I'm trying to understand the mechanism by which bandwidth is consumed so that I can set the appropriate QoS and/or priority policies on the firewall. Here's the scenario:
Our setup is a Fortigate 60E that sits between our LAN and an AT&T Managed Router with a 10Mbps connection.
When there is no one inside our facility but me, I initiate a single request from my PC browser to a site that starts the download of a 180Mb file. I can watch the bandwidth usage graph for the internal and external interfaces immediately jump to 10Mbps (i.e. the full limit of our service) and, when the download completes, the throughput graph drops back down to 0.
Before the download completes, I initiate another browser request (pick your typical news site with images and text), the firewall graph of bandwidth usage stays at 10Mbps and my second request ultimately gets served.
My question is this: what determines how much bandwidth is allocated to my second browser request? Furthermore, since the default priority (according to Fortigate) is that all requests have a default priority of "high" how are "competing requests" resolved? Clearly it's not sequential (first come, first served) because the second request is fulfilled before the first request (download) is completed.
When there are 10 or 15 people in the office, this scenario will be repeated and amplified many times over. I don't have VOIP or email or an ecommerce server that I need to elevate or prioritize over "normal" internet use. I just have a bunch of people accessing the web simultaneously and they have an expectation of a reasonably responsive internet. So I want to prevent the first requestor having a super fast awesome experience while everyone else (i.e. the subsequent requestors) waits.
My initial thought was to set a maximum bandwidth for all requests (i.e. no request would be allocated more than say 1Mbps of bandwidth), thinking that this would prevent one request from sucking up all the bandwidth. Is this advisable? If so, how would you do it? (Traffic shaping policy? or something else?) Would changing the priority of all traffic to medium (vs. the default high priority) have a favorable effect? Would it be advisable?
I'm new to this stuff, our company is new and our IT infrastructure setup is fresh as well. Feel free to let me know if I'm just not thinking about this the right way. I've read a ton but understand less than half of the jargon that gets tossed around. A layman's explanation/response would be most welcomed!