Which feature is used to route traffic to a specified ISP based on the source address?

The feature that is used to route traffic to a specified Internet Service Provider (ISP) based on the source address is known as filter-based forwarding. This approach allows the router to make forwarding decisions based on criteria defined in a firewall filter, such as the source or destination address of the traffic. By applying these filters, the network administrator can control which ISP is chosen for outgoing traffic depending on the source of that traffic, thus enabling more granular control and traffic management.

Filter-based forwarding is particularly useful in scenarios where different source addresses or ranges are associated with different ISPs, allowing for policies that cater to specific bandwidth allocations, routing preferences, or cost efficiencies.

The other options, while related to routing and traffic management, do not specifically address the routing of traffic based on the source address in the same way that filter-based forwarding does. For example, BGP outbound policy is more about managing BGP routes and preferences among multiple paths or ISPs rather than dealing with source-based decision-making. Local preference also deals with choosing preferred paths within BGP but pertains to the internal routing environment rather than affecting routing decisions based on source addresses. IP source routing allows a packet's sender to specify the route the packet should take, but it is not a feature implemented at the