This tutorial explains the concept of policy routing with a practical example. Policy routing is a feature which is available on routers and operating systems , which allows to forward packets based on the source IP address in the IP header. Normally, when a packet is received on a router, it looks into the destination IP address to make the forwarding decision.
In the above diagram there are two network, which are 192.168.1.0/24 and 192.168.2.0/24. The router also has two internet connections. It is required that all packets originating from 192.168.1.0/24 should be forwarded through one internet link and packets from 192.168.2.0/24 forwarded to the other link. In a typical environment, all internet bound packets originating from the LAN network can be forwarded to either one of the internet links. With the help of policy routing, packets originating from a specific source network address can be forwarded out through the required interface. The router can be configured with policy routing to achieve the stated requirement.
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