How to connect 3 Internet gateways on the same subnet on Debian?

Question

Debian

Hello.
Debian 10 available
Network settings config

auto eth0
iface eth0 inet static
address 192.168.3.98
netmask 255.255.248.0
gateway 192.168.0.101

We have 3 ISPs on the same subnet.
Actually if I change the gateway to 192.168.0.102 or 192.168.0.103 . I have a different provider. The IP address itself remains the same.
How can I activate 3 gateways at the same time? so that from the outside they can contact me from three different IPs at the same time.
In other words, how to set 3 gateways at the same time.
This is if you do a crutch at all,
put 4 servers that will listen to 3 gateways and redirect to one local computer and back. So 100% will do, but damn why bother with 4 servers instead of 3. I'm sure someone can tell you how to do it right
. For example, in this case, my traffic goes through provider No. 1
IP address 192.168.2.200
Get hooked 255.255.248.0
Gateway 192.168.0.101 in
this case my traffic goes through provider # 2
IP address 192.168.2.200

Answer 1

There can be only one gateway within one subnet, alternatives - of varying degrees of crookedness. What you want is done by setting up multiple interfaces. In order to be able to get through to you through three different channels, you need to at least set up sending responses through the same interface that you received.

Answer 2

at the same time the packet does not go through the gateway. Goes through the one indicated.
For automation, there is BGP and OSPF.
I do not quite understand how you have one IP address from different providers.
If the office is small, you can raise trite BGP on Mikrotik by agreement with providers. But not every provider will meet you with such conditions.
Well, or set up channel reservation on the gateway. The implementation depends on the gateway.
In any case, the route will be the same.
In any case, it's not clear what you mean by "I have another provider connecting. The IP address itself remains the same."