What is an 'Intermediate System' (IS) router's primary function?

An Intermediate System (IS) router's primary function is to receive packets and forward them to at least one other router. This is essential for the operation of a network because IS routers facilitate the transfer of data between different network segments or domains. In the context of the OSI model and particularly in the Intermediate System to Intermediate System (IS-IS) routing protocol, these routers handle data packets as they traverse the network, ensuring that data can be correctly forwarded based on the destination address.

IS routers operate within a larger context of routing, where they make decisions based on the routing tables they maintain and the protocols they use to communicate with other routers. Their ability to forward packets ensures that data can travel across various paths in complex networks, allowing for redundancy and efficient data delivery.

The other options do not capture the primary function of an IS router. While connecting different networks is a broader networking goal, the specific role of forwarding packets to other routers encapsulates the core activity performed by Intermediate System routers in facilitating network communication. Additionally, while IS routers may contribute to network security in some contexts, acting as a firewall is a distinct function that is not inherently a primary role of routers in the IS-IS framework. Storing routing tables is a part of the overall