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Questions and Answers
What is the primary function of a hub in a network?
What is the primary function of a hub in a network?
A hub connects multiple devices in a network and transmits data packets to all connected devices.
How does a bridge improve network efficiency compared to a hub?
How does a bridge improve network efficiency compared to a hub?
A bridge reduces collision domains by connecting multiple networks and filtering traffic, allowing only relevant data to pass through.
Explain the role of a switch in a local area network (LAN).
Explain the role of a switch in a local area network (LAN).
A switch intelligently forwards data to specific devices based on their MAC addresses, reducing unnecessary data transmission.
What is a VLAN, and why is it used in networking?
What is a VLAN, and why is it used in networking?
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What is the function of a Network Interface Card (NIC) in a computer?
What is the function of a Network Interface Card (NIC) in a computer?
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What happens when bridge α transmits a frame at time t1?
What happens when bridge α transmits a frame at time t1?
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How do bridges differ from repeaters in terms of network connectivity?
How do bridges differ from repeaters in terms of network connectivity?
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What is a key characteristic of a hub?
What is a key characteristic of a hub?
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What is the main difference between managed and unmanaged hubs?
What is the main difference between managed and unmanaged hubs?
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Describe how switches function within a network.
Describe how switches function within a network.
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What occurs when both bridges receive the frame from station A?
What occurs when both bridges receive the frame from station A?
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Why are wireless bridges important in networking?
Why are wireless bridges important in networking?
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How do bridges impact data transmission in a network?
How do bridges impact data transmission in a network?
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What is the primary function of a bridge in a network?
What is the primary function of a bridge in a network?
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Explain the difference between a store-and-forward switch and a cut-through switch.
Explain the difference between a store-and-forward switch and a cut-through switch.
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What are the two main functions that a bridge cannot perform?
What are the two main functions that a bridge cannot perform?
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How does a switch differ from a bridge in terms of frame handling?
How does a switch differ from a bridge in terms of frame handling?
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What is the significance of the Fiber Distributed Data Interface (FDDI) ring standard in networking?
What is the significance of the Fiber Distributed Data Interface (FDDI) ring standard in networking?
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Define Shannon's theorem related to data transmission.
Define Shannon's theorem related to data transmission.
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Distinguish between a managed hub and an unmanaged hub.
Distinguish between a managed hub and an unmanaged hub.
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What is the role of a repeater in network topology?
What is the role of a repeater in network topology?
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What role does a repeater play in a Local Area Network (LAN)?
What role does a repeater play in a Local Area Network (LAN)?
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How do bridges improve the performance of a LAN compared to repeaters?
How do bridges improve the performance of a LAN compared to repeaters?
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What characteristic defines a transparent bridge?
What characteristic defines a transparent bridge?
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What happens when a collision occurs in a network segment with a repeater?
What happens when a collision occurs in a network segment with a repeater?
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What is the primary function of a source-routing bridge?
What is the primary function of a source-routing bridge?
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Why are bridges generally preferred over repeaters in network design?
Why are bridges generally preferred over repeaters in network design?
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What happens to a data packet if its destination address is on the segment it was received from when processed by a transparent bridge?
What happens to a data packet if its destination address is on the segment it was received from when processed by a transparent bridge?
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In what way do bridges classify themselves based on how they operate?
In what way do bridges classify themselves based on how they operate?
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Study Notes
Module Information
- Module code: G51SYS
- Topic: Systems and Architecture
Objectives
- Discuss repeaters, bridges, hubs, and switches in a network
- Differentiate between two types of bridges
Repeaters
- Electrical signals weaken as they travel
- Repeaters join LANs to overcome signal weakness
- Continuously monitor electrical signals on each LAN
- Do not understand the difference between a valid frame and other electrical signals
- A collision/interference on one segment causes a repeater to recreate signals on the other segment (even overlapping signals)
Bridges
- Electronic devices that interconnect LAN segments
- Improve LAN performance by dividing the LAN into segments with a bridge between them
- Listen to traffic on each segment in promiscuous mode, forwarding all frames
- More popular than repeaters as they do not forward erroneous frames (like collisions or noise)
- Two LAN segments connected by a bridge behave like a single LAN
Transparent Bridges
- Require no initial programming (adaptive/learning bridge)
- Learn computer locations automatically after installation
- Learn locations of network devices by associating source addresses of incoming packets with the line they were received on
- Analyze data packets' destination addresses
- Discard packets if the destination is on the same segment as the source
- Forward packets if the destination is on a different segment
Source-Routing Bridge
- Entire route to the destination station is in the packet sent by the source
- Passes the packet to the next device in line as specified by the route in the packet
- The next device may be another bridge or the destination device
Learning Bridge
- Diagram of a learning bridge with addresses and ports
Loop Problem in Bridges (Example)
- Station A transmits a frame to station B, captured by both bridges
- Bridges update their databases to know stations are on LAN X and Y, retransmitting on LAN Y
- Bridge B receives two copies of the frame.
- Each bridge receives the other's transmission on LAN Y, the frame having a source address of A and a destination address of B
- Bridges update their databases, now unable to forward frames addressed to station A.
Bridges and LANs with Alternative Routes
- Diagram showing bridges connecting different LANs
Bridge and Repeater Comparison
- Bridges connect networks in different geographical locations requiring a telecommunication link
- Wireless bridges suitable for limited-distance remote connections
Hub
- Device that interconnects incoming data onto all outgoing connections
- Works at the physical layer
- Immediately forwards frames without examining or modifying their content
- Sends a copy of data from one workstation to all other workstations connected to the hub
Managed Hub vs. Unmanaged Hub
- Managed hub: sufficient processing power, manageable remotely, participates in network management operations
- Unmanaged hub: little or no intelligence, cannot be controlled remotely, cannot participate in network management operations, less expensive
Switches
- Combination of a hub and bridge
- Interconnects multiple workstations like a hub, but filters frames to segment the network
- Provides a significant decrease in interconnection traffic
- Increases throughput of interconnected networks without additional cabling or device rearrangements
Switch vs. Bridge
- Bridge: frame handled by software, analyzes and forwards one frame at a time, uses store-and-forward operation
- Switch: frame handled by hardware, handles multiple frames at a time, can have cut-through operation
Store-and-Forward Switch and Cut-Through Switch
- Store-and-forward switch: stores each incoming frame entirely, examines it, then forwards it.
- Cut-through switch: starts forwarding incoming frames before they arrive completely, forwards as soon as the destination address is in.
Layer of Operation
- Bridge/LAN switch operates in the Link layer
- Repeater/hub operates in the Physical layer
Bridging Between Buildings
- Diagram of a bridge connecting LAN segments in two buildings
- An optical fiber connects the bridge to a remote LAN segment.
Bridging Across Longer Distances
- Diagram of a bridge using a leased satellite channel to connect LAN segments
- A satellite bridge can span arbitrary distances.
Review Questions
- Explain the difference between transparent and source-routing bridges
- Explain the difference between managed and unmanaged hubs
- Describe the importance of the Fiber Distributed Data Interface (FDDI) ring standard
- State Shannon's theorem
Networking Hardware (additional slides)
- Diagrams illustrating hubs, repeaters, bridges, switches, VLANs, and NICs
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Description
Test your knowledge on systems and architecture with a focus on network devices like repeaters, bridges, hubs, and switches. This quiz will help you differentiate the functions of these devices and understand their impact on LAN performance. Prepare to explore key concepts for enhancing network efficiency.