I run personal server at home. My LAN ISP provided a static IP and ~20 Mbits/second upload speed. But the download is really slow. I also have an ADSL connection with dynamic IP but very good download speed. I use adsl through wifi (ADSL modem+wireless router)
Is there anyway to use both these connections in a single server to sum up the bandwidth? Or, to use both these connections at the same time? Is this possible in virtual mode (using virtualbox) ?
Yes, you can route certain connections on one interface and other types on another. For example, you can have all incoming traffic originating from the Internet routed through your static IP while have all outgoing traffic originating from your home go through your dynamic IP. However, the details are extremely complex and I would recommend that you read up and understand some networking fundamentals and then go on to LARTC to get more details on how to do it in Linux.
I think what you want to do is something like MLPPP to bond multiple lines together. First, I believe your ISP needs to support doing this. Also, this is usually a more advanced move so their isn't much support for this except for businesses. However, I did a quick search and found an interesting video on YouTube. I also found a PDF on how to configure multilink in a few OSs.
I hadn't tried this, but seeing how easy it is makes me want to get another cable connection.
If your ISP doesn't support multilink, I think the next best thing you can do is load balancing, meaning your computer/router would send request on the least busyest line. So you would only use one ISP modem for a connection, but any request could go out whichever connection is free. A problem this could cause is if you login to a website which uses load balancing on their end they may cache the IP you use for your state. In other words, it may appear you were logged out of a website, without warning but that is because you are using your other IP address to connect to the site and they don't realize it is still you. The other thing that may happen are sites like banks may wonder if your session was hijacked. I don't know how likely this is, but I would believe now a day some of these problems have been overcome given how mobile things are getting.
There are some routers/firewalls that can designed for load balancing (ex. Netgear FVX538). I've found a hardware solution is always better but hardware costs money.
I hope these tips help your need for speed. :)
If you have cable connection, then you don't need wireless.
Connecting thru the cable will max out your bandwidth by itself, so adding the slower wifi won't add anything.
If you're downloading from a slow source that doesn't approach your cable bandwidth, just use a multi-connection download manager.
Bonding is not possible with disparate technologies. Technologies that are commonly bonded are BDSL (bonded at the DSLAM), T1 (bonded at the DSLAM (MLFR) or ATM (MLPPP), or EoC (bonded at a Hatteras or similar device). The ISP needs to set up the bonding on their end, which involves configurations both in their equipment in the CO and their POP (if not at the CO, for Layer 3 traffic) and at the site (usually in the router). This also requires a specialized router with multiple WAN inputs.
If you are looking to use two or more connections simultaneously, you have two options. You can setup load balancing (the most common scenario) where all the connections go into a router with multiple WAN inputs and it routes traffic out WAN interfaces based on the shared load on any given interface. With this setup, no single connection from the LAN (an HTTP request, an RTP stream, etc) will ever go over any other WAN port than the one the connection was initiated on, so the max bandwidth of any connection is the max speed of the circuit it is routed over. There is no way to combine bandwidth allotment. The second scenario is fail-over. With this model there are typically just two connections - one is primary and one is secondary. The primary takes all of the traffic unless it goes down, then the router routes traffic across the secondary interface.
