## 2 In-Network Computing: What and Why  
INC represents a paradigm shift from the traditional host-centric models of cloud and edge computing to a distributed, network-embedded approach, where computation is integrated directly into the network fabric [19].  
The original INC concept dates back to the '90s, with the theorization of active networks, a technology that allows for the injection of customized programs into network nodes, thus enabling in-network processing and storage services [27]. In active networks, routers can process user data as they flow through them, performing tasks such as caching, compression, and even data fusion or filtering. Traditional (passive) packets are replaced by active capsules, which encapsulate lightweight programs that can be executed at intermediate nodes. These capsules not only allow for dynamic computation but also enable the  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference** & **Year** & **Main Topic** & **Focus** \\ \hline
[10] & 2013 & ICN & Comparison of distinct ICN architectures \\ \hline
[11] & 2016 & ICN & Transport-layer approaches \\ \hline
[12] & 2016 & ICN & NDN routing, caching, forwarding and mobility \\ \hline
[13] & 2017 & ICN & In-network security and privacy \\ \hline
[14] & 2019 & ICN & Forwarding strategies in wireless networks \\ \hline
[15] & 2019 & ICN & NDN in vehicular networks \\ \hline
[16] & 2020 & ICN & Naming and caching in 5G and beyond networks \\ \hline
[17] & 2020 & ICN & Caching in vehicular NDN \\ \hline
[18] & 2021 & ICN & Access control mechanisms in NDN \\ \hline
[19] & 2022 & INC & Programmable data planes and applications \\ \hline
[20] & 2022 & ICN & NDN routing \\ \hline
[21] & 2023 & INC & In-network ML \\ \hline
[22] & 2023 & ICN & In-network caching strategies \\ \hline
[23] & 2024 & INC & Smart NICs \\ \hline
[24] & 2024 & ICN & Software-defined NDN \\ \hline
[25] & 2024 & INC & Enabling technologies and architectures \\ \hline
[26] & 2024 & INC & In-network ML \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of related surveys and their focus.  
propagation of code to nodes along a network path [28]. By doing so, the network itself becomes an extension of user applications, enabling faster protocol innovation. For example, active nodes can execute customized protocols to reduce retransmission latency or cache dynamic content closer to the client.  
Due to the technological limitations of the 1990s, including restricted computational capacity and network resources, the active network paradigm was not adopted in practical deployments and eventually faded from focus. Today, with the advent of powerful computational capabilities and advanced networking infrastructures, the core principles of active networks have been revamped, promoting the realization of the INC paradigm.  
In future 6G networks, INC can allow complex tasks to be executed on data as it traverses the network, bringing significant advantages, like reduced computing latency, lower data traffic, alleviation of network congestion, and reduced load on centralized servers. Computations can be dynamically performed closer to clients or data sources, bypassing the need to transmit data to distant cloud servers for processing. This reduction in round-trip latency is particularly critical for applications requiring real-time responses, such as autonomous vehicles, industrial automation and XR. Unlike edge computing, which relies on purpose-built servers at the network's edge, INC leverages programmable network elements such as switches and routers, thus eliminating the dependency on dedicated computing infrastructure and enabling real-time task distribution across the network, providing enhanced flexibility and scalability.