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Learning diary - (routing and switching technology) DHCP (Dynamic Host Configuration Protocol)

2022-07-23 12:51:00 【Make money and marry sweet】

One 、 Related knowledge

DHCP（ Dynamic Host Configuration Protocol ） Allocate to customers in a mobile way TCP/IP Information

advantage ：

Reduce the workload of Administrators
Reduce the possibility of input errors
avoid IP Conflict
When the network changes the network segment , There is no need to reconfigure each computer IP
Computer mobility does not require reconfiguration IP
Improved IP Address utilization

working process

notes ： When there are multiple servers , The client will first choose the server that responds to it

When DHCP The client has a lease term of 50% when ： Renew lease , The client sends DHCPRequest package
When DHCP The client has a lease term of 87.5% when ： Enter the re application status , The client sends DHCPDiscover package
Use ipconfig/renew The command to DHCP Server send DHCPRequest package . If DHCP The server is not responding , The client will continue to use the current configuration .
Use ipconfig/release command ： Of the client TCP/IP Contact stopped (IP 0.0.0.0 Subnet mask ：0.0.0.0), The server will release IP Assign to other clients .

DHCP Is based on Client/Server Working mode ,DHCP The server assigns to the host that needs dynamic configuration IP Address and host configuration parameters .

DHCP There are three mechanisms for distribution IP Address ：

Automatically assigned ：DHCP Assign permanent IP Address
Dynamic allocation ：DHCP The assignment to the client will expire after a period of time IP Address （ Or the client can automatically release IP Address ） Default （ default ） The term of the lease is 1 God .
Manual configuration ： Configured by the network administrator IP Address

Of the three ways of address assignment , Only dynamic allocation can reuse addresses that the client does not need

Two 、 Related examples

1、 Routing operation DHCP The server

step
1、 open DHCP service
2、 Configure the address of the router interface and open
3、 To configure DHCP agreement

topology ：

Code ：

Router>en

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#host R1

R1(config)#se

R1(config)#ser

R1(config)#service dhc

R1(config)#service dhcp Turn on DHCP service

R1(config)#INT

R1(config)#INTerface g

Configure router
R1(config)#INTerface gigabitEthernet 0/0
R1(config-if)#ip add
R1(config-if)#ip address 192.168.1.254 255.255.255.0
R1(config-if)#no sh
R1(config-if)#no shutdown

R1(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up

R1(config-if)#e

R1(config-if)#exit

R1(config)#ip dh

R1(config)#ip dhcp po

R1(config)#ip dhcp pool SYJ To build a DHCP Address pool （SYJ It's the name ）

R1(dhcp-config)#net

R1(dhcp-config)#network 192.168.1.0 255.255.255.0 Divide the address pool into ranges

R1(dhcp-config)#de

R1(dhcp-config)#default-router 192.168.1.254 Set the gateway address

R1(dhcp-config)#dns

R1(dhcp-config)#dns-server 192.168.1.1 DNS Domain name address

R1(dhcp-config)#e

R1(dhcp-config)#exit

R1(config)#ip dh

R1(config)#ip dhcp ex

Put some useless IP Address exclusion
R1(config)#ip dhcp excluded-address 192.168.1.1
R1(config)#ip dhcp excluded-address 192.168.1.2 192.168.1.10
R1(config)#ip dhcp excluded-address 192.168.1.254

R1(config)#ex

R1(config)#exit

R1#

%SYS-5-CONFIG_I: Configured from console by console

R1#

result ：PC0 use DHCP Protocol auto access IP Address

2、 The layer-2 switch works DHCP The server

topology ：

Corresponding code ：

Switch>en

Switch#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Switch(config)#host

Switch(config)#hostname S1

Divide VLAN
S1(config)#vlan 10
S1(config-vlan)#e
S1(config-vlan)#exit
S1(config)#vlan 20

S1(config-vlan)#e

S1(config-vlan)#exit

S1(config)#in

take 4 Interfaces are divided into corresponding VLAN
S1(config)#interface f
S1(config)#interface fastEthernet 0/1
S1(config-if)#sw
S1(config-if)#switchport mo
S1(config-if)#switchport mode a
S1(config-if)#switchport mode access
S1(config-if)#sw
S1(config-if)#switchport a
S1(config-if)#switchport access vlan 10
S1(config-if)#e
S1(config-if)#exit
S1(config)#int
S1(config)#interface f
S1(config)#interface fastEthernet 0/2
S1(config-if)#sw
S1(config-if)#switchport mo
S1(config-if)#switchport mode ac
S1(config-if)#switchport mode access
S1(config-if)#sw
S1(config-if)#switchport ac
S1(config-if)#switchport access vlan 10
S1(config-if)#e
S1(config-if)#exit
S1(config)#int
S1(config)#interface fastEthernet 0/3
S1(config-if)#switchport mode access
S1(config-if)#switchport access vlan 20
S1(config-if)#e
S1(config-if)#exit
S1(config)#interface fastEthernet 0/4
S1(config-if)#switchport mode access
S1(config-if)#switchport access vlan 20

S1(config-if)#e

S1(config-if)#exit

VLAN surface
S1(config)#do show vlan brief
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/5, Fa0/6, Fa0/7, Fa0/8
Fa0/9, Fa0/10, Fa0/11, Fa0/12
Fa0/13, Fa0/14, Fa0/15, Fa0/16
Fa0/17, Fa0/18, Fa0/19, Fa0/20
Fa0/21, Fa0/22, Fa0/23, Fa0/24
Gig0/1, Gig0/2
10 VLAN0010 active Fa0/1, Fa0/2
20 VLAN0020 active Fa0/3, Fa0/4
1002 fddi-default active
1003 token-ring-default active
1004 fddinet-default active
1005 trnet-default active

S1(config)#int

open VLAN , Configure the corresponding address
S1(config)#interface vlan 10
S1(config-if)#
%LINK-5-CHANGED: Interface Vlan10, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan10, changed state to up
S1(config-if)#ip add
S1(config-if)#ip address 192.168.10.1 255.255.255.0
S1(config-if)#no sh
S1(config-if)#no shutdown
S1(config-if)#e
S1(config-if)#exit
S1(config)#interface vlan 20
S1(config-if)#
%LINK-5-CHANGED: Interface Vlan20, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan20, changed state to up
S1(config-if)#ip address 192.168.20.1 255.255.255.0
S1(config-if)#no sh
S1(config-if)#no shutdown

S1(config-if)#e

S1(config-if)#exit

S1(config)#ser

S1(config)#service DH

S1(config)#service DHcp open DHCP service

S1(config)#ip dh

S1(config)#ip dhcp poo

S1(config)#ip dhcp pool vlan10 establish DHCP Address pool

S1(dhcp-config)#net

S1(dhcp-config)#network 192.168.10.0 255.255.255.0 Divide the address pool into a network segment

S1(dhcp-config)#de

S1(dhcp-config)#default-router 192.168.10.1 configure gateway

S1(dhcp-config)#dn

S1(dhcp-config)#dns-server 1.1.1.1 Domain name service

S1(dhcp-config)#ex

S1(dhcp-config)#exit

S1(config)#ip

S1(config)#ip dh

S1(config)#ip dhcp po

S1(config)#ip dhcp pool vlan20

S1(dhcp-config)#net

S1(dhcp-config)#network 192.168.20.0 255.255.255.0

S1(dhcp-config)#de

S1(dhcp-config)#default-router 192.168.20.1

S1(dhcp-config)#dn

S1(dhcp-config)#dns-server 2.2.2.2

S1(dhcp-config)#ex

S1(dhcp-config)#exit

S1(config)#ip ah

S1(config)#ip dh

S1(config)#ip dhcp ex

Get rid of the unused IP Address
S1(config)#ip dhcp excluded-address 192.168.10.1
S1(config)#ip dhcp excluded-address 192.168.10.2 192.168.10.100
S1(config)#ip dhcp excluded-address 192.168.20.1
S1(config)#ip dhcp excluded-address 192.168.20.2 192.168.20.200

S1(config)#ex

S1(config)#exit

S1#

%SYS-5-CONFIG_I: Configured from console by console

result ：

DHCP relay

topology ：

Related codes

R1：

Router>en

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#host

Router(config)#hostname R1

R1(config)#int g

Configure interface IP Address
R1(config)#int gigabitEthernet 0/0
R1(config-if)#ip add
R1(config-if)#ip address 172.16.1.1 255.255.255.0
R1(config-if)#no sh
R1(config-if)#no shutdown
R1(config-if)#
%LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up
R1(config-if)#e
R1(config-if)#exit
R1(config)#int gigabitEthernet 0/1
R1(config-if)#ip address 172.16.12.1 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#
%LINK-5-CHANGED: Interface GigabitEthernet0/1, changed state to up

R1(config-if)#e

R1(config-if)#exit

R1(config)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up

R1(config)#route

To configure RIP route
R1(config)#router rip
R1(config-router)#net
R1(config-router)#network 172.16.1.0
R1(config-router)#network 172.16.12.0
R1(config-router)#ver
R1(config-router)#version 2

R1(config-router)#end

R1#

% Unknown command or computer name, or unable to find computer address

R1#show ip ro

The configured routing table
R1#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
C 172.16.1.0/24 is directly connected, GigabitEthernet0/0
L 172.16.1.1/32 is directly connected, GigabitEthernet0/0
R 172.16.2.0/24 [120/1] via 172.16.12.2, 00:00:07, GigabitEthernet0/1
C 172.16.12.0/24 is directly connected, GigabitEthernet0/1
L 172.16.12.1/32 is directly connected, GigabitEthernet0/1

R1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R1(config)#ser

To configure DHCP
R1(config)#service dhcp
R1(config)#ip dhc
R1(config)#ip dhcp pool SYJ
R1(dhcp-config)#net
R1(dhcp-config)#network 172.16.1.0 255.255.255.0
R1(dhcp-config)#de
R1(dhcp-config)#default-router 172.16.1.1
R1(dhcp-config)#dns
R1(dhcp-config)#dns-server 1.1.1.1
R1(dhcp-config)#e
R1(dhcp-config)#exit
R1(config)#%DHCPD-4-PING_CONFLICT: DHCP address conflict: server pinged 172.16.1.1.
R1(config)#ip dhc
R1(config)#ip dhcp poo
R1(config)#ip dhcp pool JTN
R1(dhcp-config)#net
R1(dhcp-config)#network 172.16.2.0 255.255.255.0
R1(dhcp-config)#de
R1(dhcp-config)#default-router 172.16.2.1
R1(dhcp-config)#dns
R1(dhcp-config)#dns-server 2.2.2.2

R1(dhcp-config)#e

R1(dhcp-config)#exit

R1(config)#ip dh

R1(config)#ip dhcp ec

R1(config)#ip dhcp ex

R1(config)#ip dhcp excluded-address 172.16.1.1
R1(config)#ip dhcp excluded-address 172.16.2.1

R1(config)#

R2:

Router>en

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#host

Router(config)#hostname R2

R2(config)#int g

Configuration interface IP Address
R2(config)#int gigabitEthernet 0/0
R2(config-if)#ip address 172.16.2.1 255.255.255.0
R2(config-if)#no sh
R2(config-if)#no shutdown
R2(config-if)#
%LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up
R2(config-if)#e
R2(config-if)#exit
R2(config)#int gigabitEthernet 0/1
R2(config-if)#ip address 172.16.12.2 255.255.255.0
R2(config-if)#no s
R2(config-if)#no sh
R2(config-if)#no shutdown

R2(config-if)#

%LINK-5-CHANGED: Interface GigabitEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up

R2(config-if)#e

R2(config-if)#exit

To configure RIP agreement
R2(config)#route r
R2(config)#route rip
R2(config-router)#net
R2(config-router)#network 172.16.2.0
R2(config-router)#network 172.16.12.0
R2(config-router)#ver
R2(config-router)#version 2

R2(config-router)#end

R2#

%SYS-5-CONFIG_I: Configured from console by console

R2#show ip rou

Routing table
R2#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks
R 172.16.1.0/24 [120/1] via 172.16.12.1, 00:00:01, GigabitEthernet0/1
C 172.16.2.0/24 is directly connected, GigabitEthernet0/0
L 172.16.2.1/32 is directly connected, GigabitEthernet0/0
C 172.16.12.0/24 is directly connected, GigabitEthernet0/1
L 172.16.12.2/32 is directly connected, GigabitEthernet0/1

R2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R2(config)#ser

R2(config)#service dhc

R2(config)#service dhcp Be sure to turn on DHCP service

R2(config)#int

R2(config)#interface g

R2(config)#interface gigabitEthernet 0/0 Access interface

R2(config-if)#ip help

R2(config-if)#ip helper-address 172.16.12.1 To configure DHCP relay

R2(config-if)#e

R2(config-if)#exit