https://songkou.github.io/tags/tcp/Recent content in TCP on Council of ElrondHugoenThu, 16 Jul 2026 00:00:00 +0800https://songkou.github.io/posts/tcp_three_way_handshake_and_four_way_termination/Thu, 16 Jul 2026 00:00:00 +0800https://songkou.github.io/posts/tcp_three_way_handshake_and_four_way_termination/<blockquote> <p>Study notes rewritten in English.</p> </blockquote> <h2 id="tcp-basics">TCP basics</h2> <h3 id="what-is-tcp">What is TCP?</h3> <p>TCP is a <strong>connection-oriented</strong>, <strong>reliable</strong>, <strong>byte-stream</strong> transport-layer protocol.</p> <ul> <li><strong>Connection-oriented</strong> – strictly one-to-one. Unlike UDP, one host cannot broadcast to many hosts over a single TCP connection.</li> <li><strong>Reliable</strong> – no matter what happens on the link, TCP guarantees a segment eventually reaches the receiver.</li> <li><strong>Byte stream</strong> – the OS may split a user message into several TCP segments. Segments are ordered: if the previous segment hasn&rsquo;t arrived, a later one that did arrive cannot be handed up yet; duplicate segments are dropped.</li> </ul> <p>IP is <strong>unreliable</strong> — it doesn&rsquo;t guarantee delivery, ordering, or integrity. If you need reliability, the transport-layer TCP has to provide it.</p>