The “routing mark” option on routes is a powerful feature used in routing systems like MikroTik RouterOS.

It is used to create and manage multiple routing tables within the same device. This allows network administrators to implement advanced and specific routing policies, facilitating the segregation and efficient handling of network traffic.

Here are some of the main uses of the routing mark option:

Traffic Separation

Routing marking allows you to separate traffic on a network according to different criteria, such as origin, destination, or type of service.

This is particularly useful in complex networks where different types of traffic require specific treatments, such as separating VoIP traffic from web browsing traffic to ensure quality of service.

VPN implementation

In the context of VPNs (Virtual Private Networks), the routing mark option is essential to direct traffic to and from the VPN.

This allows network administrators to ensure that only traffic destined for the VPN passes through it, while regular traffic follows other routes.

Load balancing

Routing flag is also used to implement load balancing strategies between multiple Internet connections or between different network links. This is achieved by marking traffic to follow different routes based on specific rules, thus distributing the load more efficiently and increasing redundancy.

Rules-Based Routing Policies

By using routing marks, routing policies can be applied based on complex rules, which take into account various factors such as application types, specific users or traffic priorities. This offers great flexibility in managing how traffic is routed within a network.

Multi-Homing Implementation

Multi-homing, or the ability of a network to connect to the Internet through multiple service providers, can be managed effectively with the help of routing marks.

Each provider can have its own routing table marked, enabling intelligent routing decisions that can improve availability and performance.

Practical Example in RouterOS

In MikroTik RouterOS, configuring a route with a specific routing flag could involve defining mangle rules in the firewall to mark packets based on certain criteria, and then creating routes that specify that marked packets should follow a certain path.

This is often done in combination with features such as policy routing to effectively route traffic across multiple interfaces or Internet connections based on assigned branding.

In summary, the routing mark option is an essential tool in the network management toolbox, providing the ability to manage traffic granularly and effectively to meet specific network performance, security and efficiency requirements.