I'm hoping to get some advice regarding the best practice to delegate a limited Internet connection between two VLANs. In my case, one VLAN is for an office network, and the other is for guests. What I'm hoping to do is allow a certain percentage of bandwidth to the Office network with priority over the Guest network. For example if I have a 10Mbps down speed, I'd like up to 7Mbps of that to always be available to the Office if needed, otherwise, the guest connection could use it.
My main concern is that if I rate limit the guest network to say 3Mbps and the router start to drop packets over that limit, that I am wasting packets from the ISP. If I understand correctly, the ISP would be sending at say 10Mbps, then my router starts dropping anything over that limit to the guest network, isn't that wasted bandwidth that will have to be resent?
In short, rate-limiting the upload makes a lot of sense because I have full control over that with my router, but I'm not sure you can effectively rate limit down-stream traffic from the ISP as I have no control over their routers. So if you can rate limit down-stream traffic without wasting it, how do you recommend going about it?