Stories with Tag TCP

• What would happen if we didn't use TCP or UDP?

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  Posted: 2025-02-25 07:13:23

  Verbose tl;dr

  Without TCP or UDP, internet communication as we know it would cease to function. Applications wouldn't have standardized ways to send and receive data over IP. We'd lose reliability (guaranteed delivery, in-order packets) provided by TCP, and the speed and simplicity offered by UDP. Developers would have to implement custom protocols for each application, leading to immense complexity, incompatibility, and a much less efficient and robust internet. Essentially, we'd regress to a pre-internet state for networked applications, with ad-hoc solutions and significantly reduced interoperability.

  The hypothetical scenario of a world without TCP or UDP, the two dominant transport layer protocols of the internet protocol suite, would drastically reshape how networked communication functions. The post explores the potential consequences and alternatives, emphasizing the crucial role these protocols play in ensuring reliable and efficient data transmission.

  Without TCP and UDP, the fundamental mechanisms for establishing connections, managing data flow, and ensuring data integrity would be absent. Applications relying on these features would cease to function as intended. This includes the vast majority of internet services we use daily: web browsing (HTTP/HTTPS), email (SMTP), file transfer (FTP), and real-time communication (VoIP, video streaming). These services depend on the guarantees provided by TCP and UDP, whether it be the ordered, reliable delivery of TCP or the connectionless, speed-prioritizing nature of UDP. Their absence would necessitate entirely new protocols or radical adaptations to existing application-layer protocols.

  The post outlines potential alternatives, including the possibility of applications implementing their own custom transport layer functionalities. This implies each application would need to handle tasks like segmentation, reassembly, error detection, and flow control individually. This approach would lead to significant redundancy, increased complexity in application development, and potential inconsistencies in how data is handled across different applications. It also raises concerns about interoperability, as applications using different custom transport mechanisms might struggle to communicate effectively.

  Furthermore, the post highlights the potential for operating systems to absorb some of the responsibilities currently handled by TCP and UDP. This could involve the OS providing basic segmentation and reassembly services or offering a simplified, generalized transport mechanism for applications to utilize. However, this approach also introduces complexities in OS design and could potentially impact performance.

  Ultimately, a world without TCP or UDP would likely see a more fragmented and less efficient internet. The standardized, universally adopted nature of these protocols is a key contributor to the internet's success. Their removal would necessitate significant re-engineering of the entire networking landscape and potentially hinder the seamless communication we currently take for granted. The post leaves open the possibility of novel solutions emerging, but emphasizes the immense challenge of replicating the functionality and widespread adoption of these essential protocols.

  • networking
  • protocols
  • TCP
  • UDP
  • Internet
  • Communication
  • low-level networking
  • Computer Science
  • network protocols
  • data transfer
  • ip
  • network stack
  • osi model
  • alternatives to tcp/udp
  • network fundamentals

  Summary of Comments ( 60 )
  https://news.ycombinator.com/item?id=43169103

  Verbose tl;dr

  Hacker News users discussed alternatives to TCP/UDP and the implications of not using them. Some highlighted the potential of QUIC and HTTP/3 as successors, emphasizing their improved performance and reliability features. Others explored lower-level protocols like SCTP as a possible replacement, noting its multi-streaming capabilities and potential for specific applications. A few commenters pointed out that TCP/UDP abstraction is already somewhat eroded in certain contexts like RDMA, where applications can interact more directly with the network hardware. The practicality of replacing such fundamental protocols was questioned, with some suggesting it would be a massive undertaking with limited benefits for most use cases. The discussion also touched upon the roles of the network layer and the possibility of protocols built directly on IP, acknowledging potential issues with fragmentation and reliability.

  The Hacker News post titled "What would happen if we didn't use TCP or UDP?" sparked a discussion with several interesting comments exploring alternatives and the fundamental roles of TCP and UDP.

  One commenter highlighted the existence of other protocols like QUIC and SCTP, suggesting that the question isn't entirely hypothetical, as the internet is already exploring alternatives. They mentioned that QUIC, in particular, is gaining traction. Another commenter pointed out that HTTP/3 uses QUIC, further emphasizing the shift away from exclusive reliance on TCP and UDP.

  Delving deeper into the theoretical aspects, a user explained that IP itself doesn't mandate TCP or UDP. They described how the IP protocol provides a "best-effort" delivery mechanism, and TCP/UDP build upon it to offer features like reliability (TCP) and connectionlessness (UDP). They further explained that one could theoretically implement other protocols on top of IP.

  Another comment emphasized the importance of some protocol for managing port numbers and multiplexing applications. They argued that even if TCP/UDP weren't used, a similar system would be needed to handle these functionalities. This highlighted the core problem that TCP/UDP solve, which is not inherently tied to their specific implementations.

  One commenter humorously suggested ICMP as an alternative, acknowledging its impracticality but emphasizing the theoretical possibility of building something upon it. This highlighted the point that IP itself is the foundational layer, and other protocols are built on top.

  Expanding on the core functionalities, another comment explained that flow control and congestion control are not inherent to IP and are managed by higher-level protocols. They explained that without mechanisms like those provided by TCP, the network would quickly become congested and unusable.

  Another commenter proposed a thought experiment of removing only UDP, highlighting the reliance of DNS and other services on UDP and the disruptive consequences of such a change. This highlighted the specific niche filled by UDP and its importance to the current internet infrastructure.

  Finally, some comments discussed the historical context of TCP and UDP, mentioning pre-IP protocols like IPX/SPX, and how these offered similar functionalities. This offered a perspective on how the current internet architecture evolved and that the core concepts predate TCP/UDP.

  In summary, the comments on the Hacker News post explored various facets of the question, from existing alternatives and their adoption, to the fundamental roles of TCP/UDP in managing ports, multiplexing applications, and providing crucial functionalities like flow control and congestion control. The discussion also touched upon the theoretical possibility of designing entirely new protocols on top of IP and considered the practical implications of removing either UDP or TCP.

• NAT Is the Enemy of Low Power Devices

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  Posted: 2025-02-10 19:12:36

  Verbose tl;dr

  Network Address Translation (NAT) presents significant challenges for battery-powered IoT devices aiming for low power consumption. Because devices behind NAT can't be directly addressed from the outside, they must maintain persistent outbound connections to receive data, negating the power-saving benefits of sleep modes. Techniques like keep-alive messages or frequent polling to maintain these connections consume significant energy. This post advocates for solutions that bypass NAT, such as IPv6 with its vast address space enabling globally routable unique addresses for each device, or by employing intermediaries like a message broker positioned outside the NAT. These approaches allow devices to initiate communication only when necessary, drastically reducing power consumption and extending battery life.

  The blog post "NAT Is the Enemy of Low Power Devices" on golioth.io elaborates on the significant challenges Network Address Translation (NAT) presents to Internet of Things (IoT) devices, particularly those operating under low-power constraints. The core argument revolves around the inherent incompatibility between NAT's design, which assumes client-initiated connections, and the operational requirements of many battery-powered IoT devices that need to receive inbound data efficiently.

  The author meticulously explains that conventional internet communication relies on devices having globally unique IP addresses. NAT, commonly implemented in home and enterprise networks, allows multiple devices to share a single public IP address, conserving the limited pool of IPv4 addresses. This is achieved by mapping internal private IP addresses to the public IP address and maintaining a translation table to route incoming traffic correctly. However, this mechanism typically requires the internal device to initiate an outbound connection first, establishing a mapping entry in the NAT table, before external services can reach it.

  This poses a serious problem for low-power devices, as maintaining an active connection for inbound data consumes considerable energy. Keeping the radio active and regularly sending "keep-alive" messages to maintain the NAT mapping defeats the purpose of power-saving sleep modes. The article highlights the trade-off between responsiveness and battery life, forcing developers to choose between promptly receiving data and extending battery longevity.

  The blog post further explores the difficulties in implementing workarounds like port forwarding and hole punching. Port forwarding, while a viable solution, requires manual configuration on the router and exposes security vulnerabilities. Hole punching, a technique involving both the device and a server connecting to a third-party rendezvous server to establish a direct connection, is described as complex and unreliable, especially behind symmetric NATs.

  As a potential solution, the article advocates for protocols specifically designed for constrained devices, such as CoAP and MQTT, which operate over UDP and offer features like publish-subscribe messaging, reducing the need for constant connections. These protocols, combined with cloud services designed for IoT, can bypass the limitations of NAT by leveraging always-on cloud servers as intermediaries. The server maintains a persistent connection, acting as a bridge between external services and the low-power device, relaying messages efficiently while allowing the device to remain in a low-power state. In conclusion, the author emphasizes that addressing the NAT problem is crucial for the widespread adoption and efficient operation of low-power IoT devices, urging for greater consideration of NAT's implications in the design and deployment of such devices.

  • NAT
  • Network Address Translation
  • Low Power Devices
  • IoT
  • Internet of Things
  • UDP
  • TCP
  • Firewall
  • networking
  • connectivity
  • Embedded Systems
  • Power Consumption
  • Battery Life
  • CoAP
  • MQTT

  Summary of Comments ( 83 )
  https://news.ycombinator.com/item?id=43003999

  Verbose tl;dr

  Several commenters on Hacker News discussed the challenges of NAT traversal for low-power devices, agreeing with the article's premise. Some suggested solutions like using a TURN server or a lightweight VPN, while others pointed out the benefits of IPv6 in eliminating the need for NAT entirely. One commenter highlighted the trade-offs between power consumption and complexity when implementing these workarounds, and another mentioned the difficulty of managing NAT keepalives with devices that sleep frequently. The issue of scaling these solutions for a large number of devices was also raised. Several users shared personal anecdotes of struggling with similar NAT issues. One commenter proposed a simpler approach involving a central server that all devices could communicate with, bypassing direct peer-to-peer communication and thus avoiding NAT complications altogether.

  The Hacker News post "NAT Is the Enemy of Low Power Devices" generated several comments discussing the challenges of Network Address Translation (NAT) for low-power, battery-operated IoT devices.

  Several commenters agreed with the article's premise. One highlighted the inherent difficulty in establishing inbound connections to devices behind NAT, emphasizing the power consumption overhead associated with maintaining persistent connections or using techniques like keep-alives. They also mentioned the complexities introduced by Carrier-grade NAT (CGNAT), where multiple layers of NAT further complicate inbound connections.

  Another commenter pointed out the security implications of opening ports on a home router for these devices, suggesting that it exposes the entire local network to potential vulnerabilities. They advocated for cloud-based solutions like the one offered by Golioth (the article's author), where devices initiate outbound connections to a central server, eliminating the need for inbound port forwarding.

  The discussion also touched upon alternative approaches to circumvent NAT limitations. One commenter suggested using protocols designed for peer-to-peer communication, like WebRTC, which can establish connections even behind NAT. However, another commenter countered that WebRTC still requires a signaling server and might not be suitable for all low-power applications due to its relatively high overhead.

  Some commenters questioned the framing of NAT as the "enemy." They argued that NAT is a crucial part of the current internet infrastructure and that the real challenge lies in developing efficient protocols and architectures for IoT devices that can work within the constraints of NAT. They proposed solutions like using UDP hole punching or having devices establish outgoing connections to a central server.

  One commenter explored the specific challenges posed by CGNAT, noting the scarcity of IPv4 addresses and the consequent widespread deployment of CGNAT by internet service providers. They mentioned techniques like STUN (Session Traversal Utilities for NAT) and TURN (Traversal Using Relays around NAT) but acknowledged their limitations and complexity, particularly for low-power devices.

  Finally, a few commenters mentioned specific technologies and protocols, like MQTT and CoAP, which are commonly used in IoT and are designed to be efficient in low-power and bandwidth-constrained environments. They discussed how these protocols can be used in conjunction with cloud-based services to overcome the challenges posed by NAT.