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This article shows you how to understand Neutorn LBaaS, the content is concise and easy to understand, can definitely brighten your eyes, through the detailed introduction of this article, I hope you can gain something.

Load Balance as a Service (LBaaS) is an advanced network service provided by Neutron.

LBaaS allows tenants to create and manage load balancer in their own network.

Load balancer can be said to be a relatively basic component in a distributed system.

It receives the request from the front end, and then forwards the request to a processing unit in the back-end resource pool according to some balancing strategy to complete the processing.

Load balancer can achieve high availability and scale out of the system.

LBaaS has three main concepts: Pool Member,Pool and Virtual IP

Pool Member

Pool Member is an entity of layer 4 that has an IP address and provides services through a listening port.

For example, Pool Member could be a web server,IP of 172.16.100.9 and provide HTTP services over port 80.

Pool

Pool consists of a set of Pool Member. These Pool Member usually provide the same kind of service.

For example, a web server pool that contains: web1:172.16.100.9:80 web2:172.16.100.10:80

Virtual IP

Virtual IP, also known as VIP, is an IP address defined on load balancer.

Each pool member has its own IP, but the external service is through VIP.

Load balancer is responsible for listening for external connections and distributing them to pool member.

The external client only knows VIP and does not know or need to care about whether there is a pool or how many pool member there are.

OpenStack Neutron currently implements LBaaS by default through HAProxy software.

HAProxy is a popular open source load balancer.

Neutron also supports other third-party load balancer.

The following figure shows how HAProxy implements load balancer.

The figure on the left shows the data flow of client sending the request to web server:

1. Client 10.10.10.4 accesses the server's public network IP 10.10.10.7 through a browser.

two。 The request first arrives at the router and sets the destination address to the server's intranet VIP 172.16.100.11

3. VIP is set on load balancer. After receiving the request, load balancer selects pool member WEB1.

Set the destination IP of the packet to the address of WEB1 172.16.100.9.

4. Before forwarding the packet to WEB1, load balancer modifies the source IP of the packet to its own VIP address 172.16.100.11

The purpose is to ensure that WEB1 can send reply data back to load balancer.

5. WEB1 receives the request packet.

The figure shows the data flow of the web server reply:

1. WEB1 sends the packet to load balancer.

2. After load balancer receives the data sent back by WEB1, modify the destination IP to the address of Client 10.10.10.4. At the same time, the source IP of the packet is modified to the VIP address 172.16.100.11 to ensure that Client can send subsequent data to itself.

3. Load balancer sends the data to the router.

4. The router restores the original address of the packet to the server's extranet IP 10.10.10.7, and then sends it to Client.

5. Client receives the reply data.

That's how Load Balance as a Service works.

The above content is how to understand Neutorn LBaaS. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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