To connect multiple LANs located in different cities using data links, there are several strategies you can use, depending on your specific requirements, budget, and infrastructure availability. Below I describe some of the most common options:

1. VPN (Virtual Private Network)

• IPsec VPN: Uses the IPsec protocol to encrypt traffic between two or more sites. It is compatible with most devices and provides a high level of security.

• openvpn: It is an open source VPN solution that supports various encryption methods. It is flexible and easily configurable to adapt to different needs.

• wire guard: It is a modern VPN that aims to be simpler, faster, and more secure. It is easy to set up and provides excellent performance.

VPNs are ideal for connecting LANs over the Internet securely. You can set up a VPN server in a central location and connect VPN clients from other cities.

2. MPLS (Multiprotocol Label Switching)

MPLS is a technique in which data packets are routed over a private network using short labels instead of long IP addresses. This allows the creation of “virtual tunnels” that are efficient and secure. MPLS is typically offered by Internet Service Providers (ISPs) as a private network solution.

3. Dedicated Links

Dedicated links, such as T1/E1 lines, direct fiber optics, or point-to-point radio links, offer private, high-capacity connections between sites. Although this option can be expensive, it provides the best performance and security since the infrastructure is exclusively used by your organization.

4. SD-WAN (Software Defined Wide Area Network)

SD-WAN is an emerging technology that uses software to control connectivity, management and services between data centers and remote offices. It allows the use of multiple connection types, such as MPLS, broadband, and LTE, to create a network over the Internet that is centrally managed.

Implementation with MikroTik

If you are using MikroTik equipment, you can implement several of these solutions:

• For VPN, MikroTik RouterOS supports IPsec, OpenVPN, and L2TP, among others. You can configure MikroTik routers to act as VPN servers or clients.
• For dedicated links, you can use MikroTik equipment that supports the necessary interfaces for your type of connection (for example, fiber optics or radio links).
• For SD-WANAlthough MikroTik does not offer its own SD-WAN solution, you can manually configure some of the functionality using scripts and advanced routing policies.

Choosing between these options will depend on your specific needs for performance, security, and budget.

In general, implementing a VPN over the Internet is the most cost-effective and quickest option to implement for most organizations, while solutions such as MPLS and dedicated links offer better performance and reliability at a higher cost.