times. One in each router. Note that in routers 1, 2, and 3, we need to add two areas : the backbone area 0, and the area that corresponds to the second network where the router is. To do that, just run the network command twice with necessary modifications.
Fifth and last, we need to test if our protocoe is running. First, we can check if the routes added are shown in the routing table. To do that, in the terminal of the router run the following commands (we should stay on the same directory):
vtysh
show ip route
This must show the OSPF routes (symbole O) if everything is done correclty.
And of course, we can ping the PCs to make sure packets are routed through the network. In a PC terminal (PC0 for example), run the following command:
ping <destination IP address of PC6>
To track the packets sent from PC0 to PC6, we can run the traceroute command (It should be installed first in the alpine container with apk add command):
traceroute <destination IP address of PC6>