SonicWall – Bandwidth Management Per User

Set user for guaranteed speed of 1Mb and max speed of 2Mb.

This is absolutely possible. Dell has an article outlining this specifically; How To Configure Bandwidth Management with limits Per IP (SW12385).

1. Enable Advanced Bandwidth Management
2. Activate bandwidth management on WAN interface and declare the interface speed
3. Generate a new bandwidth object and configure it for Per-IP Bandwidth Management.
4. Edit your default any -> any firewall rule and enable the bandwidth object you created earlier for both ingress and egress.

Also I would like to know if I can set a user for 1Mb of speed with maximum of 2 GB of download per day then have it reduced automatically to 256Kb after consuming his 2 GB for the day.

I can't find any documentation that says you can do this, so I would imagine per-ip based bandwidth management is about as close as you can get to evening the playing field for everyone. This is usually sufficient as you wouldn't stand to benefit much from limiting someone who has reached this limit if they aren't effecting anyone else (because you're already guaranteeing bandwidth evenly).

Also I would like to know if I can put such rules on applications instead of users.

Yes this is certainly possible, but is accomplished in a couple different areas. It's slightly more involved, too, since you setup everything manually versus the per-IP based solution which works across the board. Dell has another write-up for that, as well; UTM: Configuring Bandwidth Management for HTTP Websites using App Rules feature (SW11515).

1. Create Bandwidth object
2. Create Action object
3. Match that Action object to the sites you want (or don't want)
4. Map the Bandwidth object to the Action object with an App Rule

Since this is all performed under the Firewall section, it should just begin working across the board.

Good luck!