Load balancing in the NAT mode of LVS

Nat mode of LVS cluster

Basic concepts:

Cluster :cluster is a group of computers that provide users with a set of network resources as a whole, and these individual computer systems are nodes of the cluster

Types of clusters:

LB Load Balancer cluster HA high availability cluster HPC high Performance computing cluster

How LB is implemented:

1 Software-f5 Load Balancer

2 hardware LVS (4 layers) Nginx (7 layers)

LVS (Linux Virtual Server)

Official website: http://www.linuxvirtualserver.org (English)

http://zh.linuxvirtualserver.org

LVS mode

1 NAT 2 DR 3 TUN

The LVS cluster uses a three-tier structure:

1 Load Scheduler: Responsible for sending the customer's request to the real server execution, the customer will be considered to be the same IP address, we call the VIP address of the public network

2 Server pool: The server that really provides service to the user, the execution service has web,mail,ftp,dns and so on

3 shared storage: In order to ensure that the data provided by the server is consistent, the shared storage area provides the same service, the same content

Features of NAT

Pros: can support any operating system, as well as private networks, and only need a public IP address

Disadvantage: The performance of the entire system is limited, because the execution of NAT every time the need to rewrite the packet, there is a certain delay, another 80% of the data is sent from the server to the client, that is, the user's request is very short, and the server response is very large, the load Balancer to form a great pressure, become a new bottleneck

How the LVS NAT mode works

When the client accesses the scheduler, the scheduler rewrites the destination address of the request message through the network address translation, dispatches the request to the real server in the backend according to the preset scheduling algorithm, and the response message of the real server is rewritten by the scheduling algorithm, the source address of the message is overwritten, and then returned to the customer to complete the whole load dispatch process.

the dispenser is set Reset:

1 ability to turn on packet forwarding

vim/etc/sysctl.conf Net.ipv4.ip_forward = 1 sysctl-p effective immediately (power on automatically)

or modify the kernel parameters echo 1 > Proc/sys/net/ipv4/ip_forward (Temporary effect)

2 Installing the LVS management tool ipvsadmin

rpm-ivh/mnt/packages/ipvsadmin-1.25-9el6x86_64.rpm

3 Add IP address ifconfig-a to see all of the interface information

Setup adds an IP address to the same network segment as the real server

Restart Network Service: Service network restart

View the default gateway Route-n

4 Setting up Rules

Ipvsadm-a-T 192.168.1.63:80-s RR (start polling scheduling algorithm) (VIP)

-a means adding

-T represents the TCP service Vip:port

-s set scheduling algorithm RR indicates polling

5 Add Realserver Address

Ipvsadm-a-T 192.168.1.63:80-r 192.168.2.62-m

Ipvsadm-a-T 192.168.1.63:80-r 192.168.2.64-m

-a means to add an realserver address

-R Make Realserver address

-M means Masquerade is the LVs of NAT

6 Save Configuration

/etc/init.d/ipvsadm Save

7 Viewing Ipvsadmin rules

Ipvsadm-l-N

Ipvsadm-l-n-c (see details of connections)

-NL viewing rules, displaying the kernel Virtual server table

-NLC viewing the client connection dispatcher and Realserver

--state view distribution, number of databases and connections

--rate Viewing connection Rates

Configuration of multiple real server side:

1 Configuring the IP address

Vim/etc/sysconfig/network-scripts/ifcfg-eth0

2 Modifying the NIC mode

Modify the NIC mode to the same network segment as the dispatcher Vmnet4 communication is normal at the same address segment

3 Opening httpd Service

Download Web server software to open the httpd process

Yum Install-y httpd

Service httpd Restart

You can achieve NAT load balancing by writing a static page to the/var/www/html, as for the same storage pool, and I would like to write about it later.

This article is from the "Linux niche" blog, make sure to keep this source http://wangwenxi.blog.51cto.com/10480746/1685100

Load balancing in the NAT mode of LVS