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What is the basic concept of Neutron network? aiming at this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

Today we learn several important concepts of the Neutron module.

The network resources managed by Neutron include Network,subnet and port, which are described in turn below.

Network

Network is an isolated layer 2 broadcast domain. Neutron supports many types of network, including local, flat, VLAN, VxLAN and GRE.

Local

Local networks are isolated from other networks and nodes. Instance in local network can only communicate with instance in the same network on the same node, and local network is mainly used for stand-alone testing.

Flat

A flat network is a network without vlan tagging. Instance in a flat network can communicate with instance on the same network and can span multiple nodes.

Vlan

A vlan network is a network with 802.1q tagging. Vlan is a two-layer broadcast domain. Instance in the same vlan can communicate, while different vlan can only communicate through router. Vlan network, which can span nodes, is the most widely used network type.

Vxlan

Vxlan is an overlay network based on tunnel technology. Vxlan networks are distinguished from other vxlan networks by a unique segmentation ID, also known as VNI. Packets in vxlan are encapsulated into UPD packets for transmission through VNI. Because layer 2 packets are encapsulated and transmitted in layer 3, they can overcome the limitations of vlan and physical network infrastructure.

Gre

Gre is a kind of overlay network similar to vxlan. The main difference is that it is encapsulated using IP packages instead of UDP.

Different network are isolated on the second layer.

In vlan networks, for example, network An and network B assign different VLAN ID, which ensures that broadcast packets in network A do not go to network B. Of course, the isolation here refers to the isolation on the second layer, and it is possible to communicate on the third layer with the help of different network of the router.

Network must belong to a Project (Tenant tenant), and multiple network can be created in Project. The relationship between network and Project is one-to-many.

Subnet

Subnet is an IPv4 or IPv6 address field. The IP of the instance is allocated from the subnet. Each subnet needs to define the range and mask of the IP address.

Subnet and network have an one-to-many relationship. A subnet can only belong to a network;. A network can have multiple subnet. These subnet can be different IP segments, but cannot overlap. The following configuration is valid:

Network A subnet Amura: 10.10.1.0 end 24 {"start": "10.10.1.1", "end": "10.10.1.50"} subnet Amurb: 10.10.2.0 Universe 24 {"start": "10.10.2.1", "end": "10.10.2.50"}

But the following configuration is invalid because the subnet overlaps

NetworkA subnet Amura: 10.10.1.0 end 24 {"start": "10.10.1.1", "end": "10.10.1.50"} subnet Amurb: 10.10.1.0 amp 24 {"start": "10.10.1.51", "end": "10.10.1.100"}

This is not to determine whether the IP overlaps, but the CIDR overlaps of the subnet (all 10.10.1.0 Universe 24)

However, if subnet is in different network, both CIDR and IP can overlap, such as

Network A subnet Amura: 10.10.1.0 end 24 {"start": "10.10.1.1", "end": "10.10.1.50"} networkB subnet Bmura: 10.10.1.0 amp 24 {"start": "10.10.1.1", "end": "10.10.1.50"}

Here you can't help but wonder: if the above IP addresses can overlap, then there may be two instance with the same IP, will there be a conflict? The simple answer is: no!

Specific reason: because the router of Neutron is implemented through Linux network namespace. Network namespace is a network isolation mechanism. Through it, each router has its own independent routing table.

The above configuration has two results:

If two subnet are routed through the same router, only one specified subnet can be routed according to the configuration of the router.

If the two subnet above are routed through different router, both subnet can be routed because the routing table of the router is independent.

This is just a brief explanation, and we will analyze this scenario in detail in the next chapter of layer 3 routing.

Port

Port can be thought of as a port on a virtual switch. MAC address and IP address are defined on port, and when instance's virtual network card VIF (Virtual Interface) is bound to port, port assigns MAC and IP to VIF.

Port and subnet have an one-to-many relationship. A port must belong to a subnet;. A subnet can have multiple port.

The relationship between Project,Network,Subnet,Port and VIF is summarized below.

Project 1: m Network 1: m Subnet 1: m Port 1: 1 VIF m: 1 Instance

This is the answer to the question about what is the basic concept of Neutron network. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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