RouterOS routing information consists of two main parts:
Routing Information Base is a database that lists entries for particular network destinations and their gateways (address of the next device along the path or simply nexthop). One such entry in routing table is called route.
By default all routes are organized in one "main" routing table. It is possible to make more than one routing table which we will discuss further in this article, but for now for sake of simplicity we will consider that there is only one "main" routing table
RIB routing table contains complete routing information, including static routes and policy routing rules configured by the user, routing information learned from dynamic routing protocols (RIP, OSPF, BGP) and information about connected networks.
Its purpose is not just to store routes, but also to filter routing information, to calculate best route for each destination prefix, to build and update Forwarding Information Base and to distribute routes between different routing protocols.
Connected routes are created automatically for each IP network that has at least one enabled interface attached to it (as specified in the /ip address or /ipv6 address configuration). RIB tracks status of connected routes, but does not modify them. For each connected route there is one IP address item such that:
Preferred source is not used any more for connected routes. FIB chooses source address based on out-interface. This allows to make setups that in ROS v6 and older were considered invalid. See examples for more details. |