Questions about QOS

[beowulf62381]

Questions:
1. I have run many speed tests at different times of the day to try and get the proper Max up/down speed for QOS. I find my speeds very dramatically by as much as 4mb/ps, Should the Max be set to an average or the best speed I have seen?

2. My ISP is comcast, and as such I get speed boost. If I set QOS to my normal bandwidth i.e. without speedboost, My network has no way of knowing that there is extra bandwidth to be used during a boost. Is this something I will simply have to accept or am I misunderstanding how QOS/speedboost works?

3. If I set bittorrent traffic to a low service class and nothing else is running on the network at that time, will my bittorrent traffic be throttled? or does the low service class only come in to affect when it wants bandwith that is needed by something running with a higher service class?

4. One of the computers in my network runs a vpn client (openvpn). I would assume that to the router this simply looks like SSL traffic to and from the local ip of the computer running the vpn client, and I could there for only apply QOS to the vpn tunnel itself, but nothing specifically inside the tunnel, is the a correct understanding or am I missing some thing?

[Eric]

1) Well.. when setting the total bandwidth for QoS you're setting the amount that is going to get split up among the hosts. This is a hard maximum -- no bandwidth greater than this amount can be used. If the bandwidth available fluctuates, this is tricky, though. Set it too high and when the available bandwidth is low, you are splitting up more than what is available, and you still get congestion. Set it too low, and you can't use some of the bandwidth available. Setting it higher errs on the side of using more of the available bandwidth at the expense of congestion when less bandwidth is available, while setting it lower errs on the side of preventing congestion at the expense of using all your bandwidth. Which of these you care more about is up to you. I suggest you experiment.

2) I don't know exactly what this "speedboost" is, but if it means your available bandwidth fluctuates you run into the problems outlined in (1)

3) Provided the service class doesn't have a hard maximum set (maximum bandwidth), it won't get throttled unless there is congestion or it hits the "total bandwidth" specified for the whole network -- this is the parameter described in (1).

4) Correct. You can't classify what application someone is running (other than that it's a VPN) if it's encrypted in a VPN tunnel.

[DoesItMatter]

Speedboost is a method from Comcast that makes it seem like you're getting a much faster connection.

What it does is usually the first few minutes, or the first few 100 Megabytes of a huge download, will go really fast, and then the transfer rate will slow down to your allocated speed.

It's meant to greatly speed up small transfer, web browsing, etc, but with big transfers, you only see the boost at the start.

As far as speeds varying through the day, its very common due to the # of people using the cable internet at the same time. When usage is peak, your max speed may seem slower because everyone in the neighborhood is using the connection, and the pipe to the neighborhood only has a set amount of bandwidth.

I used to work for Comcast - so I know a lot of their background and hype

[crisman]

I think you are speaking about burst parameters