How to disable ECMP on BGP?

[ericdriver]

Hi eduplant,

Thank you for your answer. You are right, the client router (v7.5) has 2 routes to the same IP address range over both VPNs. Both routes are coming from BGP:

/ip/route> print
Flags: D - DYNAMIC; X, I, A - ACTIVE; c, s, b, d, y - COPY; + - ECMP
Columns: DST-ADDRESS, GATEWAY, DISTANCE
#      DST-ADDRESS       GATEWAY          DISTANCE
  DAb+ 172.20.0.0/16     10.20.0.1              20
  DAb+ 172.20.0.0/16     10.40.0.1              20

But because VPNs are established to 2 different offices, ECMP becomes a real issue. In earlier versions flag “+”, which is ECMP wasn’t there and everything was working perfectly. Since ECMP for BGP was implemented in (at least) v7.5, I thought there must be a way to stop / disable it per BGP connection.

Or, if I may, it could be a good idea not to start it automatically. If some one needs it, there might be an option to turn it on. For example, a router doesn’t automatically create 4095 VLANs just in case if a user needs all of them.

If you make an adjustment to make it pick a single preferred path to the BGP nexthop, the resulting routes should follow.

That’s what I’m talking about. I don’t know how to disable automatic multipath. The only adjustments I could think of is a work around using Mangle rules (and it works by the way), but this is really not a solution, this is just a band aid. So, it would be great if someone tells me how to disable ECMP over BGP.

Kind regards

P.S. I know many people asked for ECMP for BGP. I’m not saying it’s a bad idea, I’d just like to know how to turn it off if need be.

Hi ghostt, could you share your BGP configuration? Here it said that BGP mulipath has not ready yet http://forum.mikrotik.com/t/bgp-ecmp-doesnt-work/162109/1 , but on your screen I see clear BGP multipath.