Ethernet and LAN Protocols Quiz

LAN Technologies

• LAN technologies encompass various standards for local area networks.
• LAN operations are categorized into contention and controlled access methods.
• IEEE 802 standards define various LAN technologies.
• Examples of IEEE standards include Ethernet (802.3), Token Bus (802.4), Token Ring (802.5), and DQDB (802.6).
• FDDI is another controlled access method, an ANSI/ITU-T standard.
• Network Interface Cards (NICs) are essential components for connecting devices to the network.

Lecture Objective

• Understand LAN operations.
• Learn IEEE LAN standards.
• Explore Token Ring and FDDI operations.
• Understand Network Interface Cards (NICs).

LAN Standards

• Ethernet (IEEE 802.3) is a contention-based standard.
• Token Bus (IEEE 802.4) is a controlled access standard.
• Token Ring (IEEE 802.5) is another controlled access standard.
• DQDB (IEEE 802.6) is a distributed queue dual bus standard.
• Standards specify categories: contention (e.g., Ethernet) or controlled access (e.g., Token Ring).
• FDDI is an ANSI/ITU-T controlled access standard.

Persistence Algorithms

• Non-persistent CSMA uses random delays to minimize collisions.
• If medium is idle, transmit the packet. If busy, wait for a random amount of time from the probability distribution, then retry.
• 1-persistent CSMA transmits immediately if the medium is idle. Otherwise, it waits until idle and transmits immediately.
• P-persistent CSMA is a compromise between non-persistent and 1-persistent. The decision to transmit or wait a period is probabilistic.

Non-persistent CSMA

• Rules for non-persistent CSMA include transmitting if medium is idle and waiting a random amount of time if medium is busy, then retrying.
• Random delays in this protocol reduce the probability of collisions.
• Some capacity is wasted because the medium may remain idle after a transmission ends.
• Non-persistent stations are deferential, giving preference to others.

1-persistent CSMA

• 1-persistent CSMA avoids idle channel time, transmitting immediately if the medium is idle.
• Wait until the medium is idle if busy, then transmit immediately.
• This protocol is considered "selfish" because it transmits at every opportunity..
• Multiple stations waiting to transmit may cause collision.

P-persistent CSMA

• This algorithm is a balance between collisions and idle time.
• If idle, transmit with a certain probability (p).
• Wait for a time unit, otherwise.
• If busy, listen until idle, and repeat step 1
• Managing the probability 'p' effectively is crucial to minimizing collisions.

Which Persistence Algorithm?

• IEEE 802.3 (Ethernet) uses the 1-persistent algorithm.
• Both non-persistent and p-persistent CSMA have their performance problems.
• 1-persistent is unstable due to high collision rate because stations are greedy..
• P-persistent is better as wasted time due to collisions is shorter, and stations are less likely to collide on the next attempt given random backoff.

Categories of Standard Ethernet

• 10Base5 (thick Ethernet), a bus topology, with thick coaxial cable & external transceiver.
• 10Base2 (thin Ethernet), a bus topology, with thinner, flexible coaxial cable.
• 10Base-T (twisted-pair Ethernet), a star topology, uses twisted-pair cable.
• 10Base-F (fiber Ethernet), a star topology, uses fiber optic cable.

10 Base 5: Thick Ethernet

• Used a thick coaxial cable that formed a bus topology.
• Required an external transceiver which connected via a tap to the cable.
• A maximum length of 500 meters and ran at 10 Mbps.

10 Base 2: Thin Ethernet

• Cheapernet- is a more flexible thin coaxial cable.
• It also used a bus topology.
• A maximum length of 185 meters and 10 Mbps, but is lower in cost compared to 10Base5.

10Base-T and 10Base-F

• 10Base-T uses twisted-pair cabling,
• 10Base-F uses Fiber optic cabling,
• Both use a star topology, with a central hub or switch.

Fast Ethernet

• IEEE defined Fast Ethernet under the name 802.3ae.
• This is a higher speed protocol (100Mbps).
• Various implementations exist (100Base-TX - category 5 UTP cable, 100Base-FX - Fiber).

Fiber Distributed Data Interface -FDDI (802.6)

• A token-ring-like network standard using optical fiber.
• It runs at a 100Mbps data rate.
• Implemented as a dual ring.
• The primary ring carries data; the secondary acts as a backup in case the primary fails.

Fibre Channel Applications

• Used for linking high-performance workstations, connecting mainframes, linking LANs and WANs to the backbone, and clustering disk farms.

Advantages and disadvantages of FDDI

• Advantages: high bandwidth (250Gbps), supports a large number of terminals (up to 1000 for 200km). high resistance to EMI.
• Disadvantages: costly, requires significant expertise for installation and maintenance.

LAN Wiring and Physical Topology

• This subject matter covers physical wiring configurations for local area networks (LANs).

Network Interface Card

• Internal NICs plug into the computer's motherboard expansion slot..
• PCI (Peripheral Component Interconnect) is one type of motherboard slot used for internal NICs.

Network Interface Hardware

• NICs are special purpose hardware which receive and send data over a network.
• Most NICs use DMA to process data without CPU intervention.

NIC support all three kinds of connections

Review Questions

• Questions about tokens, CSMA, CSMA/CD, Ethernet frames, different CSMA/CD protocols, binary exponential backoff, token ring networks, and Shannon's theorem.

Reference

• Lists the textbooks used for the study materials.

Test your knowledge on Ethernet networks and LAN protocols with this quiz. Explore critical concepts such as CSMA protocols, Ethernet standards, and the structure of FDDI. Perfect for students and professionals looking to reinforce their understanding of networking technology.