Routing one ip across a tunnel.

RouterOS General
1

I have seen mikrotiks where one ip/32 was assigned to an interface with no subnet in sight.

What does this even mean to have a stand alone intefface with a standalone IP/32 on it, how is it used?

What I need to do is route an single IP across a tunnel between two mikrotiks, to reach a host that would normally have
that IP but is now for a while in the wrong physical location to have it.

So 10.0.0.1/24 is on a mikrotik1 in one location with hosts connected to it and mikrotik1 acts as their default gateway.

There is a simple IPIP tunnel between the mikrotik1 and another mikrotik2 in a another far distant location.

That second mikrotik2 has its own independent unrelated hosts and subnets and default gateways, but there is a host on one of its interfaces that needs 10.0.0.15/32. Notice I can not give it a new subnet for its new location. Its a problem in renumbering hundreds of domains that point to 10.0.0.15/32 that I do not have control over their DNS.

That single host’s default route may go out the local default route using a second proper subnet on its one interface or it can go back across the tunnel first before going out to the net.

How is this done? How do I get the single IP to the host and how do I assign it to its interface as /32 or /24 or what. Please be specific, thanks for your time.

Homer W Smith
CEO Lightlink Internet.

2

It’s a unique “router ID” for OSPF and MPLS.

“The router ID is the highest IP address on the box—or, if a loopback exists, the loopback becomes the router ID. It is highly recommended that you define a loopback address so that it will be elected as a router ID. One good reason is that, if a link is elected as a router ID instead of a loopback and that link goes down, the router ID will be changed. When a router ID changes, it breaks the virtual link also. On the other hand, if a loopback is defined as a router ID, the router ID always will be the same.”
(Cisco Troubleshooting IP Routing Protocols)

“It is important that all loopback addresses in an MPLS network are host addresses, that is, with a mask of 255.255.255.255. Using a shorter mask can prevent MPLS-based VPN services from working correctly.”
(Cisco MPLS Controller Software Configuration Guide)

3

OK, wisdom prevails.

Thank you very much.

Homer W Smith
CEO Lightlink Internet

4

Specific to your requirements you probably want to stretch layer 2. At the far side, Mikrotik-2, give it an IP in the 10.0.0/24 range and set that IP as the default gateway for 10.0.0.15 host as that IP. This eliminates the need for any significant trickery and you just terminate the EoIP tunnel in a bridge or VLAN and present that to a host as an access port.