We have three internet lines from three separate ISP's. One is a 3.0mbps T1, one is a 1.5mbps T1, and the other is a 5.0 DSL line. For each of these, there's a jack on the wall, and from each of those jacks is an ethernet cable leading into one small 8 port switch. From that switch is an ethernet cable which leads to three respective WAN interfaces of three firewalls, with the LAN port of those firewalls plugging into a main switch to which all of our workstations and servers are attached. Is this ideal? We've been having issues with latency and some lost packets (but these have only occurred recently, this setup has been fine for 2 years), and the ISP's have confirmed that the lines are ok.
A tech at cisco recommended dividing the network up into subnets or using VLAN's for each device/line. Just wanted some feedback on how or whether different lines should be kept separate.