I need a little assistance with a routing issue.

I have an ADSL modem with multiple IP addresses connected to my Mikrotik (ether2)... the modem is in bridge mode and so the Mikrotik initiates the connection to the ISP via PPPoE. The ISP then assigns a fixed IP address (lets say 1.1.1.100 to me via the PPPoE connection. They subsequently have routed a public subnet (lets say 1.1.2.0/27) to the router's IP, On the other end of the equation I have several servers which are connected to a switch which in turn is connected to another port (ether3) on the Mikrotik.

I don't want to have nat or firewall or anything like that in play. I simply want to be able to use the addresses on the public subnet on the servers attached to the switch on ether3 (and in turn those servers will use the Mikrotik as their default gateway.

I have been able to utilize IP's out of that subnet locally on the router with nat and port forwarding... so that end of the equation is working and I know the traffic from the IP's gets successfully to and from the router. What I don't know is how to use the Mikrotik as a "true router" rather than a NAT device and get those IP's out ether3

Assistance is much appreciated.

Mike.

As long as the ISP is routing a subnet to your device, you should be able to configure ether3 with that subnet.

For example...

Your Device (MikroTik) PPPoE WAN address is 1.1.1.2/32 and gateway configured for the ISP, the ISP is routing a subnet to you of 2.2.2.0/27 to 1.1.1.2. Ether 3 of your MikroTik gets configured as 2.2.2.1/24, devices behind ether 3 obviously configured in this subnet with a default route of 2.2.2.1.

This is all assuming that the ISP is truly routing a subnet to you.

Thanks Scott, that sounds easy enough that even I could do it GRIN!

Silly question, how does the traffic coming from devices on ether3 to their gateway 2.2.2.1 get from that point out to the internet... should the route back from 2.2.2.1 to 1.1.1.2 be getting automatically created?

I know the ISP side is ok and the traffic is coming to us as if I temporarily assign one of the IP's (ie. 2.2.2.3) to the pppoe interface instead of ether3 I can get in and out just fine. Otherwise with just the blanket 2.2.2.1/27 assigned to ether3 and the same 2.2.2.3 address assigned on a laptop with gw of 2.2.2.1 I don't seem to get anywhere

Your Device (MikroTik) PPPoE WAN address is 1.1.1.2/32 and gateway configured for the ISP, the ISP is routing a subnet to you of 2.2.2.0/27 to 1.1.1.2. Ether 3 of your MikroTik gets configured as 2.2.2.1/24, devices behind ether 3 obviously configured in this subnet with a default route of 2.2.2.1.