Question about network infrastructure and assign public IPs

RouterOS General
1

Hello,
now I have a little Wisp with a mikrotik x86 router (router2) sharing (masquerade) the same public ip to our customers (less than 220).
Our customers get the private ip from the router’s dhcp server.

Now we are going to change our carrier, and they gives us a y.y.y.0/24 range of public IP adresses to a RB1200 (router1). On the wan interface (eth1) of this router there is a x.x.x.x/30 address facing the Carrier’s gateway. This carrier statically routes the y.y.y.y/24 of public ip range.

CARRIER--------WAN-eth1-ROUTER1-eth10—???ROUTING???-----eth1-ROUTER2-eth2------Customers.

That we want is change the router2 dhcp server ip range from private IP to the public ones, assigning a public IP to each customer (avoiding doing 1:1 NAT).
The questions are:

  • How can I route the entire block of public IP from Router1 to Router2 (the link between the 2 routers is wired), to get the customers internet access?
  • Is possile bridge ifaces eth1 and eth10 on router1 and give the x.x.x.x/30 to eth1 on router2?(this solution I think,if is possible, disables the possiblity from adding new routers behind router1).

Thank you in advance,

S. Grau

2

Do you need to use ROUTER2? Because it would be better if you get rid of it from the network topology.
meaning: CARRIER--------WAN-eth1-ROUTER1-eth10-LAN------Customers

If you cannot loose ROUTER2 then i suggest using a /30 private address between ROUTER1 and ROUTER2.
For routing you simply add an ip from public space on eth2 (ROUTER2) remove the Masquerading from firewall, change DHCP settings accordingly (ip pool, dns server, gateway) and that’s it.

3

Thank you very much for your response :smiley: mmmigoro,

There was a mistake in the previous post, the wired link is actually wireless link(Sorry). I attach a little network diagram.
However, I have 2 questions more:

  • In router2, there are not any srcnat rule in firewall?
  • In router1, is not necessary have any ip address from the y.y.y.y/24 to get router2 customers to be routed to internet, and did not have any srcnat rule?

Thank you again,

S. Grau
netdiagram.png

4

To answer your questions:

  • no, on router2 you don’t need a srcnat rule in firewall, because you are routing the 1.1.1.0/24 address space to internet and not masquerading it.
  • in router1 you only need a static route: /ip route add disabled=no dst-address=1.1.1.0/24 gateway=172.16.0.2, so that router1 would know how to reach 1.1.1.0/24 address space.