Use vswitches and routes to configure DHCP

DHCP servers manage IP addresses, so it is not surprising that vswitches and vrouters are used for related configuration. Here we will introduce these content in detail.

Network Environment: A 3550EMI switch is divided into three VLANs. vlan2 is the network where the server is located, named server, IP address segment is 192.168.2.0, subnet mask: 255.255.255.0, Gateway: 192.168.2.1, the Domain server is windows 2000 advance server and serves as a DNS server. The IP address is 192.168.2.10, vlan3 is the network where client 1 is located, the IP address segment is 192.168.3.0, The subnet mask is 255.255.255.0, And the Gateway: 192.168.3.1 is named work01, vlan4 is the network where client 2 is located, named work02, IP address segment is 192.168.4.0, subnet mask: 255.255.255.0, Gateway: 192.168.4.1, 3550 as DHCP server, ports 1-8 are divided into VLAN 2, ports 9-16 are divided into VLAN 3, and ports 17-24 are divided into VLAN 4.

DHCP server implementation function: each VLAN retains 2-10 IP addresses regardless of configuration. For example, the IP address ranges of 192.168.2.0 and 192.168.2.2 to 192.168.2.10 are not allocated.

Security requirements: VLAN 3 and VLAN 4 do not allow mutual access, but both can access VLAN 2 where the server is located. By default, the access control list rules reject all packets.

Configure the DHCP command and follow these steps:

Step 1: Create a VLAN:

 
 

  
  
Switch>en  
  
  
Switch#Vlan Database  
  
  
Switch(Vlan)>Vlan 2 Name server  
  
  
Switch(Vlan)>Vlan 3 Name work01  
  
  
Switch(vlan)>Vlan 4 Name work02 
 
 

Step 2: Set the vlan ip Address:

 
 

  
  
Switch # Config T
  
  
Switch (Config)> Int Vlan 2
  
  
Switch (Config-vlan) Ip Address 192.168.2.1 255.255.255.0
  
  
Switch (Config-vlan) No Shut
  
  
Switch (Config-vlan)> Int Vlan 3
  
  
Switch (Config-vlan) Ip Address 192.168.3.1 255.255.255.0
  
  
Switch (Config-vlan) No Shut
  
  
Switch (Config-vlan)> Int Vlan 4
  
  
Switch (Config-vlan) Ip Address 192.168.4.1 255.255.255.0
  
  
Switch (Config-vlan) No Shut
  
  
Switch (Config-vlan) Exit
  
  
/* Note: Because the ports are not configured to VLAN2, 3, 4 at this time, each VLAN will be DOWN. After the ports are allocated to each VLAN, the VLAN will get up */
 
 

Step 3: Set port global Parameters

 
 

  
  
Switch (Config) Interface Range Fa 0/1-24
  
  
Switch (Config-if-range) Switchport Mode Access
  
  
Switch (Config-if-range) Spanning-tree Portfast
  
  
 
  
  
Step 4: add the port to VLAN2, 3, 4
  
  
/* Add Port 1-8 to VLAN 2 */
  
  
Switch (Config) Interface Range Fa 0/1-8
  
  
Switch (Config-if-range) Switchport Access Vlan 2
  
  
 
  
  
/* Add Port 9-16 to VLAN 3 */
  
  
Switch (Config) Interface Range Fa 0/9-16
  
  
Switch (Config-if-range) Switchport Access Vlan 3
  
  
 
  
  
/* Add Port 17-24 to VLAN 4 */
  
  
Switch (Config) Interface Range Fa 0/17-24
  
  
Switch (Config-if-range) Switchport Access Vlan 4
  
  
Switch (Config-if-range) Exit
  
  
 
  
  
/* After this step, each VLAN will get up */
 
 

Step 5: configure the DHCP server with 3550

 
 

  
  
/* Configure available address pools and corresponding parameters for VLAN 2. You need to set several address pools for several VLANs */
  
  
Switch (Config) Ip Dhcp Pool Test01
  
  
/* Set the allocable subnet */
  
  
Switch (Config-pool) Network 192.168.2.0 255.255.255.0
  
  
/* Set the DNS server */
  
  
Switch (Config-pool) Dns-server 192.168.2.10
  
  
/* Set the gateway for this subnet */
  
  
Switch (Config-pool) Default-router 192.168.2.1
  
  
 
  
  
/* Configure the address pool used by VLAN 3 and corresponding parameters */
  
  
Switch (Config) Ip Dhcp Pool Test02
  
  
Switch (Config-pool) Network 192.168.3.0 255.255.255.0
  
  
Switch (Config-pool) Dns-server 192.168.2.10
  
  
Switch (Config-pool) Default-router 192.168.3.1
  
  
 
  
  
/* Configure the address pool and corresponding parameters used by VLAN 4 */
  
  
Switch (Config) Ip Dhcp Pool Test03
  
  
Switch (Config-pool) Network 192.168.4.0 255.255.255.0
  
  
Switch (Config-pool) Dns-server 192.168.2.10
  
  
Switch (Config-pool) Default-router 192.168.4.1
 
 

Step 6: Configure DHCP to retain unassigned addresses

 
 

  
  
Switch(Config)Ip Dhcp Excluded-address 192.168.2.2 192.168.2.10  
  
  
Switch(Config)Ip Dhcp Excluded-address 192.168.3.2 192.168.3.10  
  
  
Switch(Config)Ip Dhcp Excluded-address 192.168.4.2 192.168.4.10 
 
 

Step 7: Enable Routing

 
 

  
  
/* After a route is enabled, each VLAN host can access each other */
  
  
Switch (Config) Ip Routing
 
 

Step 8: configure the access control list

 
 

  
  
Switch(Config)access-list 103 permit ip 192.168.2.0 0.0.0.255 192.168.3.0 0.0.0.255  
  
  
Switch(Config)access-list 103 permit ip 192.168.3.0 0.0.0.255 192.168.2.0 0.0.0.255  
  
  
Switch(Config)access-list 103 permit udp any any eq bootpc  
  
  
Switch(Config)access-list 103 permit udp any any eq tftp  
  
  
Switch(Config)access-list 103 permit udp any eq bootpc any  
  
  
Switch(Config)access-list 103 permit udp any eq tftp any  
  
  
Switch(Config)access-list 104 permit ip 192.168.2.0 0.0.0.255 192.168.4.0 0.0.0.255  
  
  
Switch(Config)access-list 104 permit ip 192.168.4.0 0.0.0.255 192.168.2.0 0.0.0.255  
  
  
Switch(Config)access-list 104 permit udp any eq tftp any  
  
  
Switch(Config)access-list 104 permit udp any eq bootpc any  
  
  
Switch(Config)access-list 104 permit udp any eq bootpc any  
  
  
Switch(Config)access-list 104 permit udp any eq tftp any 
 
 

Step 9: Application access control list

 
 

  
  
/* Apply the access control list to VLAN 3 and VLAN 4. VLAN 2 is not required */
  
  
Switch (Config) Int Vlan 3
  
  
Switch (Config-vlan) ip access-group 103 out
  
  
Switch (Config-vlan) Int Vlan 4
  
  
Switch (Config-vlan) ip access-group 104 out
 
 

Step 10: end and save the configuration

 
 

  
  
Switch(Config-vlan)End  
  
  
Switch#Copy Run Start