Problem with very simple Route on Mikrotik RB750

RouterOS Beginner Basics
1

Hi Guys,

i have a seemingly easy Problem, but i can’t get it to work for my life.

I have 2 Networks.
Network one has a AVM Fritzbox as Router/Modem/Internet Connection with the IP 192.168.123.xxx/24 (Fritzbox is .1)
Network two has clients in the IP Range 192.168.10.xxx/24

Connecting both Networks is the Mikrotik RB750.
in the RB750s eth1 is the 10.x Network, eth5 is the 123.x Network.

Adresses of the Mikrotik are:

eth1 192.168.123.221 (connected to Fritzbox)
eth5 192.168.10.200 (connected to the .10.xxx Net)

Now i need Clients from the 123.x Network to be able to communicate with the Clients in the 10.x Network.

Visualisation:

pretty simple routing, right?

Sadly i’m on the edge of insanity, because i just can’t seem to get it to work. I have a static Route on the AVM Fritzbox, which redirects every request etc. directed at the 10.xxx Network right to the RB750 (because the AVM is the Gateway for the 123.xxx Clients).

That is working fine, as i see in the tracert, but the RB750 is not giving the request out to the 10.xxx Net, running it into timeout.
Tracert from a client in the 192.168.123.xxx Net to a 10.xxx Client, which shows that the request gets redirected, but shut down at the Mikrotiks eth5 (123.221)

Pings are successful:

Here is my config, maybe there is a stupid error that i can’t see:

2

Sadly i’m on the edge of insanity, because i just can’t seem to get it to work. I have a static Route on the AVM Fritzbox, which redirects every request etc. directed at the 10.xxx Network right to the RB750 (because the AVM is the Gateway for the 123.xxx Clients).

Can you post that route?

Check that:

  • FritzBox has a route to 192.168.10.0/24 gw 192.168.123.221
  • You need all the .10.x clients to have 10.1 as default gateway
  • You need the mikrotik to have .123.1 as default gateway (that’s ok judging from your screenshot)
  • Check your firewall is not getting into the way on the 750: post
/ip firewall export
/interface list export
3

thx for helping! Sadly i can’t access the Terminal right now, but i have no Firewall rules on the RB750 active right now at all, and NAT deactivated as well

Route on the Fritzbox:

List of Interfaces:




  • You need all the .10.x clients to have 10.1 as default gateway

This is the case right now. But tbh i don’t understand why this must be the GW, when there is no device with that IP (should i give the RB750 this IP?)

4

At the command prompt execute and post it:

/export hide-sensitive

You never know what sneaks into a configuration.

5

This is the case right now. But tbh i don’t understand why this must be the GW, when there is no device with that IP (should i give the RB750 this IP?)

Yes, you should either change it to 192.168.10.1, or keep the current 192.168.10.200 AND set the clients to use 192.168.10.200 as gateway.

Best approach: setting it on DHCP server > Network (I assume the 750 is running a DHCP server for the 192.168.10.x network) this way you control all clients from a single point of “provisioning”.

6

Another thing that you may need to ensure is that you are actually masquerading or dst-natting traffic from your .123 network to your .10 network.

7

Nope, no need to.

If 10.x clients use 10.x (10.1 or 10.200) as default gateway, and .123.x clients have .123.x as default gateway both networks will be reachable to each other by pure routing.