DHCP service

Preface

DHCP(Dynamic Host Configuration Protocol, Dynamic Host Configuration Protocol ) Is a LAN network protocol , Use UDP Agreement work , There are two main uses : Automatically assign... To internal network or network service providers IP Address , For users or internal network administrators as a means of central management of all computers .

​ One . What is? DHCP

DHCP（ Dynamic allocation IP Address ）
from internet Working group design and development
Used exclusively for TCP/IP Computers in the network automatically assign IP Address

Two .DHCP The benefits of

Reduce the workload of Administrators
Avoid the possibility of input errors
avoid IP Address conflict
When the network changes IP Address segment , There is no need to reconfigure each user IP Address
Improved IP Address utilization
Facilitate client configuration

3、 ... and .DHCP The way of distribution

Automatically assigned ： Assigned to a IP Permanent use after address （ You can directly do static ）
Manually assign ： from DHCP The server administrator specifically specifies IP Address
Dynamic allocation ： Release the after use IP Address , For other customers and

Four .DHCP Lease process

Customers and from DHCP Server get IP The process of address is DHCP Lease project

discover     1. The client sends... By broadcast discover Request... From the server IP Address
offer            2. Server received discover message , Will find one ip, Plus the corresponding lease term （ gateway 、dns The server ）
                      Form a offer message , Send to client , Inform the client that IP Address
resquest     3. The client will receive a lot of offer message , Select a reply message as your target server , To service
                      Device sending resquest Request message
ack              4. Server received resquest Ask for message , Send according to the message confirmation ack To the client
relocatio
When DHCP The server rents to the client IP The lease term of the address reaches 50% when , You need to renew the lease
The client sends directly to the server that provides the lease DHCPrequest package , Request to update the existing address lease

5、 ... and . Why use DHCP

DHCP Avoid manually setting the service ip The address photo is conflicting or wrong ,DHCP Provides security , Reliable and simple TCP/IP Network settings , Reduced configuration IP Address load .

A typical c/s Pattern
Set up a dedicated computer in the network DHCP The server , Responsible for the centralized allocation of various address parameters （ It mainly includes IP Address 、 Subnet mask 、 gateway 、 Broadcast address 、dns Server address ）, Other hosts on DHCP The server communicates , Can get IP Address

Server operation DHCP Service monitoring 67 port
Client running DHCP Program monitoring 68 port

6、 ... and .DHCP To configure

1. Configuration steps

 

 

 2. The network configuration

sw1 To configure
<Huawei>undo t m
<Huawei>system-view 
[Huawei]vlan batch 10 20 100
[Huawei]int e0/0/1
[Huawei-Ethernet0/0/1]port link-type access 
[Huawei-Ethernet0/0/1]port default vlan 10
[Huawei-Ethernet0/0/1]int e0/0/2
[Huawei-Ethernet0/0/2]port link-type access 
[Huawei-Ethernet0/0/2]port default vlan 20
[Huawei-Ethernet0/0/2]int e0/0/3
[Huawei-Ethernet0/0/3]port link-type access
[Huawei-Ethernet0/0/3]port default vlan 100
[Huawei-Ethernet0/0/3]int e0/0/5
[Huawei-Ethernet0/0/5]port link-type access 
[Huawei-Ethernet0/0/5]port default vlan 100
[Huawei-Ethernet0/0/5]int e0/0/4
[Huawei-Ethernet0/0/4]port link-type trunk 
[Huawei-Ethernet0/0/4]port trunk allow-pass vlan all 

sw2 To configure
<Huawei>undo t m
<Huawei>system-view   
[Huawei]vlan batch 10 20 100
[Huawei]int vlan 10
[Huawei-Vlanif10]ip add 192.168.1.1 24
[Huawei-Vlanif10]int vlan 20
[Huawei-Vlanif20]ip add 192.168.2.1 24
[Huawei-Vlanif20]int vlan 100
[Huawei-Vlanif100]ip add 192.168.31.2 24
[Huawei-Vlanif100]int g0/0/1  
[Huawei-GigabitEthernet0/0/1]port link-type trunk 
[Huawei-GigabitEthernet0/0/1]port trunk allow-pass vlan all 
[Huawei-GigabitEthernet0/0/1]q
[Huawei]dhcp enable 
[Huawei]int vlan 10
[Huawei-Vlanif10]dhcp select relay  
[Huawei-Vlanif10]dhcp relay server-ip 192.168.31.10
[Huawei-Vlanif10]int vlan 20
[Huawei-Vlanif20]dhcp select relay
[Huawei-Vlanif20]dhcp relay server-ip 192.168.31.10
[Huawei-Vlanif20]int vlan 100
[Huawei-Vlanif100]dhcp select relay
[Huawei-Vlanif100]dhcp relay server-ip 192.168.31.10