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Link failures are commonly observed in computer networks, including the newly emerging Software Defined Network (SDN). Considering that failure recovery methods used in traditional networks cannot be applied to SDN networks directly, we propose a method named pro-VLAN in this paper, which calculates a backup path and assigns a unique VLAN id for each link of the network based on the protection mechanism. It makes the most of SDN’s features and can recover a single link failure in SDN with the advantages of high efficiency, strong scalability and wide applicability. More specifically, high efficiency (i.e., a fast failure recovery with a low memory consumption) is achieved by calculating backup paths for each link instead of each flow and using group tables to switch backup paths automatically and locally when failures occur. Strong scalability (i.e., the amount of backup flow entries per switch is stable) is achieved by keeping the amount of links per switch no matter how the network scale extends or how the amount of flows increases. Wide applicability is achieved by always finding a path available without modifying any hardware or protocol as long as the network is still reachable after a link failure. Simulation results and mathematical analysis demonstrate that both pro-VLAN and a flow-based protection method achieve a fast failure recovery, while pro-VLAN consumes less than 1% of the forwarding entries to store backup paths as compared to the flow-based method. Moreover, when the network scale increases from 10 to 60 switches by 500%, the increase of the number of backup flow entries per switch built by pro-VLAN is only less than 50%.

Software-Defined Networking (SDN) is an emerging architecture of computer networking. OpenFlow is considered as the first and currently most popular standard southbound interface of SDN. It is a communication protocol which enables the SDN controller to directly interact with the forwarding plane, which makes the network more flexible and programmable. The promising and widespread use makes the reliability of OpenFlow important. The OpenFlow bundle mechanism is a new mechanism proposed by OpenFlow protocol to guarantee the completeness and consistency of the messages transmitted between SDN devices like switches and controllers. In this paper, we use Communication Sequential Processes (CSP) to formally model the OpenFlow bundle mechanism. By adopting the models into the model checker Process Analysis Toolkit (PAT), we verify the relevant properties of the mechanism, including deadlock freeness, parallelism, atomicity, order property and schedulability. Our formalization and verification show that the mechanism can satisfy these properties, from which we can conclude that the mechanism offers a better way to guarantee the completeness and consistency.

SDN is approaching its own structure of acceptance. Therefore, the increasing deployment of SDNs is being discussed as a possible approach, appearing in the development of the hybrid SDN networks. An foremost work in the hybrid SDN networks is bandwidth allocation, taking into account the integration of both SDN-enabled and conventional switches. The network loop in layer 2 switches is skipped in Spanning Tree Protocol (STP) by ceaselessly watching the network to trace all links and block the unwanted ones. Bridge loops will occur anytime there’s a redundant Layer2 way between ends. By default, switches forward broadcast/multicast out all ports, other than the port from that the broadcast/multicast was delivered. Once a switch loop is brought in the network, broadcast messages are going to be broadcasted more often leading to broadcast storms. The Spanning-tree algorithm enforces a distributed divergent of the Bellman-Ford iterative algorithm that always looks for the optimal solution and selects an optimal influential switch anytime. In this paper we use controller’s global network view for resolving loop problem in layer 2 network. SDN controller acts on broadcast packets received from switch-ports and host-ports differently that is if the broadcast packets received from host ports, the SDN controller broadcasts these packets to all ports and if broadcast packets is received from switch ports, only some switches broadcasts these packets on all ports instead of all switches.

Software defined networking (SDN) is a promising technology that is expected to dominate the networking market, especially wired networking. This network architecture overcomes many of the shortcomings in traditional transmission control protocol (TCP) networking by decoupling data and control planes and centralising the logic/control in the network. A successful and popular implementation of SDN is the OpenFlow protocol, which has lately been implemented by the largest Internet and networking corporations. To date, however, there is little research related to wireless networks and the integration of the OpenFlow protocol. This paper presents the results of a comprehensive survey of trials to integrate SDN technology with wireless networks. The applications of such integration are highlighted, such as performance, load balancing, and networks in rural areas.

Forwarding lookup in the open flow switch can be done for each arriving packet by every switch in path. In view of the possible resource shortage in the existing SDN technology; this paper describes a fine-grained OpenFlow multiple-table pipeline architecture that efficiently stores the flow table in the TCAM memories. Simulations show that the strategy reduces the TCAM usage for the multipletable mapping scheme [1] by 14.3%, which is important for scalable designs of OpenFlow data planes.