Earlier, in a tutorial, I have discussed how to configure a Raspberry Pi as a Open Flow Switch. In this tutorial, I will show some basic bridge configuration in a Raspberry Pi open flow switch.
Open Flow Switch
OpenFlow is a communication protocol used to manage traffic between routers and switches in a Software-Defined Network (SDN). OpenFlow-based switches are the core of any SDN. In this tutorial, we’ll explore the basics of configuring a bridge using an OpenFlow switch.
An OpenFlow switch is a network device that uses the OpenFlow protocol to communicate with an OpenFlow controller. The controller provides the switch with a set of rules for forwarding packets, and the switch then follows those rules to make forwarding decisions.
OpenFlow switches allow network administrators to centralize network management and control traffic flows more dynamically.
Configure Open vSwitch by creating a bridge using the following command:
$ sudo ovs-vsctl add-br bridge_name
Replace “bridge_name” with the name you want to give your bridge.
Add your Raspberry Pi’s Ethernet interface to the bridge using the following command:
$ sudo ovs-vsctl add-port bridge_name eth0
Replace “bridge_name” with the name of your bridge and “eth0” with the name of your Ethernet interface.
To display the OpenFlow ports for the bridge, you can run the following command:
$ sudo ovs-ofctl show bridge_name
This command will output the OpenFlow ports for each physical port on the bridge, along with the port number assigned by OpenFlow. You can then use these port numbers in your OpenFlow rules.
Configure the IP address of your Raspberry Pi’s bridge interface:
$ sudo ifconfig bridge_name <IP_address> netmask <subnet_mask>
Replace “bridge_name” with the name of your bridge, and “
" and " " with your desired IP address and subnet mask.
or create a virtual interface using the following command
$ sudo ip addr add 192.168.1.1/24 dev mybridge
- Test your Open vSwitch configuration by pinging a device on your network from your Raspberry Pi.
Assign a name to the port that connects the two Raspberry Pi’s. You can use the following command to assign a name to the port:
$ sudo ovs-vsctl set interface <port_name> ofport_request=<port_number>
" with a name you want to assign to the port, and " " with a unique port number you want to assign to the port.
To deactivate the port, you can use the following command:
$ sudo ovs-ofctl mod-port bridge_name <port_name> down
Replace “bridge_name” with the name of the bridge that the port is attached to, and “
" with the name you assigned to the port in step 1.
To reactivate the port, you can use the following command:
$ sudo ovs-ofctl mod-port bridge_name <port_name> up
Adding Flow Rules
We can use the
ovs-ofctlcommand to add flow rules to the switch. The syntax for the command is as follows:
$ sudo ovs-ofctl add-flow <bridge> <flow>
<bridge>is the name of the OpenFlow switch, and
<flow>is the flow rule that you want to add.
Here is an example of a flow rule that forwards all incoming packets to port 2:
$ sudo ovs-ofctl add-flow br0 in_port=1,actions=output:2
This command adds a flow rule to the switch
br0that matches incoming packets on port 1 and forwards them to port 2.
We can also use the
ovs-appctlcommand to view the current flow rules on the switch:
$ sudo ovs-appctl ofproto/trace <bridge> <flow>
<bridge>is the name of the OpenFlow switch, and
<flow>is the flow rule that you want to trace. This command will display the flow of the packet through the switch and show which flow rules match the packet.
Troubleshooting- Check if a link is Active
You can check if an Ethernet cable is connected to one of the Ethernet ports on your Raspberry Pi using the
ethtool command. Here’s how you can do it:
ethtoolif it’s not already installed on your Raspberry Pi. You can use the following command to install it:
$ sudo apt-get install ethtool
Run the following command to check the link status of the Ethernet port:
$ sudo ethtool eth0
Replace “eth0” with the name of the Ethernet interface that you want to check.
The output of the command will show you the link status of the Ethernet port. If the cable is connected, the link status will be “Link detected: yes”. If the cable is not connected, the link status will be “Link detected: no”.
Here’s an example output of the command with a connected Ethernet cable:
Settings for eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised pause frame use: Symmetric Advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on MDI-X: off (auto) Supports Wake-on: pumbg Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes <-- Cable is connected
Here’s an example output of the command with a disconnected Ethernet cable:
Settings for eth0: Link detected: no <-- Cable is not connected
That’s all for today!!!
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- Build a Balena Cloud using Raspberry Pi
- How to Configure a Raspberry Pi as an OpenFlow Switch: Steps, Issues, and Solutions
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