Hi,

I created a mangle rule with prerouting chain as following in my mikrotik core router:

chain=prerouting action=mark-routing new-routing-mark=mynewgate passthrough=yes src-address=x.x.x.x/24

and I also added a new default route with "mynewgate" routing mark.

When I use one of valid IP addresses in x.x.x.x/24 range in my other routers or my computer, all of my internet requests forward to my new gateway that I defined it in above mangle rule and everything is OK. But when I set one of those IP Addresses in my core mikrotik router with above mangle rule, my internet requests forward to my main default gateway without above routing mark.
Is anyone know, how can I resolve my problem?

Regards,
Hamed Sedighi
MTCNA,MTCWE,MTCRE

If I understand correctly, you mean that traffic generated in the router doesn't match your prerouting rule?
That is expected, check packet flow: http://wiki.mikrotik.com/wiki/Manual:Packet_Flow

You must put a rule in postrouting to match in-router generated traffic...