Suggest an editImprove this articleRefine the answer for “What is a protocol stack?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)A **protocol stack** is a set of network protocols that work together in layers, ensuring data transmission from an application on one device to an application on another. **Key point:** each protocol operates at its own layer, uses the services of the layer below, and provides services to the layer above.Shown above the full answer for quick recall.Answer (EN)ImageA **protocol stack** is a *set of network protocols that work together in layers*, ensuring data transmission from an application on one device to an application on another. Short formulation for an interview: > **A protocol stack is a collection of interconnected protocols operating at different layers of a model (for example, TCP, IP, HTTP) that together provide network interaction.** Protocols form a "stack" because: - each protocol operates **at its own layer** - each uses the services **of the layer below** - and provides services **to the layer above** --- ## **How a protocol stack is structured** The stack works on the principle of a *layered cake*: ``` Application → TCP/UDP → IP → Ethernet → physical transmission ``` Each layer: - receives data from the layer above - adds its own headers (encapsulation) - passes it down On the receiving side, everything happens in reverse - the data is "unwrapped". --- ## Example of the most well-known stack - **TCP/IP** The TCP/IP stack consists, for example, of: **Application layer** - HTTP, HTTPS, DNS, SMTP, FTP, DHCP ↓ **Transport layer** - TCP, UDP ↓ **Internet layer** - IP, ICMP ↓ **Data link layer** - Ethernet, Wi-Fi, PPP All these protocols together make the internet work. --- ## **Why a protocol stack is needed** The stack allows you to: #### standardize device interaction So that computers from different manufacturers can work together. #### separate tasks Each layer handles its own part: - application - logic - transport - delivery - network - routing - link - frames - physical - signals #### simplify development An HTTP developer doesn't need to think about MAC addresses - the layer below handles that. #### ensure modularity You can replace one protocol without breaking the whole stack (for example, IPv4 → IPv6). --- ## **A protocol stack ≠ a single protocol** It is important: **a stack is not one protocol**, but a *collection* of protocols working together. For example: - TCP - transport - IP - network - Ethernet - link - ARP - auxiliary - ICMP - diagnostics - HTTP - application All together - the **TCP/IP stack**. --- ## Other examples of protocol stacks - **OSI (theoretical)** - 7 layers - **Bluetooth stack** (L2CAP, SDP, RFCOMM) - **VoIP stack** (SIP, RTP, RTCP) - **5G/4G stack** - dozens of layers of mobile protocols --- ## **Ready answer for an interview** > **A protocol stack is a set of interacting protocols organized by layers.** > **Each protocol plays its own role and uses the functions of the layers below.** > **The best-known example is the TCP/IP stack, which includes HTTP/HTTPS, TCP/UDP, IP, ICMP, Ethernet, and other protocols.**For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.