Software-defined Networking Flow Research Articles

CountMax: A Lightweight and Cooperative Sketch Measurement for Software-Defined Networks

In a software-defined network (SDN), statistics information is of vital importance for different applications, such as traffic engineering, flow rerouting, and attack detection. Since some resources, e.g., ternary content addressable memory, SRAM, and computing capacity, are often limited on SDN switches, traffic measurements based on flow tables or sampling become infeasible. In fact, sketches provide a promising building block for filling this void by monitoring every packet with fixed-size memory. Although many efficient sketches have been designed, our analysis shows that existing sketch-based measurement solutions may suffer from severe computing overhead on switches especially under high traffic load that significantly interferes with switch’s basic functions, such as flow rule setup and modification. In this paper, we present CountMax, a lightweight and cooperative sketch for traffic measurement, which can achieve low-amortized processing overhead and tight estimation bounds, to track large flows in SDNs. We also discuss how to apply CountMax to support a variety of applications. We have implemented the proposed algorithm on our open switches. Testbed experiments and extensive simulation results show that CountMax consumes only 1/3–1/2 computing overhead and reduces the average estimation error by 20%–30%, compared with the existing solutions under the same memory size.

Fastlane-ing more flows with less bandwidth for software-Defined networking

Software-Defined Networking (SDN) has greatly boosted the productivity of data center networking and cloud computing. It introduces a central controller to take over most functions that otherwise reside in distributed forwarding devices. Such a centralized design, however, tends to make the control channel a bottleneck due to bandwidth fatigue. Only when this bottleneck is addressed can SDN greater benefit networking and computing infrastructures. Existing work saves control channel bandwidth at the expense of losing flow visibility. This paper designs and implements FastLane, a framework for bandwidth-efficient yet throughput-boosting SDN flow setup without sacrificing global flow visibility. FastLane informs only one on-path switch of a flow’s forwarding path while switches themselves cooperate to complete flow setup. FastLane thus keeps minimum traffic for flow setup in the control channel and leaves the rest to the data plane. We optimize the switch selection toward minimizing flow setup latency. To leverage the saved bandwidth for setting up more flows and therefore achieving higher throughput, we propose delegating certain flow setups from ingress to en-route switches. We prototype FastLane by modifying FloodLight controller and Open vSwitch. The results demonstrate FastLane’s benefits to higher SDN throughput with limited switching fabric overhead.

Analytical Model for SDN Signaling Traffic and Flow Table Occupancy and Its Application for Various Types of Traffic

Software defined networking (SDN) has emerged as a promising networking paradigm overcoming various drawbacks of current communication networks.The control and data plane of switching devices is decoupled and control functions are centralized at the network controller. In SDN, each new flow introduces additional signaling traffic between the switch and the controller. Based on this traffic, rules are created in the flow table of the switch, which specify the forwarding behavior. To avoid table overflows, unused entries are removed after a predefined time-out period. Given a specific traffic mix, the choice of this time-out period affects the tradeoff between signaling rate and table occupancy . As a result, network operators have to adjust this parameter to enable a smooth and efficient network operation. Due to the complexity of this problem caused by the various traffic flows in a network, a suitable abstraction is necessary in order to derive valid parameter values in time. The contribution of this paper is threefold. First, we formulate a simple analytical model that allows optimizing the network performance with respect to the table occupancy and the signaling rate. Second, we validate the model by means of simulation. Third, we illustrate the impact of the time-out period on the signaling traffic and the flow table occupancy for different data-plane traffic mixes and characteristics. This includes scenarios with single application instances, as well as multiple application instances of different application types in an SDN-enabled network.

Novel elastic protection against DDF failures in an enhanced software-defined SIEPON

Abstract Ever-increasing bandwidth demands on passive optical networks (PONs) are pushing the utilization of every fiber strand to its limit. This is mandating comprehensive protection until the end of the distribution drop fiber (DDF). Hence, it is important to provide refined protection with an advanced fault-protection architecture and recovery mechanism that is able to cope with various DDF failures. We propose a novel elastic protection against DDF failures that incorporates a software-defined networking (SDN) capability and a bus protection line to enhance the resiliency of the existing Service Interoperability in Ethernet Passive Optical Networks (SIEPON) system. We propose the addition of an integrated SDN controller and flow tables to the optical line terminal and optical network units (ONUs) in order to deliver various DDF protection scenarios. The proposed architecture enables flexible assignment of backup ONU(s) in pre/post-fault conditions depending on the PON traffic load. A transient backup ONU and multiple backup ONUs can be deployed in the pre-fault and post-fault scenarios, respectively. Our extensively discussed simulation results show that our proposed architecture provides better overall throughput and drop probability compared to the architecture with a fixed DDF protection mechanism. It does so while still maintaining overall QoS performance in terms of packet delay, mean jitter, packet loss, and throughput under various fault conditions.

Software-defined network flow table overflow attacks and countermeasures

Software-defined network (SDN) is proposed as a new concept in computer networks, which separates the control plane from the data plane. And it provides a programmable network architecture that could facilitate rapid network innovation. OpenFlow is a network protocol that standardises the communications between OpenFlow controllers and OpenFlow switches. It is considered as an enabler of SDN. The flow table in OpenFlow switches plays a critical role in OpenFlow-based SDN, which stores the rules populated by the controllers for controlling and directing the packet flows in SDN. Nevertheless, they also become a new target of malicious attacks. This paper analyses the flow table overflow attack, a type of denial of service attacks, and proposes a novel eviction algorithm, dynamic in/out balancing with least frequently used eviction (DIOB/LFU), at service level to defend against the flow table overflow attacks.

Small-Packet Flows in Software Defined Networks: Traffic Profile Optimization

This paper proposes a method for optimizing bandwidth usage in Software Defined Networks (SDNs) based on OpenFlow. Flows of small packets presenting a high overhead, as the ones generated by emerging services, can be identified by the SDN controller, in order to remove header fields that are common to any packet in the flow, only during their way through the SDN. At the same time, several packets can be multiplexed together in the same frame, thus reducing the overall number of frames. The method can be useful for providing QoS while the packets are traversing the SDN. Four kinds of small-packet traffic flows are considered (VoIP, UDP and TCP-based online games, and ACKs from TCP flows). Both IPv4 and IPv6 are studied, and significant bandwidth savings (up to 68 % for IPv4 and 78 % for IPv6) can be obtained for the considered kinds of traffic. The optimization method is also applied to different public Internet traffic traces, and significant reductions in terms of packets per second are achieved. Results show that bandwidth consumption is also reduced, especially in those traces where the percentage of small packets is high. Regarding the effect on QoS, the additional delay can be kept very low (below 1 millisecond) when the throughput is high, but it may become significant for low- throughput scenarios. Thus, a trade-off between bandwidth saving and additional delay appears in those cases.

Source-Timed SDN Video Switching of Packetized Video

The broadcast industry is considering a move from serial digital interface (SDI) infrastructure to a computer-networked infrastructure. Professional media networking will enhance flexibility and agility of the broadcast plant, reduce and simplify cabling, provide for format-agnostic transport, and allow media organizations to benefit from the economies of scale of commercial off-the-shelf (COTS) networking hardware. One key element of video processing is synchronous (“clean”) switching between video sources. The accuracy of the switch point recommended by SMPTE Recommended Practice (RP) 168 is on the order of 10 μs. Unfortunately, the current speed of networking switch flow rule changes using software-defined networking (SDN) is on the order of 1 to 10 ms, and the speed of rule changes is not highly deterministic. To solve this problem, source-timed video switching separates the actions of updating SDN flow rules from the timing of the actual video switch. This technique first adds new SDN flow rules to the networking switch that match a packet header value that is not currently being transmitted. Then, the video source changes its output's packet header value to the new value in the flow rule at the precise RP 168 video switch point. The new packet header value matches the new flow rules; thus, the effect of these two steps achieves precisely timed synchronous video switching (which can be compared with the actions of “preview” and “take” on a video switcher). Fox has developed a proof-of-concept of source-timed video switching using live high-definition SDI sources packetized using SMPTE 2022-6 and synchronously switched on a COTS 10 Gbit/sec Ethernet switch.