Various network devices in OVS-5 minutes a day to play with OpenStack (128)

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In the previous section we enabled open VSwitch, this section will review the current network status and describe the various network devices involved in open VSwitch

Initial network status

Check the current network status.

Control Node

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The ifconfig display has three Bridges Br-ex,br-int and Br-tun on the control node.
From a naming perspective, we can roughly guess what they're used for:

Br-ex
Bridge connecting to an external (external) network

Br-int
Integrated (integration) bridge, all instance virtual network cards and other virtual networking devices are connected to the bridge.

Br-tun
Tunnel (tunnel) bridges, tunneling-based VxLAN and GRE networks will use the bridge for communication.

These bridges are automatically created for us by Neutron, but they are not visible through the Brctl show command.
This is because we are using open vSwitch instead of Linux Bridge and need to use the Open VSwitch command ovs-vsctl Show view as shown in:

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The output will be explained in detail later.

COMPUTE Nodes

There are also Br-int and Br-tun on the compute nodes, but no br-ext.
This is reasonable, because the traffic sent to the outside network is forwarded through the virtual router on the network node, so the Br-ext will only be placed on the network node (Devstack-controller).

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Understand the various network devices in the Open vSwitch environment

In an Open vSwitch environment, a packet sent from the instance to the physical NIC will roughly go through the following types of devices:

1. Tap interface is named Tapxxxx.

2. Linux Bridge is named Qbrxxxx.

3. Veth pair named Qvbxxxx, Qvoxxxx.

4. OVS Integration Bridge is named Br-int.

5. OVS patch ports is named Int-br-ethx and PHY-BR-ETHX (ordinal of Interface).

6. OVS provider Bridge is named Br-ethx (X is the ordinal of the interface).

7. The physical interface is named EthX (X is the ordinal of interface).

8. OVS Tunnel Bridge is named Br-tun.

OVS provider Bridge is used in flat and VLAN networks, and OVS Tunnel Bridge is used in Vxlan and GRE networks. These devices are discussed in detail later through an instance.

Open VSwitch supports all five network types for local, flat, VLAN, Vxlan and GRE.
Vxlan and GRE are very similar, next we will delve into how Open vSwitch implements local, flat, VLAN, and Vlxan.

The next section starts with the local network.

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Various network devices in OVS-play with OpenStack 5 minutes per day