Hello
I have just bought a 450G and i’m amazed!
I have found and tested several wiki’s about what i’m trying to accomplish but none wih sucess 
This is what i’m trying to do:
A load balancing with a generic routing /28 public subnet. I’m not sure if i can do using 2 different ISPs, the public /28 subnet belongs to one of them. Also i’m using pppoe client in one and dhcp client in the other. (pic bellow)
So its possible? How can i do this?
Thanks in advance and nice job mikrotik!
I’m not sure if i can do using 2 different ISPs, the public /28 subnet belongs to one of them
Probably not. Usually ISPs don’t accept packets sourced from IPs that don’t belong to them unless it’s IP space that belongs to you (independent space) and has been administratively set up to be OK to be accepted. They do that to prevent customers from spoofing IP addresses.
Even if it DID work, since the IP space you have routed to you belongs to ISP A you can send traffic out ISP B but would get it back through ISP A simply because it’s their IP space - the rest of the world would route that traffic back to them, and they to you.
Note that this is not a limitation of the router - you can technically set up what you want to do on RouterOS no problem. The issue are provider policies and how BGP (the routing protocol out on the Internet) works.
Hello fewi,
Thanks for your reply!
That was one of the things i was worried about. This (i think) can be achived when using the same ISP or asking the second ISP (the one that the subnet doesnt belong) to advertice the subnet in their BGP.
The public subnet actually belongs to me and i’m the admin-c (on ripe.net) of it but it is only routable by the ISP that provided the subnet. As admin-c i’m going to request to the second ISP to include the subnet on their BGP lets just hope they do it.
Thank you.
One issue there may be that it’s just a /28. BGP usually is filtered down to /24 - most providers won’t accept more specific routes than that. But good luck.
Hello,
I’m talking with the ISP B to solve this but seems that they arent sure about what is needed.
Advertising my public range in their BGP should be enought right?
If they do that incoming and outgoing connections will came from both connections?
Thank you.
Outbound from you to them is no problem as long as they accept your traffic with those source IPs.
Incoming is trickier, and the length of the answer depends on how much you know about BGP.
Again, though - they may not be able to announce a /28. Well, they can, but their upstream probably won’t listen. And they can’t announce the whole /24 because they don’t connect to that entire /24.
i understand, so its going to be very hard to do it using two distinct providers without being (me) a AS and use BGP.
so maybe the best way is to use the same ISP on both connections, that should work without any issue.
It absolutely should.