3550 Configuring DHCP Relay Agent Project Example
There are many discussions on the network, but most of them have errors and omissions. After following the configuration of "IP HELPER-ADDRESS DHCP server address" introduced online, the project found that the client could not obtain the IP address from the DHCP server. I recently happened to configure 3550 as the DHCP server relay agent. I was confused for a long time at first. Later, I searched for information online and sought help from everyone on the forum. Finally, I passed the test in the project. In order to avoid everyone from encountering such situations in the project, I wrote down the configuration process for everyone as a reference.
Network environment: a 3550EMI switch, divided into three vlans and vlan2, which are 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, domain server is Windows 2000 advance server, and it also serves as a DHCP server and DNS server, IP address is 192.168.2.10, vlan3 is the network where the client 1 is located, IP address segment is 192.168.3.0, subnet mask: 255.255.255.0, gateway: 192.168.3.1 is named work01, vlan4 It is the network where client 2 is located, named work02, the IP address segment is 192.168.4.0, the subnet mask: 255.255.255.0, and the gateway: 192.168.4.1.
3550 is divided into VLAN 2, ports 9-16 are divided into VLAN 3, and ports 17-24 are divided into VLAN 4.
The configuration commands and steps are as follows:
Step 1: Create a VLAN:
Switch>Vlan Database
Switch(Vlan)>Vlan 2 Name server
Switch(Vlan)>Vlan 3 Name work01
Switch(vlan)>Vlan 4 Name work02
Step 2: Enable DHCP Relay Agent:
/*A key step, if the following two commands are missing, use "IP HELPER-ADDRESS DHCP Server Address" to specify the DHCP server in the VLAN, and the client still cannot obtain the IP address*/
Switch>Enable
Switch#Config t
Switch(Config)Service Dhcp
Switch(Config)Ip Dhcp Relay Information Option
Step 3: Set the VLAN IP address:
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: Since the ports are not configured to VLAN2, 3, 4 at this time, each VLAN will DOWN. After the ports are allocated to each VLAN, the VLAN will rise*/
Step 4: Set the global port parameters
Switch(Config)Interface Range Fa 0/1 - 24
Switch(Config-if-range)Switchport Mode Access
Switch(Config-if-range)Spanning-tree Portfast
Step 5: Add ports to VLAN2, 3, 4
/*Add ports 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 6: Set the DHCP server address in VLAN3 and 4
/*DHCP server address is not required in VLAN 2*/
Switch(Config)Int Vlan 3
Switch(Config-vlan)Ip Helper-address 192.168.2.10
Switch(Config)Int Vlan 4
Switch(Config-vlan)Ip Helper-address 192.168.2.10
Step 7: Enable routing
/*After routing is enabled, hosts between VLANs can access each other. If you need to further control access rights, it needs to be applied to the access control list*/
Switch(Config)Ip Routing
Step 8: End and save the configuration
Switch(Config-vlan)End
Switch#Copy Run Start
Article entry: aaadxmm Editor in charge: aaadxmm
There are many discussions on the network, but most of them have errors and omissions. After following the configuration of "IP HELPER-ADDRESS DHCP server address" introduced online, the project found that the client could not obtain the IP address from the DHCP server. I recently happened to configure 3550 as the DHCP server relay agent. I was confused for a long time at first. Later, I searched for information online and sought help from everyone on the forum. Finally, I passed the test in the project. In order to avoid everyone from encountering such situations in the project, I wrote down the configuration process for everyone as a reference.
Network environment: a 3550EMI switch, divided into three vlans and vlan2, which are 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, domain server is Windows 2000 advance server, and it also serves as a DHCP server and DNS server, IP address is 192.168.2.10, vlan3 is the network where the client 1 is located, IP address segment is 192.168.3.0, subnet mask: 255.255.255.0, gateway: 192.168.3.1 is named work01, vlan4 It is the network where client 2 is located, named work02, the IP address segment is 192.168.4.0, the subnet mask: 255.255.255.0, and the gateway: 192.168.4.1.
3550 is divided into VLAN 2, ports 9-16 are divided into VLAN 3, and ports 17-24 are divided into VLAN 4.
The configuration commands and steps are as follows:
Step 1: Create a VLAN:
Switch>Vlan Database
Switch(Vlan)>Vlan 2 Name server
Switch(Vlan)>Vlan 3 Name work01
Switch(vlan)>Vlan 4 Name work02
Step 2: Enable DHCP Relay Agent:
/*A key step, if the following two commands are missing, use "IP HELPER-ADDRESS DHCP Server Address" to specify the DHCP server in the VLAN, and the client still cannot obtain the IP address*/
Switch>Enable
Switch#Config t
Switch(Config)Service Dhcp
Switch(Config)Ip Dhcp Relay Information Option
Step 3: Set the VLAN IP address:
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: Since the ports are not configured to VLAN2, 3, 4 at this time, each VLAN will DOWN. After the ports are allocated to each VLAN, the VLAN will rise*/
Step 4: Set the global port parameters
Switch(Config)Interface Range Fa 0/1 - 24
Switch(Config-if-range)Switchport Mode Access
Switch(Config-if-range)Spanning-tree Portfast
Step 5: Add ports to VLAN2, 3, 4
/*Add ports 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 6: Set the DHCP server address in VLAN3 and 4
/*DHCP server address is not required in VLAN 2*/
Switch(Config)Int Vlan 3
Switch(Config-vlan)Ip Helper-address 192.168.2.10
Switch(Config)Int Vlan 4
Switch(Config-vlan)Ip Helper-address 192.168.2.10
Step 7: Enable routing
/*After routing is enabled, hosts between VLANs can access each other. If you need to further control access rights, it needs to be applied to the access control list*/
Switch(Config)Ip Routing
Step 8: End and save the configuration
Switch(Config-vlan)End
Switch#Copy Run Start
Article entry: aaadxmm Editor in charge: aaadxmm