Concept Exercise Chapter 6 Name:
Date: Class:
Cisco Exercises - Semester 1 - Networking Fundamentals
Chapter 6 Layer 2: Concepts
Introduction
All data sent out on a network is from a source and is going to a destination. After data is transmitted, the data link layer of the OSI model provides access to the networking media and physical transmission across the media, which enables the data to locate its intended destination on a network. In addition, the data link layer handles error notification, network topology, and flow control. If you refer to the OSI model, you will see that the data link layer is adjacent to the physical layer. The data link layer provides reliable transit of data across a physical link. This layer uses Media Access Control (MAC) addresses. In so doing, the data link layer is concerned with physical (as opposed to network, or logical) addressing, network topology, line discipline (how end systems will use the network link), error notification, ordered delivery of frames, and flow control. Moreover, the data link layer uses the MAC address to define a hardware or data link address in order for multiple stations to share the same medium and still uniquely identify each other. Before a data packet is exchanged with a directly connected device on the same LAN, the sending device needs to have a MAC address it can use as a destination address.
Concept Questions
Demonstrate your knowledge of these concepts by answering the following questions in the space provided.
Every computer, whether it is attached to a network or not, has a unique physical address; no two physical addresses are ever alike. How is this achieved?
The AMC address, or the physical address, is located on a network interface card (NIC). Thus, on a network, the NIC is where a device connects to the media.
Each NIC, which is located in the data link layer of the OSI reference model, has a unique MAC address.
On a network, when one device wants to send data to another device, it can open a communication pathway to the other device by using the other device's MAC address. How is this done?
When data is sent out on a network by a source, it carries the MAC address of its intended destination. Does it carry the address of the source?
As this data travels along the networking media, the NIC in each device on the network checks whether its MAC address matches the physical destination address carried by the data packet.