routingregler

Routingregler, in networking, refers to a set of rules that determine how packets are forwarded within a network or by a host. They complement traditional routing protocols by allowing administrators to influence path selection based on criteria beyond the destination address, such as source address, protocol, or traffic class. The term is used in various languages to denote routing rules or policy-based routing.

A routingregel typically consists of match criteria and corresponding actions. Match criteria specify conditions such as source or destination IP, port numbers, protocol, or traffic type. Actions define what happens when a rule matches, for example selecting a specific routing table, overriding the next-hop, directing traffic through a VPN or tunnel, or dropping the packet. Rules are evaluated in a defined order, and the first matching rule usually determines the fate of the packet. Routingregler can reference multiple routing tables or routing policies to achieve flexible traffic steering.

Common implementations include policy-based routing on routers, where route-maps or route-policies influence next-hop selection or route attributes, and host-based routing, where operating systems use mechanisms like Linux IP rule and separate routing tables to steer traffic based on source addresses or other criteria. In Linux, for example, administrators can create multiple routing tables and attach rules that select a table based on the packet’s source address, then provide routes in those tables.

Applications of routingregler include traffic engineering in multi-homed networks, load balancing across multiple links, enforcing security or compliance policies by directing certain traffic through designated paths, and testing or experimenting with alternative routing scenarios. They are typically used in conjunction with, rather than as a replacement for, dynamic routing protocols.