PIO

/piː-aɪ-oʊ/

n. “A method for transferring data between the CPU and a storage device using programmed instructions rather than direct memory access.”

CWR

/siː-dʌbəl-juː-ɑːr/

n. “A TCP header flag used to indicate that congestion has been acknowledged and the sender can resume normal transmission.”

ECN

/iː-siː-ɛn/

n. “A mechanism in TCP/IP networks for signaling congestion without dropping packets.”

ECN, short for Explicit Congestion Notification, is a feature of modern IP networks that allows routers and endpoints to signal network congestion to senders proactively. Instead of relying solely on packet loss to indicate congestion, ECN marks packets to alert the sender to slow down, improving network efficiency and reducing latency.

URG

/ɜːr-dʒ/

n. “A TCP control flag indicating that certain data should be treated as urgent.”

In the context of the Transmission Control Protocol (TCP), URG (short for urgent) is a flag used to indicate that some of the transmitted data in a segment is urgent and should be prioritized by the receiving application. The flag works alongside the Urgent Pointer field in the TCP header to specify the position in the data stream where the urgent data ends.

Key characteristics of URG include:

PSH

/pʃ/

n. “A TCP control flag that instructs the receiving end to push buffered data to the application immediately.”

In the context of the Transmission Control Protocol (TCP), PSH (short for push) is a flag used to signal that the data being sent should be delivered to the receiving application immediately, without waiting to fill the buffer. This helps reduce latency for time-sensitive communication, ensuring data reaches the application as soon as possible.

Key characteristics of PSH include:

FIN

/fɪn/

n. “A control flag in TCP indicating the sender has finished sending data.”

In the context of the Transmission Control Protocol (TCP), FIN (short for finish) is a flag used to signal the termination of a TCP connection. When a device sends a FIN packet, it indicates that it has no more data to transmit, initiating the connection teardown process while allowing any remaining data to be received.

PPP

/ˌpiː-piː-ˈpiː/

n. “The protocol that wraps network packets for point-to-point links.”

PPP, short for Point-to-Point Protocol, is a data link layer protocol used to establish direct connections between two networked devices over serial links, telephone lines, or other point-to-point connections. It encapsulates network layer packets (like IP) into frames for transmission and provides features like authentication, compression, and error detection.

Key characteristics of PPP include:

SYN-ACK

/sɪn-æk/

n. “The TCP handshake’s polite ‘hello back’.”

SYN-ACK is a flag combination in the TCP (Transmission Control Protocol) header used during the three-way handshake to establish a reliable connection between two devices. It signals both synchronization and acknowledgment: the server acknowledges receipt of the client’s initial SYN request and simultaneously sends its own SYN to start communication in the opposite direction.

Key characteristics of SYN-ACK include:

NAK

/næk/

n. “The TCP or protocol signal that says ‘Nope, try again.’”

NAK, short for Negative Acknowledgment, is a control signal used in networking and communication protocols to indicate that a data packet or message was not received correctly or could not be processed. Unlike ACK, which confirms successful receipt, NAK tells the sender that the transmitted data needs to be retransmitted.

Key characteristics of NAK include: