# Software Defined Wireless Mesh Network Flat Distribution Control Plane
## 1 Introduction
Keeping an overall view of a large network surely generates a huge amount of information about the physical plane state. Furthermore, the massive volume of a control flow would produce a heavy load to the SDN controller which could degrade the controller performance [17]. As a consequence, network scalability problems are arising. The current SDN topology discovery scheme, which is designed for wired networks, does not suffice for wireless networks requirements. Also, it does not collect any quality of service (QoS) properties of underlying network elements. This paper addresses distributed multiple-domain SDWMN, as presented in Figure 1, which can be deployed for various applications of WMN. Generally, they are decomposed into geographical or administrative interconnected domains, each domain can consist of mesh routers that are equipped with various wireless interface standard technologies, generally any IEEE802.11 standard with at least two frequency bands (one for the control plane and other for the data plane). The Ad-hoc On-Demand Distance Vector Routing (AODV) is used as a QoS routing protocol and delay is used as the main metric, but this work focuses on finding an appropriate architecture that allows using a state-of-art topology discovery and QoS monitoring using Link Layer Discovery Protocol(LLDP) to offer topological and QoS information for any QoS routing protocol that can reside as application on the application plane of the SDN controller in WMN. Surely this is the heterogeneity and distributed nature that WMN calls for to be more robust to failure and adaptable to user requirements. The state-of-the-art distributed solutions of SDWN are not sufficient for WMN scalability, as it needs a fine-grain control plane that depends on an efficient communication system for inter-controller exchange. We propose FD-SDWMN architecture, a Flat Distributed SDWMN. It distributes the control plane among flat distributed SDN controllers; we show how the control plane initializes dynamically to solve the SDN bootstrap problem. After that, the architecture starts providing the main functionalities such as network traffic engineering and disruption and attack survival. Contrary to currently distributed SDN architectures, WMN based on FD-SDWMN is resilient enough to discriminate links with the best characteristics (bandwidth, latency, packet loss, etc.) for data forwarding. FD-SDWMN is implemented on top of POX [18] OpenFlow controller, and Advanced Message Queuing Protocol AMQP [19]. For FD-SDWMN architecture performance evaluation, we present its functionalities on a Mininet-wifi [20] emulator for SDWN according to a control plane consistency test and two application cases: the topology discovery mechanism for multi-hop networks (the state-of-the-art topology discovery cannot be applied to a multi-hop network such as WMN) and QoS monitoring. The rest of the paper is organized as follows: Section 2 describes the FD-SDWMN architecture, it presents the modules and agents that compose the controller. Section 3 presents the proposed architecture implementation. A detail description of the topology discovery and QoS monitoring is presented in Sections 4-6. In Section 7 this work evaluates the experimental results. Section 8 concludes the paper and presents our future work.