We have layer 2 switches and we are changing ISPs at our Primary School. With the new ISP we are being issued with IP addresses that we should use internally. They will split the network in 2 subnets so we can have 2 VLANs(VLAN 20 & 30). I have a DHCP server on VLAN 30 where I have set up scopes for both VLANs. If I have no layer 3 switches how can I set the IP helper address for VLAN 20 so it knows to get addresses from the DHCP server on VLAN 30? Do I need to tell the ISP to set this on their router?