[Paper Review] An SDN-IoT-based Framework for Future Smart Cities: Addressing Perspective

Uttam Ghosh, Pushpita Chatterjee+2 more|arXiv (Cornell University)|Jul 22, 2020

IoT and Edge/Fog Computing22 references4 citations

TL;DR

This paper proposes a distributed, SDN-IoT-based IPv6 addressing scheme for future smart cities, where new devices dynamically obtain unique IP addresses from neighboring devices, eliminating broadcast flooding and reducing addressing overhead and latency. The scheme achieves high scalability, low complexity, and energy efficiency by leveraging existing devices as address proxies, outperforming DHCP and DAD in performance metrics.

ABSTRACT

In this Chapter, a software-defined network (SDN)-based framework for future smart cities has been proposed and discussed. It also comprises a distributed addressing scheme to facilitate the allocation of addresses to devices in the smart city dynamically. The framework is dynamic and modules can be added and omitted by a centralized controlling unit without disturbing the other components of the framework and other modules may be updated accordingly. In the proposed addressing scheme, a new Internet of Things (IoT) device will receive an IP address from one of their existing neighboring peer devices. This allows devices in the city to act as a proxy and generate a set of unique IP addresses from their own IP addresses, which can then be assigned to new (joining) devices; hence, reducing addressing overhead and latency, as well as avoiding the need to send broadcast messages during the address allocation process. Thus, it achieves considerable bandwidth and energy savings for the IoT devices.

Motivation & Objective

• To address the scalability and efficiency challenges of IP address allocation in large-scale SDN-IoT-based smart city networks.
• To reduce addressing overhead and latency caused by traditional protocols like DHCP and DAD, which rely on network-wide broadcasts.
• To design a distributed, dynamic addressing mechanism that ensures unique IPv6 addresses without centralized control or complex conflict detection.
• To minimize energy and bandwidth consumption in IoT devices by avoiding broadcast storms and reducing message exchanges.
• To enhance network scalability and reliability in smart city environments with high device density and dynamic device onboarding.

Proposed method

• Devices in the network act as proxies, dynamically generating unique IPv6 addresses from their own assigned addresses to allocate to new joining devices.
• New devices request an IP address from one of their directly connected neighboring devices, reducing the need for network-wide discovery or broadcast messages.
• The scheme uses a hierarchical addressing approach where each device maintains a local address pool derived from its own IPv6 address, ensuring uniqueness through controlled allocation.
• The addressing mechanism avoids Duplicate Address Detection (DAD) by pre-assigning non-conflicting addresses, eliminating the need for probe flooding and timer-based conflict resolution.
• The SDN controller manages network-wide policy and coordination, while the data plane handles local address assignment, enabling centralized control with distributed execution.
• Performance is evaluated using metrics including addressing latency, overhead (message count), uniqueness, scalability, and complexity, with theoretical analysis based on network diameter (d), average hop latency (t), and number of links (l).

Experimental results

Research questions

• RQ1 How can IP address allocation in large-scale SDN-IoT smart city networks be made scalable and efficient with minimal network overhead?
• RQ2 What is the impact of eliminating broadcast-based discovery (e.g., DHCP, DAD) on addressing latency and energy consumption in IoT devices?
• RQ3 Can a distributed, neighbor-based addressing scheme ensure unique IPv6 addresses without relying on centralized servers or complex conflict detection mechanisms?
• RQ4 How does the proposed scheme compare to DHCP and DAD in terms of addressing latency, message overhead, and scalability as network size increases?
• RQ5 What is the computational and memory complexity of the proposed scheme compared to existing approaches in resource-constrained IoT environments?

Key findings

• The proposed addressing scheme achieves O(2*t) addressing latency, significantly lower than DHCP and DAD, which both have O(2*t*d) latency due to network-wide probing.
• Addressing overhead is reduced to O(2*l/n), compared to O(n²) for DHCP and DAD, making the scheme highly scalable in large networks.
• The scheme ensures address uniqueness without requiring Duplicate Address Detection (DAD), eliminating the risk of broadcast storms and reducing message volume.
• The complexity of the scheme is low, as it does not require maintaining address blocks or complex address generation functions; instead, existing devices act as proxies with minimal state.
• The scheme enables substantial bandwidth and energy savings for IoT devices by avoiding repeated broadcast messages during address allocation.
• Theoretical analysis confirms that the scheme maintains high performance even as network size increases, demonstrating strong scalability compared to centralized or broadcast-based alternatives.