Public IP's on LAN (over several routers?)

RouterOS General
1

I don’t think I’m in a unique situation, but I’ll be damned if I can figure it out.

My ISP gave me two class C’s. We’ve currently got a slew of routers with private networks and we’d like to distribute these public IP’s to the private clients while still keeping the routers private.

I don’t even know the first step in doing something like this. I’ve been working with MT for 3 years, but this is a totally new situation for me.

Minimalistic layout of our network:

PUBLIC --> MT---->MT--->Clients
             ^----->MT--->Clients
            ^----->MT--->Clients
           ^----->Local Network

At the moment, all of our routers have static private IP’s and are statically routed. They all give out private IP’s via DHCP.

Where do I even start on something like this?

Thanks

  • Jay
2

You just have to route your subnets through your local routers, and just be aware to void NAT for the public subnets.

regards

Faton

3

Sorry for my newbnes…but how exactly do you do that?

My public MT is 66.76.60.154
My two Class C’s are 208.180.93.0/23


I don’t even know how to set up the public MT to accept stuff from the public IP addresses on the LAN

I tried to set up a PC with a public address and was told by Windows that there was an IP conflict.

Thanks,
Jay

4

Probably your ISP has routed this public subnet 208.180.93.0/23 via 66.76.60.154, what you can do is that you can divide in smaller prefixes this /23 subnet and route via your different routers. For example if your other routers connects directly to this first router, than use e.g. 208.180.93.0/28 for connecting the routers and rest just route through. like: ip route add dst-address=208.180.93.32/27 gateway=208.180.93.2 (one of the routers connected to 208.180.93.0/28).

Regards

Faton

5

Would there be any way to do this in a way that the MT addresses remain private?

Thanks,
Jay

6

yes, just route public subnet via private IPs of your routers.

7

Don’t forget to avoid NAT for public subnet.