Data Link Layer Issues1 Flashcards
What are circuit-switched networks?
Circuit-switched networks establish a dedicated end-to-end connection before communication begins. They provide reliable, consistent connections for real-time communication but waste bandwidth when idle and are inefficient for sporadic transmissions.
What are packet-switched networks?
Packet-switched networks divide data into packets that are forwarded individually. Routers determine the next hop for each packet. They are efficient for intermittent communication, but packets may arrive out of order and require reassembly.
What is Virtual Circuit Switching?
Virtual Circuit Switching creates a “virtual circuit” between the source and destination, where all packets follow the same path. It offers faster routing, smaller headers, and in-order packet arrival but is time-consuming to establish and not suitable for infrequent communication.
What is Datagram Switching?
Datagram Switching routes each packet independently. It is ideal for infrequent communication, offers load balancing through dynamic rerouting, but may result in out-of-order packets and high overhead for routing and headers.
What is contention in multiple access strategies?
Contention occurs when nodes send packets whenever they are ready, leading to frequent collisions. Collisions result in retransmissions, wasting bandwidth.
What is Carrier Sensing (CSMA)?
CSMA involves nodes testing the medium for a signal before transmitting. It reduces collisions compared to contention-based systems but can still result in collisions if multiple nodes transmit simultaneously.
What is Token Passing in multiple access strategies?
Token Passing involves a token circulating through the network, granting transmission rights to the holder. It eliminates collisions, maximizing bandwidth efficiency but requires more complex hardware and bandwidth for token management.
What is a Token Bus Network?
A Token Bus Network is a logical ring where the token is passed in a predefined sequence, commonly used in IEEE 802.4 networks with coaxial cables.
What is a Token Ring Network?
A Token Ring Network is a physical loop where nodes pass the token sequentially, ensuring reliable and collision-free communication. However, node or link failures can disrupt the entire network.
What is Star Topology in LANs?
Star Topology involves nodes connecting to a central hub, which manages communication. It is simple and resilient to node failures but a hub failure disrupts the entire network.
What is Ethernet?
Ethernet uses CSMA/CD for medium access and collision detection. It supports broadcasting for message delivery, and its frames include preambles, addresses, frame type, data, and error checks.
What is Fast Ethernet?
Fast Ethernet operates at 100 Mbps using Cat5 cabling (IEEE 802.3u) and supports 10/100 Mbps compatibility for gradual network upgrades.
What is Gigabit Ethernet?
Gigabit Ethernet operates at 1000 Mbps using Cat5e or optical fiber (IEEE 802.3ab/802.3z), suitable for high-speed LANs and WAN backbones.
What are Wireless LANs (WLANs)?
WLANs use wireless access points (WAPs) as shared communication hubs, with common standards including 802.11a/g (54 Mbps) and 802.11b (11 Mbps). They use RTS/CTS mechanisms to avoid collisions.
What are Ad Hoc Networks?
Ad Hoc Networks are small networks without WAPs, where hosts communicate directly without central management.
What is Flow Control in Data Link Layer?
Flow Control limits the packet rate to prevent overwhelming the source or destination.
What is Error Control in Data Link Layer?
Error Control detects and retransmits corrupted packets using techniques like checksums and CRC (Cyclic Redundancy Check).
What are MAC Addresses?
MAC (Media Access Control) addresses are 48-bit globally unique identifiers for network interface cards (NICs), used for local delivery within a single LAN.
What is FDDI (Fiber Distributed Data Interface)?
FDDI is a high-speed optical token-ring network that is immune to electromagnetic interference, supports long distances and high-speed data (100 Mbps), and ensures reliability through a dual-ring topology.
