Hi,

although I read several threads plus docs, I would like to have situation for us clearer, by finding out, which way should we go ...

We currently have 2x 3/1 mbit line from two ISPs. In the future, we want to buy from one one ISP further, and the second one let as a backup.

My questions are:

1) Can I use bonding here? I know docs state it needs two ethernet devices. On of our ISPs is connected via radio, but we could add RB in front of it, and have two ethernets. But from what I read I am simply not able to understand, if we can "bond" two lines from different ISPs on our end?


2) As I suspect not, let's continue with ECMP or policy routing. I looked into docs, and found similar policy routing example - my idea was to mangle routing packets, and to let different networks go via different ISPs.

But I want to solve following - if one line fails, let's its traffic to go via another one, .... and vice versa. The example in docs shows situation with three gateways. My question is - if the second line fails (gw2):

0000 gw1
0000 gw2

- how can I get packets go via gw1? Does router OS use "rotation", so that if that does not find proper route, it starts looking it from the beginning? I am not sure - what is more, those packets are mangled. Or should I do it as follows?

0000 gw1 mangled
0000 gw2 mangled
0000 gw1
0000 gw2

? Simply put - if one gw fails, let's pass it via the second one. There is no general third backup gw as in docs ....

3) Can I "catch" such an event? I mean - if e.g. 6mbit line fails, and our "backup" is some 3mbit - I can very easily get congested line. Not sure shaping/prioritisation would work, so my idea was to dynamically redefine queues, or to simply pass-thru only the lucrative customers (as businesses) etc, not home users ... What is your idea here?

Thanks a lot,
Petr