DHCP Principle and configuration

1.DHCP summary

DHCP(Dynamic Host Configuration Protocol, Dynamic Host Configuration Protocol ）

from Internet Designed and developed by the task force

Used exclusively for TCP/IP Computers in the network automatically assign TCP/IP Protocol of parameters

2. Use DHCP The benefits of

Reduce the workload of Administrators

Avoid the possibility of input errors

avoid IP Address conflict

When changed IP Address segment , There is no need to reconfigure each user's IP Address

Improved IP Address utilization

Facilitate client configuration

3.DHCP The way of distribution

Automatically assigned ： Assigned to a IP Permanent use after address

Manually assign ： from DHCP The server administrator specifically specifies IP Address

Dynamic allocation ： Release the after use IP, For other clients

4.DHCP Lease process

Client from DHCP Server get IP The process of addressing is called DHCP Lease process

There are four steps ：

5. Use DHCP Dynamically configure the host address

■ DHCP service

● Automatically assign addresses to a large number of clients , Provide centralized management

● Reduce management and maintenance costs 、 Improve network configuration efficiency

■ The assignable address information mainly includes

● NIC IP Address 、 Subnet mask

● Corresponding network address 、 Broadcast address

● Default gateway address

● DNS Server address

6. To configure

[[email protected] ~]# yum install -y dhcp

 install DHCP service 

[[email protected] ~]# cp /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example /etc/dhcp/dhcpd.conf

 Copy a more detailed configuration file , Naming dhcpd.conf, Ask whether to overwrite the selection yes

[[email protected] ~]# vim /etc/dhcp/dhcpd.conf

subnet 192.168.1.0 netmask 255.255.255.0{
range 192.168.1.10 192.168.1.20;
option routers 192.168.1.2;
}
subnet 192.168.2.0 netmask 255.255.255.0{
range 192.168.2.10 192.168.2.20;
option routers 192.168.2.2;
}

subnet 192.168.100.0 netmask 255.255.255.0{
range 192.168.100.10 192.168.100.20;
option routers 192.128.100.2;
}

 Modify the configuration file , Set up the resource pool 

[[email protected] ~]# systemctl start dhcpd
[[email protected] ~]# systemctl stop firewalld
[[email protected] ~]# setenforce 0 

 start-up dhcpd

[[email protected] ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens33
UUID=1dc2aa9d-9273-42d2-87a5-762b3b46ed5e
DEVICE=ens33
ONBOOT=yes
IPADDR=192.168.100.131
NETMASK=255.255.255.0
GATEWAY=192.168.100.2

[[email protected] ~]#systemctl restart network 

 Modify network card information 

Modify the virtual machine network adapter mode

eNSP Zhongyun configuration

 Configure the layer 2 switch 
<Huawei>sys
[Huawei]sys SW1
[SW1]undo info-center enable
Info: Information center is disabled.

[SW1] vlan batch 10 20 100

[SW1-Ethernet0/0/1]port link-type access
[SW1-Ethernet0/0/1]port default vlan 100
[SW1-Ethernet0/0/1]undo shut
Info: Interface Ethernet0/0/1 is not shutdown.
[SW1-Ethernet0/0/1]int e0/0/2
[SW1-Ethernet0/0/2]p l a
[SW1-Ethernet0/0/2]p d v 10
[SW1-Ethernet0/0/2]undo shut
Info: Interface Ethernet0/0/2 is not shutdown.
[SW1-Ethernet0/0/2]int e0/0/3
[SW1-Ethernet0/0/3]p l a
[SW1-Ethernet0/0/3]p d v 20
[SW1-Ethernet0/0/3]undo shut
Info: Interface Ethernet0/0/3 is not shutdown.
[SW1-Ethernet0/0/3]int e0/0/4
[SW1-Ethernet0/0/4]p l a
[SW1-Ethernet0/0/4]p d v 100
[SW1-Ethernet0/0/4]undo shut
Info: Interface Ethernet0/0/4 is not shutdown.
[SW1-Ethernet0/0/4]int e0/0/5
[SW1-Ethernet0/0/5]p l t
[SW1-Ethernet0/0/5]p t a v a
[SW1-Ethernet0/0/5]undo shut
Info: Interface Ethernet0/0/5 is not shutdown.

 Configure layer 3 switch 
<Huawei>sys
[Huawei]sys SW2
[SW2]undo info-center enable
Info: Information center is disabled.

[SW2]v b 10 20 100

[SW2-GigabitEthernet0/0/1]p l t
[SW2-GigabitEthernet0/0/1]p t a v a
[SW2-GigabitEthernet0/0/1]undo shut
Info: Interface GigabitEthernet0/0/1 is not shutdown.

[SW2]int v10
[SW2-Vlanif10]ip add 192.168.1.2 24
[SW2-Vlanif10]int v20
[SW2-Vlanif20]ip add 192.168.2.2 24
[SW2-Vlanif20]int v100
[SW2-Vlanif100]ip add 192.168.100.2 24

[SW2]dhcp enable
 Turn on dhcp, Otherwise, it will report an error later 

[SW2]int v10
[SW2-Vlanif10]dhcp select relay
[SW2-Vlanif10]dhcp relay server-ip 192.168.100.2
[SW2-Vlanif10]int v20
[SW2-Vlanif20]dhcp select relay
[SW2-Vlanif20]dhcp relay server-ip 192.168.100.2
[SW2-Vlanif20]int v100
[SW2-Vlanif100]dhcp select relay
[SW2-Vlanif100]dhcp relay server-ip 192.168.100.2

Three stations PC Of IPv4 Configuration options DHCP

Enter... On the command line

ipconfig /release
ipconfig /renew

Results appear IP The address is complete