help routing static subnet via dhcp address

RouterOS General
1

Hi there,

I’m new to Mikrotik, but I have good knowledge of TCP/IP, routing, firewalling etc. So I try to get things done on this platform :wink:

My device: CCR1009-8G-1S-1S+
I have a new internet line and my ISP gives me a public static IP address with DHCP.
With this IP address, I also get a public /29 subnet, that is routed via the mentionned DHCP address,

So in detail:
My public static DHCP address is (i.e.) 123.100.77.24/24.
This includes a DHCP gateway (i.e.) 123.100.77.1
My public subnet is (i.e) 55.66.77.88/29

I have created:

  • a dhcp-client on ether-5 (to the ISP)


  • a bridge (name=bridge1) over ether1 … ether4


  • an IP address 55.66.77.89 on bridge1

Now I can connect a PC with IP address 55.66.77.90 on bridge1 and connect to the Mikrotik router.
From within WinBox the router can sucessfully PING to an external address.
But how do I correctly set up the routing of the /29 subnet on bridge1 to my ISP using 123.100.77.24?

plain config:

/interface bridge
add name=bridge1
/interface bridge port
add bridge=bridge1 interface=ether1
add bridge=bridge1 interface=ether2
add bridge=bridge1 interface=ether3
add bridge=bridge1 interface=ether4
/ip address
add address=55.66.77.89/29 comment=myISP interface=bridge1 \
    network=55.66.77.88
/ip dhcp-client
add interface=ether5
2

You don’t need to do anything with routing, it’s automatic. Router knows both where your public subnet is (on bridge1) and default route (from DHCP), that covers both incoming and outgoing traffic, router knows where to send it.