What is a good approach to develop internet access failover system?

Question

I have 3 internet providers in the same environment, but distributed in different points/hosts. Sometimes a link is off while the others are okay. My idea is to centralize all connections in a server to guarantee that all hosts are online since at least one internet provider is working properly.

But I have a few questions.

1. Is is possible to share all internet connections and serve them as they were a unique provider? So, when one is off the others could take care of the signal?

2. In case the first question results in negative answer, what do I need to do in order to start developing a server that handles 3 simultaneous internet connections?

I have done network sharing before using Debian as a server, but never did failover system before. Thus, any point, tip, tutorial, online material, etc, is welcome.

Thanks in advance.

Answer 1

YEs you can use all ISPs at the same time and also use as primary, secondary ISPs. Primary is the one which would be used by default and secondary would be used in case of failure of primary.

To know do this things, there are two options known to me.

1) You can use multiple Routers and configure them for redundancy protocols such as HSRP, VRRP or GLBP. You can find more about the configuration on youtube.

2) You can also implement this if you have a hardware firewall such as SonicWall, FortyGate, PIX or Juniper. There you can have multiple ISP connections and you can create the strategy about how the internet sharing could be done. You would also be able to more help on configuring firewall on youtube if you search for it.

There might be other ways also but I shared the ones I currently use. I would really like to know any other methods that could also be used for the same.

Answer 2

When it comes to ISP redundancy, if your circumstantes allow it i.e. you own a Public IP address or subnet; you could use BGP protocol which would connect you to internet with more than one ISP. They would both point your network from internet ad you could assign priority. That's a method.

Secondly you could have a load balancer like a Peplink device.You have multiple WAN ports on load balancers and can establish clever and flexible algorithms on it. You don't have to use such a device to use 1 active connection. In theory you could have 3 ISPs at the same time and divide your traffic on the way to the internet based on your source addresses, destination addresses and protocols for example.

Thirdly, you could use things like IP SLA commands to costantly check if one ISP available, as soon as it goes down the traffic could be diverted to second ISP. In order to do this you should have L3 devices that can support these capabilities.

Hope this helps.