LVS介绍以及模式实现

一、LVS核心概念与架构

LVS(Linux Virtual Server)是由章文嵩博士开发的高性能负载均衡技术,通过内核层实现流量分发,提升并发处理能力与系统可用性。其核心组件包括:

Virtual Server (VS):调度器,负责接收客户端请求并转发至真实服务器(RS)。

Real Server (RS):实际处理请求的后端服务器。

VIP(Virtual IP):对外暴露的统一访问IP,隐藏后端RS的真实地址。

DIP(Director IP):VS内网接口IP,用于与RS通信。

RIP(Real Server IP):RS的公网/私网IP。

典型访问流程:

Client <--> VIP == DIP <--> RIP

客户端请求通过VIP到达VS,VS根据调度策略选择RS返回响应,最终数据包直接返回客户端1。

二、集群与分布式技术对比

LVS属于集群技术范畴,需与分布式技术区分:特性 集群 分布式

功能一致性 所有节点功能相同 节点分工协作

数据一致性 完全同步 按需拆分

扩展方式 向上扩展(Scale Up) 向外扩展(Scale Out)

容错机制 高可用(HA) 任务拆分冗余

SLA指标:MTBF(平均无故障时间) + MTTR(平均恢复时间) → A = MTBF / (MTBF + MTTR),目标达成率如99.9%1。

三、LVS工作模式解析

LVS支持四种转发模式,适用于不同网络拓扑:

NAT模式

特点:修改报文目标IP(DNAT),RS网关指向DIP。

优势:兼容性强,支持端口映射。

缺点:VS易成为瓶颈,需清理iptables规则1。

DR模式(直接路由)

特点:封装MAC首部,RS直接响应客户端。

优势:低延迟,适合跨网络场景。

NAT模式

VS主机

复制代码
[root@vsnode ~]# vmset.sh eth0 172.25.254.100 vsnode
[root@vsnode ~]# vmset.sh eth1 192.168.0.100 vsnode noroute

RS1

复制代码
[root@RS1 ~]# vmset.sh eth0 192.168.0.10 RS1 noroute
[root@RS1 ~]# nmcli connection modify eth0 ipv4.gateway 192.168.0.100
[root@RS1 ~]# nmcli connection reload
[root@RS1 ~]# nmcli connection up eth0
[root@RS1 ~]# route  -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.100   0.0.0.0         UG    100    0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.0   U     100    0        0 eth0


#设定访问业务真实数据
[root@RS1 ~]# dnf install httpd -y
[root@RS1 ~]# systemctl enable --now httpd
[root@RS1 ~]# echo RS1 - 192.168.0.10 > /var/www/html/index.html

RS2

复制代码
#设定网络
[root@RS1 ~]# vmset.sh eth0 192.168.0.20 RS1 noroute
[root@RS1 ~]# nmcli connection modify eth0 ipv4.gateway 192.168.0.100
[root@RS1 ~]# nmcli connection reload
[root@RS1 ~]# nmcli connection up eth0
[root@RS1 ~]# route  -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.100   0.0.0.0         UG    100    0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.0   U     100    0        0 eth0


#设定访问业务真实数据
[root@RS1 ~]# dnf install httpd -y
[root@RS1 ~]# systemctl enable --now httpd
[root@RS1 ~]# echo RS2 - 192.168.0.20 > /var/www/html/index.html

测试

复制代码
[root@vsnode ~]# curl  192.168.0.10
RS1 - 192.168.0.10
[root@vsnode ~]# curl  192.168.0.20
RS2 - 192.168.0.20

NAT模式实现

复制代码
#1,开启内核路由功能
[root@vsnode ~]# echo net.ipv4.ip_forward=1 >> /etc/sysctl.conf
[root@vsnode ~]# sysctl  -p
net.ipv4.ip_forward = 1

#2.编写策略
[root@vsnode ~]# ipvsadm -C
[root@vsnode ~]# ipvsadm -A -t 172.25.254.100:80 -s wrr
[root@vsnode ~]# ipvsadm -a -t 172.25.254.100:80 -r 192.168.0.10:80 -m  -w 1
[root@vsnode ~]# ipvsadm -a -t 172.25.254.100:80 -r 192.168.0.20:80 -m  -w 1
[root@vsnode ~]# ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.25.254.100:80 wrr
  -> 192.168.0.10:80              Masq    1      0          0
  -> 192.168.0.20:80              Masq    1      0          0


#测试
[root@vsnode ~]# for i in {1..10};do curl 172.25.254.100;done
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS2 - 192.168.0.20
RS1 - 192.168.0.10

更改权重接着测试

复制代码
#更改权重
[root@vsnode ~]# ipvsadm -e -t 172.25.254.100:80 -r 192.168.0.10:80 -m  -w 2
[root@vsnode ~]# ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.25.254.100:80 wrr
  -> 192.168.0.10:80              Masq    2      0          5
  -> 192.168.0.20:80              Masq    1      0          5
  
#测试
[root@vsnode ~]# for i in {1..10};do curl 172.25.254.100;done
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS1 - 192.168.0.10
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS1 - 192.168.0.10
RS2 - 192.168.0.20
RS1 - 192.168.0.10
RS1 - 192.168.0.10
RS2 - 192.168.0.20

DR模式实现

环境设定

复制代码
#在路由器中
[root@router ~]# systemctl disable --now ipvsadm.service
Removed "/etc/systemd/system/multi-user.target.wants/ipvsadm.service".
[root@router ~]# ipvsadm -C

#在路由器中
[root@router ~]# vmset.sh eth0 172.25.254.100 vsnode
[root@router ~]# vmset.sh eth1 192.168.0.100 vsnode noroute、

#设定内核路由功能
[root@router ~]# echo net.ipv4.ip_forward=1 >> /etc/sysctl.conf
[root@router ~]# sysctl  -p
net.ipv4.ip_forward = 1

#数据转发策略
[root@router ~]# iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source 192.168.0.100
[root@vsnode ~]# iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to-source 172.25.254.100

#vsnode 调度器
[root@vsnode ~]# vmset.sh  eth0 192.168.0.50 vsnode  norouter
[root@vsnode ~]# vim /etc/NetworkManager/system-connections/eth0.nmconnection
[connection]
id=eth0
type=ethernet
interface-name=eth0


[ipv4]
method=manual
address1==192.168.0.50/24,192.168.0.100

[root@vsnode ~]# cd  /etc/NetworkManager/system-connections/
[root@vsnode system-connections]#  cp -p eth0.nmconnection lo.nmconnection
[root@vsnode system-connections]# vim lo.nmconnection
[connection]
id=lo
type=loopback
interface-name=lo


[ipv4]
method=manual
address1==127.0.0.1/8
address2=192.168.0.200/32

[root@RS1 system-connections]# nmcli connection reload
[root@RS1 system-connections]# nmcli connection up eth0
连接已成功激活(D-Bus 活动路径:/org/freedesktop/NetworkManager/ActiveConnection/7)
[root@RS1 system-connections]# nmcli connection up  lo
连接已成功激活(D-Bus 活动路径:/org/freedesktop/NetworkManager/ActiveConnection/8)

#客户端
[root@client ~]# vmset.sh  eth0 172.25.254.99 client norouter
连接已成功激活(D-Bus 活动路径:/org/freedesktop/NetworkManager/ActiveConnection/4)
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:e5:75:af brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    altname ens160
    inet 172.25.254.99/24 brd 172.25.254.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fee5:75af/64 scope link tentative noprefixroute
       valid_lft forever preferred_lft forever
client

[root@client ~]# vim /etc/NetworkManager/system-connections/eth0.nmconnection
[connection]
id=eth0
type=ethernet
interface-name=eth0


[ipv4]
method=manual
address1=172.25.254.99/24,172.25.254.100
dns=8.8.8.8;

[root@client ~]# nmcli connection reload
[root@client ~]# nmcli connection up eth0
连接已成功激活(D-Bus 活动路径:/org/freedesktop/NetworkManager/ActiveConnection/5)
[root@client ~]# route  -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.25.254.100  0.0.0.0         UG    100    0        0 eth0
172.25.254.0    0.0.0.0         255.255.255.0   U     100    0        0 eth0

RS1

复制代码
#RS1
[root@RS1 ~]# vmset.sh eth0 192.168.0.10 RS1 noroute
[root@RS1 ~]# nmcli connection modify eth0 ipv4.gateway 192.168.0.100
[root@RS1 ~]# nmcli connection reload
[root@RS1 ~]# nmcli connection up eth0
[root@RS1 ~]# route  -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.100   0.0.0.0         UG    100    0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.0   U     100    0        0 eth0

#在lo上设定vip
[root@RS1 ~]# cd /etc/NetworkManager/system-connections/
[root@RS1 system-connections]# cp -p eth0.nmconnection lo.nmconnection
[root@RS1 system-connections]# vim lo.nmconnection
[connection]
id=lo
type=loopback
interface-name=lo

[ethernet]

[ipv4]
address1=127.0.0.1/8
address2=192.168.0.200/32
method=manual

[root@RS1 system-connections]# nmcli connection reload
[root@RS1 system-connections]# nmcli connection up lo
连接已成功激活(D-Bus 活动路径:/org/freedesktop/NetworkManager/ActiveConnection/6)
[root@RS1 system-connections]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet 192.168.0.200/32 scope global lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
       
 #arp禁止响应
[root@rs1 ~]# echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
[root@rs1 ~]# echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
[root@rs1 ~]# echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
[root@rs1 ~]# echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce

RS2

复制代码
#RS2
[root@RS2 ~]# vmset.sh eth0 192.168.0.20 RS2 noroute
[root@RS2 ~]# nmcli connection modify eth0 ipv4.gateway 192.168.0.100
[root@RS2 ~]# nmcli connection reload
[root@RS2 ~]# nmcli connection up eth0
[root@RS2 ~]# route  -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.0.100   0.0.0.0         UG    100    0        0 eth0
192.168.0.0     0.0.0.0         255.255.255.0   U     100    0        0 eth0

#在lo上设定vip
[root@RS2 ~]# cd /etc/NetworkManager/system-connections/
[root@RS2 system-connections]# cp -p eth0.nmconnection lo.nmconnection
[root@RS2 system-connections]# vim lo.nmconnection
[connection]
id=lo
type=loopback
interface-name=lo

[ethernet]

[ipv4]
address1=127.0.0.1/8
address2=192.168.0.200/32
method=manual

[root@RS2 system-connections]# nmcli connection reload
[root@RS2 system-connections]# nmcli connection up lo
连接已成功激活(D-Bus 活动路径:/org/freedesktop/NetworkManager/ActiveConnection/6)
[root@RS2 system-connections]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet 192.168.0.200/32 scope global lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
       
#arp禁止响应
[root@rs2 ~]# echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
[root@rs2 ~]# echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
[root@rs2 ~]# echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
[root@rs2 ~]# echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
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