How to configure DHCP server for multiple subnets with X430-24t switches?

[Arun_Verma]

Hi All,

Our department manages its own network in our University. All the network switches (X430-24t/48t) are connected to gateway network switch(Extreme switch only) which is provided by the University.

Each Switch has own its subnet. We want to run a common DHCP server for our department. For this, we have to install a DHCP server on one machine but only machines connected to that subnet/Switch is able to get IP address from DHCP server. On each switch, we are using Bootrelay to forward DHCP request to dedicated DHCP server. Bootrelay configuration is not done at gateway switch as we don't have access to it.

Using nc and tshark, we found DHCP packets are not reaching to DHCP server from any other subnet. Do we need to configure Bootrelay configuration on gateway switch also to work our DHCP setup?

Thanks,
V Arun

[Henrique]

Exactly.

[Arun_Verma]

Hi Guys,

Thanks for fast reply.
Network configurations are as below:
IP address of Gateway switch: 10.119.1.250 Subnet: 255.255.255.0
IP address of switch1: 10.119.11.251 Subnet: 255.255.255.0
IP address of switch2: 10.119.21.251 Subnet: 255.255.255.0
IP address of switch3: 10.119.31.251 Subnet: 255.255.255.0

All switches are connected to gateway switch. A dedicated VLAN is created on each switch subnet on a port of gateway.

DHCP server is on the switch1 subnet. So, machines in switch2 subnet and switch3 subnet has to send DHCP request to DHCP server via gateway server. Bootrelay and IPforwarding are enabled on each switch but not on gateway switch as we don't have access to that switch.

We are observing that we are not receiving DHCP request packet from other subnets than switch1 subnet.

So, I want to know that as we have created VLAN on gateway switch, do we need to enable Bootrelay and IPforawarding accordingly on the gateway switch?

Thanks,
V Arun

[Arun_Verma]

Thanks for the reply.

[Henrique]

Hello Arun,

Relay agents are used to forward requests and replies between clients and servers when they are not on the same physical subnet.

That means you have to enable routing between those subnets + DHCP Relay on the gateway switch (that will be acting as the Relay agent).

[Edward_Tsui]

Hi Arun,

Did you enable ipforwarding on each client vlans? If possible, could you share your configuration?