Is it advisable to use LAG + Mikrotik in this case?

Question

Computer networks

Before buying a router, I want to understand what capacity it makes sense to take a piece of iron.
Given:
- 3 gigabit managed switches Eltex 2124 ;
- the network is divided into several VLANs, each with about 20 machines + a guest in which I don’t even consider + 2 Internet;
- at the moment, a virtual machine with Kerio acts as a router + gateway.

There is a strong desire to abandon Kerio, tk. what I wanted to get from her does FIG knows how, in general, some frustrations, they didn’t buy the benefit.
As a replacement, it is supposed to take a Mikrotik router. But here the question arises of how to organize the connection, several options came to mind:
- we take a box for 4 ports, we start switches on it, there is no direct link between ourselves;
- we take a box for 4 ports, connect switches of 2 ports to the LAG, and in one of them we also connect a box through the LAG of two ports;
- we already take a rack version from Mikrotik 1100AH ​​with 12 gigabit ports and we start all the switches on it, each through 4 ports in the LAG.

I'm leaning towards the latter option. Is it advisable or can one of the first two be dispensed with?
Tasks for Mikrotik are actually routing, access to the Internet, VPN server and filtering.

Answer 1

What traffic (bps/pps) inside the network and out?
If small, then RB2011 is suitable.
If large - then CCR1016.
If the internal is large, the external is small, then it is better to have a separate routing switch in the core and a separate gateway on Mikrotik, for example, RB951.
In terms of topology, a star is better than a garland.

Answer 2

Another option is to install RouterOS on an x86 machine, and install a 4-port board(s). If you look to the future, and there is a reality that you will have switches with 10G ports, this option is the most acceptable, because you can also insert a 10G card (s) into the machine, RouterOS already supports a number of models, in particular from Intel . Yes, and performance will be better, given modern processors. And so is extensibility.

Answer 3

You can save on the last option and take MikroTik RB / 493GPI. Pretty good piece of iron.

Answer 4

I wonder how your search ended, and what you came to. I see that they asked for a long time, yes))
PS Mikrotik 1100AH ​​(more precisely, Mikrotik 1100AHx2, without x2 is no longer on sale) it’s not worth it, it doesn’t have a “flat field” of ports, but a pair of switches with 5 ports + two more, in different ways connected to the processor ( i.mt.lv/routerboard/files/Block-RB1100AHx2.pdf ). This is in my mind the most unfortunate scheme to create LAGs. On the other hand, traffic that requires 8 Gb / s links (4 in each direction) involuntarily makes you ask whether such a piece of iron is right for you, what you will do on it, and in general, is there any certainty that LAG is so good channels will balance in bundles, so that you will get a decent load of links at the output. Or is it just a matter of reliability?
Look towards new models with SFP + modules, where there will immediately be 10 Gb / s in each direction. True, the issue is in switches, not everyone knows how to SFP +, but on such traffic there should be a budget for switches ...