During a network link congestion event, a network administrator notices that file transfer sessions automatically reduce their sending rate to prevent buffer overflows, while a concurrent real-time voice stream continues transmitting at a constant rate despite dropping packets. Which transport layer characteristic accounts for this difference in behavior?
- TCP utilizes sliding window mechanisms and acknowledgement tracking for dynamic flow control, whereas UDP lacks native flow and congestion control mechanisms.Answer
- BUDP relies on Layer 3 IP flags within its 8-byte header to perform rate limiting, whereas TCP uses Layer 2 Ethernet pause frames to signal congestion to the sender.
- CTCP relies on a smaller fixed 8-byte header that embeds explicit bandwidth regulation bits, whereas UDP uses a variable 20-byte header that omits timing control fields.
- DUDP buffers unacknowledged packets at the transport layer until missing sequence numbers arrive, whereas TCP drops corrupted packets without signaling retransmission.
Answer
TCP provides dynamic flow control and reliability through sliding windowing and acknowledgement tracking, whereas UDP is connectionless and lacks built-in flow or congestion control.
TCP is a stateful, connection-oriented protocol that features dynamic flow control mechanisms such as sliding windows and window size scaling. When network congestion occurs and packet loss is detected, TCP throttles its transmission window to adapt to path capacity. UDP is stateless and connectionless, possessing no mechanism for tracking delivered data or modifying sending rates in response to network congestion.
Step-by-Step Solution
Key Concept
TCP Connection-Oriented Flow Control vs UDP Connectionless Operation