Highest Layer of OSI Model for Router ACL Operation

A network technician is configuring network addresses and port numbers for a router ACL to block a peer-to-peer application.

Which of the following is the HIGHEST layer of the OSI model at which this router ACL operates?

A.

Transport

B.

Network

C.

Session

D.

Application.

A.

The OSI model is a conceptual framework used to describe how data is transmitted over a network. The model is divided into seven layers, each of which performs specific functions related to the transmission of data.

In this scenario, the network technician is configuring a router access control list (ACL) to block a peer-to-peer application. An ACL is a list of rules that determine which traffic is allowed to pass through a network device, such as a router.

The layer of the OSI model at which the router ACL operates is determined by the type of information it examines.

Transport layer (Option A) is responsible for ensuring reliable data delivery between two endpoints, such as the TCP or UDP protocols. However, a router ACL is not concerned with the reliability of data delivery and does not operate at the transport layer.

Network layer (Option B) is responsible for routing data packets between networks, such as IP or ICMP protocols. A router ACL operates at the network layer since it examines IP packet headers to determine whether to allow or block traffic.

Session layer (Option C) is responsible for establishing and managing communication sessions between applications. However, a router ACL is not concerned with session establishment and does not operate at the session layer.

Application layer (Option D) is responsible for providing services to applications, such as HTTP, FTP, or SMTP. A router ACL does not operate at the application layer since it does not examine the payload of application data.

Therefore, the highest layer of the OSI model at which this router ACL operates is the network layer (Option B).