HI Sir, By using Mikrotik router hEX, It is possible to assign a Static Routing in Eth2 and DHCP Server in Eth3 so will run simultaneously but in different network by using 1 Cisco switch with VLAN.
Ethernet 1 = Cisco 1841 to Mikrotik hEX (WAN)
Ethernet 2 = Static Routing (Switch port 1-30) VLAN 1
Ethernet 3 = DHCP Server (Switch port 31-48) VLAN 2