Which of the following devices takes data sent from one network device and forwards it to the destination node based on MAC address?
Switch
Understanding Network Device Data Forwarding
The question asks about a network device that receives data from one device on a network and sends it specifically to the intended destination device using its MAC address. This process is known as forwarding based on the Data Link Layer address, which is the MAC address.
Analyzing Network Devices and Data Forwarding
Let's look at the options provided and how they handle data forwarding:
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Hub: A hub is a very basic network device that operates at the Physical Layer (Layer 1). When a hub receives data on one port, it simply broadcasts that data out to all other connected ports. It does not read MAC addresses or make any intelligent forwarding decisions. Every device connected to the hub receives the data, and the actual destination device processes it, while others discard it. This creates unnecessary network traffic.
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Modem: A modem (Modulator-Demodulator) is primarily used to convert digital signals from a computer into analog signals for transmission over lines like telephone or cable, and vice-versa. It acts as a bridge between a local network (like your home network) and a wide area network (WAN), typically the internet service provider's network. While it connects networks, its primary function isn't forwarding data within a local network based on MAC addresses.
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Switch: A switch is a network device that operates primarily at the Data Link Layer (Layer 2). When a switch receives data, it examines the destination MAC address in the data packet. It maintains a table, often called a MAC address table or CAM table, which maps MAC addresses to the physical ports on the switch. Using this table, the switch forwards the data only to the specific port where the destination device is connected. This directed forwarding significantly reduces network traffic compared to a hub.
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Gateway: A gateway is a device that acts as an entry and exit point for a network. It is often used to connect networks that use different protocols. A common example is a router, which connects your local network to the internet. Routers primarily operate at the Network Layer (Layer 3) and forward data based on IP addresses, not MAC addresses, when routing data between different networks.
Identifying the Device Using MAC Addresses for Forwarding
Based on the analysis, the device that specifically uses the MAC address to forward data to the correct destination node within the same network segment is the switch.
Here's a simple comparison of how hubs and switches handle traffic:
| Feature | Hub | Switch |
|---|---|---|
| Operating Layer | Physical Layer (Layer 1) | Data Link Layer (Layer 2) |
| Forwarding Method | Broadcasts to all ports | Unicasts (directs) to specific port based on MAC address |
| Intelligence | None (passive device) | Uses MAC table for intelligent forwarding |
| Network Traffic | High (collisions possible) | Lower (reduces collisions and congestion) |
| Performance | Lower | Higher |
Therefore, the device described, which forwards data based on the destination node's MAC address, is the switch.
Revision Table: Network Device Functions
| Device Type | Primary Function | Layer of Operation | Forwarding Basis |
|---|---|---|---|
| Hub | Connects devices, broadcasts data | Layer 1 (Physical) | None (Broadcasts all) |
| Modem | Modulate/Demodulate signals, connect to WAN | Layer 1/2/3 depending on functionality | Signal Conversion/Routing |
| Switch | Connects devices, intelligent forwarding within LAN | Layer 2 (Data Link) | MAC Address |
| Gateway (e.g., Router) | Connects different networks | Layer 3 (Network) | IP Address |
Additional Information: MAC Addresses and Network Layers
The MAC (Media Access Control) address is a unique identifier assigned to the network interface card (NIC) of a device. It is a Layer 2 address, used for delivery of data frames within the same local network segment (like within a single LAN). When data needs to travel outside the local network, Layer 3 addresses (IP addresses) are used for routing, and the MAC addresses change at each hop (router) along the path.
Understanding which layer a network device operates at helps explain its function:
- Layer 1 (Physical): Deals with the physical transmission of data (cables, signals). Devices: Hubs, repeaters.
- Layer 2 (Data Link): Deals with framing, MAC addresses, and local delivery of data. Devices: Switches, network interface cards (NICs).
- Layer 3 (Network): Deals with logical addressing (IP addresses) and routing data between different networks. Devices: Routers.
Switches play a crucial role in modern LANs by enabling efficient communication between devices using their MAC addresses.
Important Questions from Data Link Layer
Which of the following protocols is responsible for converting higher level protocol addresses to physical network addresses?
Which of the following statements is/are true with regard to various layers in the Internet stack?
P: At the data link layer, a packet of transmitted information is called a frame
Q: At the network layer, a packet of transmitted information is called a segment
Given below are two statements:
Statement I: The laws of nature put two fundamental limits on data rate of a channel. The H.Nyquist limit restricts the number of independent samples per second to twice the band-width in a Noiseless channel.
Statement II: Shannon's major result about noised channel is that maximum data rate of a channel whose band width is H Hz, and whose signal-to-noise ratio is S/N is given by:
Maximum number of bits/sec \(= H \;log_2 \left(1+\frac{S}{N}\right)\) is given by:
In the light of the above statements. choose the correct answer from the options given below
Which of the following statements are true?
(a) Three broad categories of Networks are:
(i) Circuit Switched Networks
(ii) Packet Switched Networks
(iii) Message Switched Networks
(b) Circuit Switched Network resources need not be reserved during the set up phase.
(c) In packet switching there is no resource allocation for packets.The sender window size to get the maximum efficiency is
