Hi,

Is it possible to exchange marks of packets betwean two routers?

http://wiki.mikrotik.com/wiki/Manual:IP/Firewall/Mangle

No. As per the documentation, they are only used internally.

Is it possible to exchange marks of packets betwean two routers?

Not directly, but you may be able to achieve the same result in a different way. For example, if the routers are connected via a common layer 2 network you might be able to use different VLANs to carry distinct traffic then re-mark the packets at the far end.

Thank you for a reply. I'll do it using vlans.

you can use Diffserv/TOS also ;p