Our network uses a edge router (3845)à firewall (ASA 5510) à two L3 Switches (3750) à Aggregate closet switches (3750) à access switches. (3560).
We are connected to our ISP with a DS3 line, and use VLANs for our inside network.
The problem we are having is low download speeds on our inside VLAN connected devices. To test I put a machine on the outside (outside address) on the same distribution switch as the edge router. My download speeds on the outside VLAN were a little over 20 Mbps (http://myspeed.visualware.com). In contrast, my download speeds on my internal VLANs (on the same distribution switch) dropped down to 2 to 3 Mbps. I tried various VLANs on the inside and they were all about the same.
I am monitoring bandwidth utilization % on the L3 Switch Gbps interfaces and they are all fractional. Could it be the virtual interfaces on the L3 switches that are the bottleneck? How would I test the bandwidth utilization if that was the case?
I will attach some screenshot attachments (.doc) of what SolarWinds is showing.
I just tested my my 'Outside' VLAN on a switch in my office, and the download speeds were again about 24 Mbps. I then connected to our staff VLAN on the same switch and it dropped down to 1.5 Mbps.