I have this scenario where SW1 and SW2 are connected to each other from the interfaces Ether9 and Ether10. If we leave it this way, we will end up having an alternate port somewhere and 1 link cannot be used, so I need to apply bonding by using the open standard 802.3ad and see if the bonding will happen.

First thing we should check whether those interfaces on the 2 switches have same speed and duplex. By default, on MikroTik Auto-negotiation is enabled and this could cause the issue, so better to hard code the speed and duplex on each interface ourselves. I will show you how you can do this on one interface then you know how to apply it to all other interfaces.

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As you can see, I have set Ether9 of SW1 to 100 Mbps speed and a Full duplex. Same I did for Ether 10 on SW1 and the 2 other interfaces on SW2.

Excellent! Now it is time to start doing the bonding. I will start with SW1. Remember we have to use 802.3ad mode and the link monitoring should be MII.

Same I should do on SW2 as the following:

If you see on SW2, the bonding1 interface, which was dynamically created, is running

Also you see that in this interface it has been shown on the interface list with all other interfaces and has a type as Bonding as the following:

On SW1, you will see the same result. So now Bonding is formed and both switches have to use the 2 links to send and receive traffic at the same time, which means we are increasing the throughput.

To try this, I will put an IP address on both bonding interfaces of the 2 switches so it is from the same range and I will use a Bandwidth test.

Let’s put an IP on SW1 bonding interface of 192.168.0.1/24

I will put an IP address of 192.168.0.2/24 on the bonding 1 interface of SW2.

I will ping from SW2 to SW1 IP address 192.168.0.1

As you can see the ping is working.

By now the load balancing on Layer2 will be working without any issue.

The last example that I wish to show you is Balance-rr. I will move the Bonding mode to Balance-rr and will do a Bandwidth-test and see the result. Remember on Balance Round Robin, one frame will be sent from one link and another one from another link.

Will start with SW1:

Will do the same on SW2

I will ping from SW2 to SW1 and see the result.

Now I will open BW test from SW2 to SW1 and see if the 2 links are being used at the same time.

Excellent, both links are fully used now. This is how you can increase your throughput on Layer2 using link aggregation.

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