ARP List contains every accessed public IP address

RouterOS Beginner Basics
1

Hello,

I am somewhat new to RouterOS in general, only having briefly touched it a few times over the past few years. I am slowly working towards configuring the network for load balancing and fallback, but I first need to work out the little issues I have come across.

I do not know if this is necessarily an issue, but, in summary, I have noticed that the ARP List shows every single public IP address accessed through the router, and all those IP addresses are linked to one of the ether ports setup to connect to a 5G router in bridge mode.

My current setup is that I have a MikroTik hEX S running v7.1.1 of RouterOS. ether1 is connected to a G.fast modem, which uses PPPoE to connect to the ISP. ether2 has been removed from the LAN bridge (now only ether3-5 are bridged), setup as a WAN interface, and is connected to the Huawei 5G router that has been put in bridge mode - the DHCP Client on the hEX S is setup to bind the address. ether3-4 are in use for LAN clients, with ether3 connected to a computer, and ether4 connected to a wireless router (which relays DHCP from the hEX S).

The issue in a but more detail:
I do not have this issue when using PPPoE over ether1 - ARP List shows only local IP addresses and the associated MAC addresses on the bridge interface. It begins when ether2 is enabled and the DHCP Client is “bound” on the interface - this updates the route and address lists. In this case, it seems every single public IP address accessed shows up on the ARP List and it is associated with the ether2 interface. The ARP List also includes IP addresses which were accessed on different interfaces - for example, if both the PPPoE and ether2 are enabled at the same time and connected to the internet, connections which are taking place over PPPoE will also show up on the ARP List for ether2.

I am not experienced with ARP at all. I have tried to disable ARP for the ether2 interface, but this will result in the connection to the internet just not working at all. I just do not know if this is an issue at all, or if it can be resolved if it is an issue. I just posted here because it made me curious and think it was abnormal.

Any insight into this will be appreciated. If there is more information needed, or if a copy of the configuration may help, please let me know.

TIA.

2

It means you have incorrectly configured your router. You need to properly set the subnet size (e.g. /24) and have a route via the 5G router.
This is not going to work by itself, and not by tinkering a bit with it. You need to read one of the articles that describes failover routing setup.

3

You’re certainly right about me not configuring it correctly. I went ahead and checked “Add Default Route” in the DHCP Client for the interface and the ARP List no longer lists public IP addresses (except for the Dst. Address). That’s a promising sign.

Because the IP address for the 5G connection is dynamic, I added a route in Route List with a destination of 0.0.0.0/0 and gateway ether2 (instead of the dynamic gateway). But I think this is causing the problem. How can I mitigate it?

4

I advise you to search for “failover and load balancing” in the forum. It requires quite some configuration depending on what you exactly want.