NFV環(huán)境下級聯(lián)故障分析及解決方案研究
發(fā)布時間：2019-04-15 18:41
【摘要】：隨著互聯(lián)網(wǎng)的發(fā)展,上層服務需求越來越多樣化,傳統(tǒng)的底層網(wǎng)絡功能迫于專屬硬件的限制,無法快速更新適應。網(wǎng)絡功能虛擬化(Network Function Virtualization,NFV)將IT虛擬化技術引入傳統(tǒng)電信網(wǎng)絡,實現(xiàn)了傳統(tǒng)網(wǎng)絡功能的軟硬件分離,使得網(wǎng)絡功能可編程動態(tài)伸縮,大大增強了網(wǎng)絡的更新迭代速度。然而,傳統(tǒng)電信網(wǎng)絡和IT網(wǎng)絡在可靠性的要求上存在較大差異,級聯(lián)故障問題頻繁發(fā)生在IT網(wǎng)絡系統(tǒng)中,針對電信網(wǎng)絡的高可靠性要求,NFV環(huán)境下的網(wǎng)絡的級聯(lián)故障問題應當引起重視。本文首先從服務功能鏈(Service Function Chain,SFC)的角度分析了NFV環(huán)境下故障擴散的模式,通過實驗總結出兩種不同的故障擴散模式:(1)當不同服務功能鏈共享的資源故障時,故障將在大量不同服務鏈間擴散。(2)當服務功能鏈上不同功能模塊間性能不匹配時,故障會沿著服務功能鏈的性能瓶頸模塊向上游模塊擴散。為了防止共享資源故障引起的大面積故障擴散,本文采用對關鍵資源如共享資源加強保護的辦法提高系統(tǒng)的可靠性,阻斷故障的擴散。首先針對NFV多層虛擬化特點,對其不同層次中各模塊之間的存在的多種關系(依賴、備份、負載均衡)進行抽象,建立了一個三值狀態(tài)多層依賴模型。然后提出一個優(yōu)化系統(tǒng)可靠性的備份資源分配算法,仿真結果表明,算法能得到最優(yōu)解或近似最優(yōu)解。從而從備份資源分配角度為實現(xiàn)故障隔離提供思路。為了解決服務鏈上不同服務功能模塊服務能力不匹配帶來的擴容風暴問題,本文提出了聯(lián)動擴容算法。該算法主要思想在于預測出瓶頸模塊擴容后對下游模塊的影響,將受影響的模塊與瓶頸模塊聯(lián)動擴容,從而避免多次擴容。具體方法是利用神經(jīng)網(wǎng)絡,建立了擴容量和數(shù)據(jù)流的輸入輸出速率之間的關系模型,使得上游節(jié)點的擴容對下游節(jié)點的影響可以量化,提前對下游受波及的節(jié)點進行擴容,防止了故障的擴散。仿真結果表明,聯(lián)動擴容算法避免了單點獨立擴容可能導致的二次服務功能不匹配問題,節(jié)約了系統(tǒng)擴容的總時間,降低了平均服務響應延遲。最后,為更好地應用上述算法,在目前業(yè)界的NFV架構基礎上,實現(xiàn)了NFV環(huán)境下故障隔離架構,該架構根據(jù)上述算法的輸入輸出需求,增加了監(jiān)視器模塊和算法部署模塊,并給出了運行實例,為增強算法的實用價值提供參考。
[Abstract]:With the development of Internet, the demand of upper layer service is becoming more and more diversified. The traditional bottom network function is forced by the limitation of exclusive hardware, and can not be updated and adapted quickly. Network function Virtualization (Network Function Virtualization,NFV (Network function Virtualization) introduces IT virtualization technology into traditional telecommunication network, realizes the separation of hardware and software of traditional network function, makes the network function dynamically and programmatically scalable, and greatly enhances the iterative speed of network update. However, there is a great difference between the traditional telecommunication network and the IT network in the reliability requirements. Cascading failures occur frequently in the IT network system, aiming at the high reliability requirements of the telecommunication network. The cascading fault of network in NFV environment should be paid more attention. In this paper, the mode of fault diffusion in NFV environment is analyzed from the point of view of service function chain (Service Function Chain,SFC), and two different modes of fault diffusion are summarized by experiment: (1) when the resource shared by different service function chain fails, The fault will spread among a large number of different service chains. (2) when the performance of different functional modules on the service function chain does not match, the fault will spread along the performance bottleneck module of the service function chain to the upstream module. In order to prevent the large-scale fault diffusion caused by shared resource fault, this paper adopts the method of strengthening the protection of key resources such as shared resource to improve the reliability of the system, and to block the spread of fault. According to the characteristics of NFV multi-layer virtualization, this paper abstracts the multi-layer relationships (dependency, backup, load balancing) between the modules in different levels, and establishes a three-valued state multi-layer dependency model. Then a backup resource allocation algorithm is proposed to optimize the reliability of the system. The simulation results show that the algorithm can obtain the optimal solution or approximate optimal solution. From the point of view of backup resource allocation, this paper provides a train of thought for the realization of fault isolation. In order to solve the problem of capacity expansion caused by the mismatch of service capability of different service function modules in service chain, this paper proposes a linkage capacity expansion algorithm. The main idea of this algorithm is to predict the impact of bottleneck module expansion on downstream modules, and to link the affected modules with bottleneck modules so as to avoid multiple capacity expansion. The specific method is to use the neural network to establish the relationship model between the expansion capacity and the input / output rate of the data stream, so that the influence of the upstream node expansion on the downstream nodes can be quantified, and the affected nodes in the downstream nodes can be expanded in advance. The failure was prevented from spreading. The simulation results show that the linkage expansion algorithm avoids the mismatch problem of secondary service function which may be caused by single point independent capacity expansion, saves the total time of system expansion, and reduces the average service response delay. Finally, in order to better apply the above algorithms, based on the current industry NFV architecture, the fault isolation architecture under the NFV environment is implemented. According to the input and output requirements of the above algorithms, the monitor module and the algorithm deployment module are added. A running example is given to provide a reference for the practical value of the enhancement algorithm.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN915.0
本文編號：2458386
[Abstract]:With the development of Internet, the demand of upper layer service is becoming more and more diversified. The traditional bottom network function is forced by the limitation of exclusive hardware, and can not be updated and adapted quickly. Network function Virtualization (Network Function Virtualization,NFV (Network function Virtualization) introduces IT virtualization technology into traditional telecommunication network, realizes the separation of hardware and software of traditional network function, makes the network function dynamically and programmatically scalable, and greatly enhances the iterative speed of network update. However, there is a great difference between the traditional telecommunication network and the IT network in the reliability requirements. Cascading failures occur frequently in the IT network system, aiming at the high reliability requirements of the telecommunication network. The cascading fault of network in NFV environment should be paid more attention. In this paper, the mode of fault diffusion in NFV environment is analyzed from the point of view of service function chain (Service Function Chain,SFC), and two different modes of fault diffusion are summarized by experiment: (1) when the resource shared by different service function chain fails, The fault will spread among a large number of different service chains. (2) when the performance of different functional modules on the service function chain does not match, the fault will spread along the performance bottleneck module of the service function chain to the upstream module. In order to prevent the large-scale fault diffusion caused by shared resource fault, this paper adopts the method of strengthening the protection of key resources such as shared resource to improve the reliability of the system, and to block the spread of fault. According to the characteristics of NFV multi-layer virtualization, this paper abstracts the multi-layer relationships (dependency, backup, load balancing) between the modules in different levels, and establishes a three-valued state multi-layer dependency model. Then a backup resource allocation algorithm is proposed to optimize the reliability of the system. The simulation results show that the algorithm can obtain the optimal solution or approximate optimal solution. From the point of view of backup resource allocation, this paper provides a train of thought for the realization of fault isolation. In order to solve the problem of capacity expansion caused by the mismatch of service capability of different service function modules in service chain, this paper proposes a linkage capacity expansion algorithm. The main idea of this algorithm is to predict the impact of bottleneck module expansion on downstream modules, and to link the affected modules with bottleneck modules so as to avoid multiple capacity expansion. The specific method is to use the neural network to establish the relationship model between the expansion capacity and the input / output rate of the data stream, so that the influence of the upstream node expansion on the downstream nodes can be quantified, and the affected nodes in the downstream nodes can be expanded in advance. The failure was prevented from spreading. The simulation results show that the linkage expansion algorithm avoids the mismatch problem of secondary service function which may be caused by single point independent capacity expansion, saves the total time of system expansion, and reduces the average service response delay. Finally, in order to better apply the above algorithms, based on the current industry NFV architecture, the fault isolation architecture under the NFV environment is implemented. According to the input and output requirements of the above algorithms, the monitor module and the algorithm deployment module are added. A running example is given to provide a reference for the practical value of the enhancement algorithm.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN915.0
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