I have two ISPs, ISP A connect to mikrotik router with local IP, and ISP B connect to cisco router with local IP recently I bought new mikrotik router, I want to load ballance this two ISPs with ecmp technique. I have read tutorials, but it's said two ISPs go straight in into a router, but my case each ISP going through a router first.

My question:

Can I implement load ballance ecmp on this situation? Can give me step by step how to achieve this?

Here is my current topology.

topology current condition

  • Do you deal with any incoming traffic at all? Implementing this should be doable, but it would create double-NATing through the first set of routers, and then through the second router (r3 in your topology). Having services hosted on the inside, is a bit more hassle when dealing with the double-NATed connections.
    – xstnc
    Jan 7, 2021 at 9:38
  • Balancing can be done by using the providers facing router. The other 2 don't matter.
    – Overmind
    Jan 7, 2021 at 9:46
  • Is ISP A providing a RFC1918 private net behind a NAT, or did you make the IP address up? Please edit to replace obfuscated public addresses with your real addresses, or at least reserved addresses not in use. Such as the documentation blocks or Jan 7, 2021 at 17:06
  • @xstnc yes ofcourse i make double NAT, i pick an ip address from local ip of each router and add into r3 router and use r1 and r2 gateway into r3 router, then i make nat with out interface using port that connect to r1 and r2 then i make it masquerade. it work and can use internet, but still separated network. i want load all of them in R3, how to deal with this ? Jan 8, 2021 at 2:19
  • 1
    @xstnc yes it works, i just configure everything in R3 and yes indeed there is nothing to do with the other routers, problem solve thanks. Now it can load ballance with failover system. Jan 12, 2021 at 2:23


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