You are connecting a legacy IPX/SPX network to an IP network. Which of the following is the most appropriate device? (Wentz QOTD)
A. Brouter
B. Gateway
C. Layer 3 switch
D. Next-generation firewall

Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.

My suggested answer is B. Gateway.

Wentz’s book, The Effective CISSP: Security and Risk Management, helps CISSP and CISM aspirants build a solid conceptual security model. It is a tutorial for information security and a supplement to the official study guides for the CISSP and CISM exams and an informative reference for security professionals.

A network connects two or more nodes through transmission media to share resources; it has two architectural views: physical and logical. The logical portion of a network works on top of the physical. A logical network is represented by network layer protocols, e.g., IP. The IP protocol numbers (addresses) nodes and networks using 32-bit IP addresses and subnet masks. All networks that execute the same protocol are homogeneous. A mixture of IP networks and IPX networks is heterogeneous. A router typically connects homogeneous logical networks. A gateway in this context refers to a device that connects homogeneous networks, which typically entails protocol transformation. A firewall aims to filter packets or screen messages. A next-generation firewall emphasizes nothing but the idea that it handles more and more emerging requirements and provides more solutions.

Signal and Repeater

A physical network is the underlying infrastructure of a logical network. The primary physical elements are transmission media and the signal that carries data. How long a signal can travel over the media varies; no matter which media is used, the signal always attenuates. The analog signal is amplified by an amplifier, while the digital signal is repeated by a repeater so that they can travel farther before they diminish.

Topology and Bridge

Nodes are connected by transmission media, either wired or wireless, and that formulates a shape or topology. Linear bus, circular ring, hierarchical tree, and mesh network are common topologies. A bridge connects two or more networks in different shapes or topologies.

Data Link Layer: MAC and LLC

Nodes on a network in any shape/topology can communicate with each other just like any pair of them are directly linked through a cable. In fact, those nodes share the same media. In other words, they are linked logically instead of physically. We call the communication between any pair of nodes on a network a logical link. The rules for the nodes connected by the shared media is called media access control (MAC); error and flow control between any pair of nodes on a network is called logical link control (LLC). MAC and LLC are collectively treated as major concerns of the data link layer in the ISO OSI reference model.

Reference

• Repeaters, Bridges, Routers, And Gateways: A Comparative Study
• Explain in detail repeater, hub, bridges, routers, gateway, switches.
• Next-generation firewall

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您想將一個舊式的IPX/SPX網路連接到IP網路。 以下哪一項是最適合的設備？ (Wentz QOTD)
A. Brouter
B. Gateway
C. Layer 3 switch
D. Next-generation firewall