Running 2 Networks on 1 interface without Vlans

RouterOS General
1

Hi,
I want to configure 2 networks on a single ether-2 port to have both DHCP and Static clients from 2 different IP Pools.

Requirement:

  • IP Pool 0 on Ether-2 Network 192.168.0.1/24 with DHCP
    for all new clients to get IP from DHCP without any configuration

  • IP Pool 1 on Ether-2 Network 192.168.20.1/24 with Static Only
    for selective clients who will configure static IPs

Or

  • 1 x DHCP runing for all new / old clients

  • 1 x PPPoE Server any client who wants to dial in and get IP from other Pool

  • Both have to be on the same RB port simultaneously

  • No Vlans

  • All Clients should be able to access internet through Load balancing already in place through 3 WANs

  • All clients should be able to connect as DHCP Clients or Static Only clients whenever they want to switch without any setting required at RB

Equipment:

  • RB750Gr2 running RoS7.8
  • Multiple Child routers down in the line
2

Wrong question,
Explain what the users need for traffic flow… contorting a config is always possible but the best holistic approach integrates the entire config with context.

3

Let me explain the scenario a little

I have RB750 running load balancing with 3 WANs and a LAN on 1 of its ports to all clients (mostly have a non RB routers) and these router serves clients through ethernet to Window PCs or through WLAN to Laptops and smartphones etc. Everything it running on DHCP.

I want that the setup should remain the same as before (DHCP in effect as before) but if i need to shift a particular child router or a directly connected client to a different subnet, i just put in a static IP on them or set a pppoe connection on them so they get IP from a different subnet / network without changing any switch ports or configuring VLANs.
If a router resets then it should fall back to old DHCP IP.

4

If the 2nd subnet is “static only”, only create one DHCP Server. But two DHCP networks, one for each subnet. Then in the DHCP Server > Leases change any to use the static address in the 192.168.20.0/24 (or just statically assign the 192.168.20.0/24 on the devices). The trick is to use only one ip pool and one server, but AFAIK the reservations just need to a matching DHCP server network.

The router’s LAN would need BOTH /ip address (192.168.20.1/24 and 192.168.0.1/24) added as the address for the bridge/LAN.

5

Thanks @Amm0 it worked

  • I added another IP address 192.168.20.1 on LAN interface. So now LAN (on Ether-2 Port) has 192.168.15.1 and 192.168.20.1
  • Added another Network as 192.168.20.0/24 with Gateway 192.168.20.1
  • DHCP running on same LAN (Ether-2 Port) as 192.168.15.0/24 network
  • Now i can either manually assign IPs from 192.168.20.0 network on devices themselves or in IP>DHCP Server>Leases as well a use DHCP on the devices as before on 192.168.15.0 network
6

Can you explain what the purpose of a different subnet / network is?

If if is security, then I can think of no way to do what you are asking for, given only the equipment you have specified.

You can run multiple subnets in the same broadcast domain, as long as you only need one dhcp server, but because of the way that dhcp works (the discover packets are sent with ethernet broadcasts, so any dhcp server on the network will see the “request for ip configuration” coming from any host on the broadcast domain.

Remember that anyone can change the ip address that is on their host/router.

7

IDK the OP’s rational. Legacy device with fix IP, migration to new IP numbering, multicast - there are valid reasons. Certainly if the devices in each subnet have different security profile/risk/etc, Layer 2 segmentation obvious better approach. If it’s enforcing kid control etc… well, I suspect your motivated teenage may figure out to change the IP address as Buckeye suggests.

But it’s this kinda flexibility that’s actually nice in RouterOS.

8

It was not for kid control. i just needed a simple enough solution to give few devices better access to some resources on the network as well as better speed with a separate queue and blocking all others, without arousing suspicion.
I know i can make separate queues but dont want to do it on the main network.
Actually a few clients cleverly keep changing there IP address and smartphones have mac randomization.
I don’t want to run hotspot or Vlans as they need user side configs.