How to build a fault-tolerant network?

Question

DHCP

Welcome all. At the moment, in our organization, the network is managed through Mikrotik, where addresses are distributed via DHCP if the mac address is in the userman database. The database is stored on an external HDD connected to Mikrotik. There is no backup Mikrotik. There is no fault tolerance, respectively. If Mikrotik is not available, then there is no local network or internet. Communication with other buildings goes through l2tp vpn. There are also Mikrotiks. I didn't build the network. I want to change the network.
I have an idea to switch back to DHCP from Windows in LAN failover in the form of "hot swap". And I have a few questions.
1. Will it be possible to configure NAT on Mikrotik if it does not manage DHCP now?
2. How can I distribute IP addresses on Windows DHCP so that it distributes an IP address if there is a MAC address in the conditional database? To prevent unknown devices from entering the network.
3. In the future, we want to change Mikrotik to Cisco. What models can you recommend? The budget for the router is from 40 thousand rubles to 100 thousand rubles. We also want to change the switches to Cisco. Stand D-Link. We also want Cisco. The budget for one switch is from 30 thousand rubles to 60 thousand rubles. What models can you recommend?

Answer 1

1. You can, these things are connected, but independent
2. You can reserve addresses, but protection from the left devices on the network is not done this way.
3. cisco 2960X are great machines for aggregation, they just work. But your budget is enough, alas, only for mikrotiki and PC with pfsense as a router.
If you have a network on a vend, your problem is solved by setting up at least two domain controllers - and you will have the fault tolerance you want.

Answer 2

What Cisco features are not in these pieces of iron https://mikrotik.com/products/group/switches
Which ones do you need?
Does your head office use CISCO?
What type of firm? State office, private, NPO?

Answer 3

1. Will it be possible to configure NAT on Mikrotik if it does not manage DHCP now?

Yes. DHCP only gives out network settings (ip/mask/default gateway/DNS server). it doesn't matter which server does it.
Make it easier. Give all unknown addresses IP addresses from a pool of addresses that has no access anywhere. And on the poppy address to issue specific IP addresses, with access. You can even issue different subnets.