Dynamic routing network algorithm of low voltage

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Dynamic topology:As the channel of communicationchanges, some of the neighbors who were reachable on theprevious channel might not be reachable on the currentchannel and vice versa. As a result the topology of the network changes with the change in frequency of operation resulting in route failures and packet loss.Heterogeneity:Different channels may support differenttransmission ranges, data rates and delay characteristics.Spectrum-Handoff delay:For each transition from onechannel to another channel due to the PU’s activity, thereis a delay involved in the transition called Spectrum- Handoff delay.All these factors decrease the predictability of the cause oftransit-delay and subsequent packet loss on the network. Thetime latency during channel hand-off in cognitive networksmight cause the TCP round trip timer to time out. TCP willwrongly recognize the delays and losses due to the abovefactors as network congestion and immediately take steps toreduce the congestion window size knowing not the cause ofpacket delay. This reduces the efficiency of the protocol insuch environments.动态技术：随着信道通信的变化，一些邻进信道的用户在原信道没有发生变化而在新信道发生变化，或者相反。

网络异常检测与攻击隔离技术(看2.3)

关于论文使用授权的说明学位论文作者完全了解北京邮电大学有关保留和使用学位论文的规定，即：研究生在校攻读学位期间论文工作的知识产权单位属北京邮电大学。学校有权保留并向国家有关部门或机构送交论文的复印件和磁盘，允许学位论文被查阅和借阅；学校可以公布学位论文的全部或部分内容，可以允许采用影印、缩印或其它复制手段保存、汇编学位论文。（保密的学位论文在解密后遵守此规定）
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主动队列管理下大时滞网络路径拥塞控制算法

文章编号：1006 - 9348 (2021)03 - 0268 - 04主动队列管理下大时滞网络路径拥塞控制算法刘国芳，张炜(四川大学锦江学院，四川眉山620860)摘要:与传统的无线网络相比，大时滞网络对路径拥塞环境下的无线通道交换具有较高的要求。

为此提出主动队列管理下大时滞网络路径拥塞控制算法。

首先利用主动队列管理算法对相邻路由节点网络路径的拥塞情况展开预测，进而分析网络路由节点的队列状态;然后以优化后续节点队列、传输距离以及传输方向为目的，从路径概率选择、分组丢弃函数、WSN蚁群路由选取三个角度优化网络路径，从而实现路径拥塞控制。

实验结果表明，上述算法能够有效缩短网络的传输时滞，且能耗和丢包率较低，具有较高的应用价值。

关键词：主动队列管理;无线通道;交换网络;路由；拥塞控制中图分类号:TP399 文献标识码：BPath Congestion Control Algorithm for Large TimeDelay Networks under Active Queue Management 第38卷第3期__________________________计算机仿真____________________________2021年3月LIU Guo -fan g,Z H A N G W ei(Jinjiang College,Sichuan University,Meishan Sichuan620860，China)ABSTRACT：In the large time - delay network,there is a high demand for wireless channel switching in path congestion environment.In this regard,this paper puts forward a path congestion control algorithm with active queue management for large delay networks.Firstly,based on the active queue management algorithm,the congestion of the network path of the adjacent routing nodes was predicted,and the queue status of the network routing nodes was analyzed.Secondly,the optimization of subsequent node queue,transmission distance and transmission direction were taken as indicators to optimize the network path from path probability selection,packet drop function and WSN ant colony routing selection.Eventually,path congestion control was completed.The simulation results show that the algorithm has short transmission delay,low energy consumption and packet loss rate,and high practicability.KEYW ORDS：Active queue management；Wireless channel；Switching network；Routing；Congestion controli引言无线通道交换网络是设定在监测区域中的一些小型路由节点，通过无线通信的方式衍生出的具有多跳性、自组织性的网络系统[|]。

correlated equilibrium

Distributed Energy-Efﬁcient Cooperative Routing in Wireless Networks Ahmed S.Ibrahim,Zhu Han†,and K.J.Ray LiuDepartment of Electrical and Computer Engineering,University of Maryland,College Park,MD20742,USA †Department of Electrical and Computer Engineering,Boise State University,Boise,ID83725,USAAbstract—Recently,cooperative routing in wireless networks has gained much interest due to its ability to exploit the broadcast nature of the wireless medium in designing power-efﬁcient routing algorithms.Most of the existing cooperation-based routing algorithms are implemented byﬁnding a shortest-path routeﬁrst.As such,these routing algorithms do not fully exploit the merits of cooperative communications at the physical layer.In this paper,we propose a cooperation-based routing algorithm,namely,Minimum Power Cooperative Routing (MPCR)algorithm,which makes full use of the cooperative communications while constructing the minimum-power route. The MPCR algorithm constructs the minimum-power route as a cascade of the minimum-power single-relay building blocks from the source to the destination.Hence,any distributed shortest-path algorithm can be utilized toﬁnd the optimal route with polynomial complexity,while guaranteeing certain throughput. We show that the MPCR algorithm can achieve power saving of57.36%compared to the conventional shortest-path routing algorithms.Furthermore,the MPCR algorithm can achieve power saving of37.64%compared to the existing cooperative routing algorithms,in which the selected routes are constructed based on the noncooperative routes.I.I NTRODUCTIONIn wireless networks such as ad hoc networks,nodes spend most of their power in communication,either sending their own data or relaying other nodes’data[1].Therefore,de-signing power-efﬁcient routing algorithms is one of the major concerns in wireless networks.Furthermore,the communi-cation power can be reduced by jointly considering other layers’protocols,which make use of the broadcast nature of the wireless medium.Moreover,these algorithms should be implemented in a distributed way.Therefore,the main goal of this paper is to design a distributed minimum-power routing algorithm for wireless networks,which exploits the broadcast nature of the wireless medium.Recently,cooperative communication for wireless networks has gained much interest due to its ability to mitigate fading through achieving spatial diversity,while resolving the difﬁ-culties of installing multiple antennas on small communication terminals.In cooperative communications,relays are assigned to help a sender in forwarding its information to its receiver. Thus,the receiver gets several replicas of the same informa-tion via independent channels.Various cooperative diversity protocols were proposed and analyzed in[2]-[10].The classical relay channel model based on additive white Gaussian noise(AWGN)channels was presented in[2].In[3], Laneman et al.described various techniques of cooperative communication,such as decode-and-forward,amplify-and-forward,selection relaying,and incremental relaying.In[4],a distributed space-time coded(STC)cooperative scheme was proposed by Laneman et al.In[5]and[6],Sendonaris et al.introduced user cooperation diversity.A two-user CDMA cooperative system,where both users are active and use orthogonal codes,was implemented in this two-part series. In[7],[8],relay-selection schemes for single-and multi-node decode-and-forward cooperative systems were proposed.In [9],the authors have provided SER performance analysis for the decode-and-forward multi-node scheme.Finally,a distrib-uted relay-assignment algorithm for wireless communications has been proposed in[10].The merits of the cooperative communications in the phys-ical layer have been explored.However,the impact of the co-operative communications on the design of the higher layers is not well-understood yet.Routing algorithms,which are based on the cooperative communications and known as cooperative routing[11],is an interesting research area and can lead to signiﬁcant power savings.The cooperative routing proposed in [11]makes use of two facts:the Wireless Broadcast Advantage (WBA)in the broadcast mode and the Wireless Cooperative Advantage(WCA)in the cooperative mode.In the broadcast mode each node sends its data to more than one node,while in the cooperative mode many nodes send the same data to the same destination.The cooperative routing problem has been recently consid-ered in the literature[11]-[15].In[11],the optimum route is found through a dynamic programming algorithm.In[12], the minimum-power route is chosen while guaranteeingﬁxed transmission rate.In[13],Li et al.proposed the Cooperative Shortest Path(CSP)algorithm,which chooses the next node in the route that minimizes the power transmitted by the last L nodes added to the route.Sikora et al.presented in[14] an information-theoretic viewpoint of the cooperative routing in linear wireless network for both the power-limited and bandwidth-limited regimes.In addition,the authors in[14] analyzed the transmitted power,required to achieve a desired end-to-end rate.In[15],the authors proposed three cooperative routing algorithms,namely,relay-by-ﬂooding,relay-assisted routing,and relay-enhanced routing.Most of the existing cooperation-based routing algorithms are implemented byﬁnding a shortest-path routeﬁrst.Since the cooperative route is based on the shortest-path one,these routing algorithms do not fully exploit the merits of cooper-ative communications at the physical layer.This is our main motivation to propose a cooperation-based routing algorithm that takes into consideration the effect of the cooperative communications while constructing the minimum-power route. In this paper,we consider the minimum-power routing prob-lem with cooperation in wireless networks.The optimum route is deﬁned as the route that requires the minimum transmitted power while guaranteeing certain Quality of Service(QoS).The QoS is characterized by the end-to-end throughput.We derive a cooperation-based link cost formula,which represents the minimum transmitted power that is required to guarantee the desired QoS over a particular link.The main contribu-tion of this paper is the proposed cooperation-based routing algorithm,namely the Minimum Power Cooperative Routing (MPCR)algorithm,which can choose the minimum-power route while guaranteeing the desired QoS.It will be shown that the MPCR algorithm can achieve power saving of57.36% compared to the conventional shortest-path routing algorithms. Furthermore it can achieve power saving of37.64%with re-spect to the Cooperation Along the Shortest Non-Cooperative Path(CASNCP)algorithm,whichﬁnds the shortest-path route ﬁrst then it applies the cooperative communication upon the constructed route to reduce the transmitted power.The rest of the paper is organized as follows.In the next section,we formulate the minimum-power routing problem.In addition,we describe the network model and derive closed-form expressions for the minimum transmitted power per hop in Section II.We describe two cooperation-based routing algorithms in Section III.In Section IV,we show the numer-ical results for the power savings of the proposed algorithm. Finally,Section V concludes the paper.II.S YSTEM M ODEL AND L INK A NALYSISIn this section,we describe the network model and formulate the minimum-power routing problem.Then,we present the di-rect transmission and cooperative transmission modes.Finally, we derive the required power for these two transmission modes in order to achieve certain throughput.work ModelWe consider a graph G(N,E)with N nodes and E edges. Given any source-destination pair(S,D)∈{1,...,N},the goal is toﬁnd the S−D route that minimizes the total transmitted power,while satisfying a speciﬁc throughput.For a given source-destination pair,denoteΩas the set of all possible routes,where each route is deﬁned as a set consisting of its hops.For a routeω∈Ω,denoteωi as the i-th hop of this route.Thus,the problem can be formulated asmin ω∈Ωωi∈ωPωis.t.ηω≥ηo,(1)where Pωi denotes the transmitted power over the i-th hop,ηωis the end-to-end throughput,andηo represents the minimumdesired value of the end-to-end throughput.Letηωi denote thethroughput of the i-th hop,which is deﬁned as the number of successfully transmitted bits per second per hertz(b/s/Hz)of a given hop.Furthermore,the end-to-end throughput of a certain routeωis deﬁned as the minimum of the throughput values of the hops constituting this route,i.e.,ηω=minωi∈ωηωi.(2)It has been proven in[13]that the Minimum Energy Cooperative Path(MECP)routing problem,i.e.,toﬁnd the minimum-energy route using cooperative radio transmission,isDTFig.1.Cooperative Transmission(CT)and Direct Transmission(DT)modes as building blocks for any route.NP-complete.This is due to the fact that the optimal path could be a combination of cooperative transmissions and broadcast transmissions.Therefore,we consider two types of building blocks:direct transmission(DT)and cooperative transmission (CT)building blocks.In Fig.1the DT block is represented by the link(i,j),where node i is the sender and node j is the receiver.In addition,the CT block is represented by the links (x,y),(x,z),and(y,z),where node x is the sender,node y is a relay,and node z is the receiver.The route can be considered as a cascade of any number of these two building blocks,and the total power of the route is the summation of the transmitted powers along the route.Thus,the minimization problem in(1) can be solved by applying any distributed shortest-path routing algorithm such as the Bellman-Ford algorithm[16].B.Direct and Cooperative Transmission ModesLet h u,v,d u,v,and n u,v represent the channel coefﬁcient, length,and additive noise of the link(u,v),respectively.For the direct transmission between node i and node j,the received symbol can be modeled asr D i,j=P D d−αi,jh i,j s+n i,j,(3) where P D is the transmitted power in the direct transmission mode,αis the path loss exponent,and s is the transmitted symbol.For the cooperative transmission,we consider a modiﬁed version of the decode-and-forward incremental relaying coop-erative scheme,proposed in[3].The transmission scheme for a sender x,a relay y,and a receiver z,can be described as follows.The sender sends its symbol in the current time slot. Due to the broadcast nature of the wireless medium,both the receiver and the relay receive noisy versions of the transmitted symbol.The received symbols at the receiver and the relay can be modeled asr C x,z=P C d−αx,zh x,z s+n x,z,(4) andr C x,y=P C d−αx,yh x,y s+n x,y,(5) respectively,where P C is the source transmitted power in the cooperative transmission mode.Once the symbol is received,the receiver and the relay decode it.We assume that the relay and the receiver decide that the received symbol is correctly received if the received signal-to-noise ratio(SNR)is greater than a certain threshold, which depends on the transmitter and the receiver structures. Such system suffers from error propagation but its effect can be neglected.The rationale behind this is that when the relays operate in a high SNR regime,the dominant source of error isthe channel being in outage,i.e.,deep fade,which corresponds to the SNR falling below some threshold.This result has been proven in [17].If the receiver decodes the symbol correctly,then it sends an acknowledgment (ACK)to the sender and the relay to conﬁrm a correct reception.Otherwise,it sends a negative acknowledgment (NACK)that allows the relay,if it received the symbol correctly,to transmit this symbol to the receiver in the next time slot.This model represents a modiﬁed form of the Automatic Repeat Request (ARQ),where the relay retransmits the data instead of the sender,if necessary.The received symbol at the receiver can be written asr Cy,z =P C d −αy,z h y,z s +n y,z .(6)In general,the relay can transmit with a power that is differentfrom the sender power P C .However,this complicates the problem of ﬁnding the minimum-power formula,as will be derived later.For simplicity,we consider that both the sender and the relay send their data employing the same power P C .In this paper,ﬂat quasi-static fading channels are con-sidered,hence,the channel coefﬁcients are assumed to be constant during a complete frame,and may vary from a frame to another.We assume that all the channel terms are independent complex Gaussian random variables with zero mean and unit variance.Finally,the noise terms are modeled as zero-mean,complex Gaussian random variables with equal variance N 0.C.Link Cost FormulationSince the throughput is a continuous monotonously-increasing function of the transmission power,the optimization problem in (1)has the minimum when ηω=ηo ,∀ω∈Ω.Since the end-to-end throughput ηω=min ωi ∈ωηωi ,then the optimum power allocation,which achieves a desired throughput ηo along the route ω,forces the throughput at all the hops ηωi to be equal to the desired one,i.e.,ηωi =ηo ,∀ωi ∈ω.(7)Thisresult can be explained as follows.LetP ∗ω1,P ∗ω2,···,P ∗ωnrepresent the required powers on a route consisting of n hops,where P ∗ωiresults in ηωi =ηo for i =1,···,n .If we increase the power of the i-th blockto P ωi >P ∗ωithen the resulting throughput of the i-th block increases,i.e.ηωi >ηo ,while the end-to-end throughput does not change as min ωi ∈ωηωi =ηo .Therefore,no need to increase the throughput of any hop over ηo ,which is indicated in (7).Since the throughput of a given link ωi is deﬁned as the number of successfully transmitted bits per second per hertz,thus it can be calculated asηωi =p S ωi ×R ωi ,(8)where p S ωi and R ωi denote the per-link probability of success and transmission rate,respectively.We assume that the desired throughput can be factorized asηo =p S ×R o ,(9)where p S o and R o denote the desired per-link probability ofsuccess and transmission rate,respectively.In the sequel,we calculate the required transmitted power in order to achieve the desired per-link probability of success and transmission rate for both the direct and cooperative transmission modes.We note that the channel gain |h u,v |2between any two nodes u and v ,is exponentially distributed with parameter one [18].For the direct transmission mode in (3),the mutual infor-mation between sender i and receiver j can be given byI i,j =log1+P D d −αi,j |h i,j |2N 0.(10)Without loss of generality,we have assumed unit bandwidth in (10).The outage probability is deﬁned as the probability that the mutual information is less than the required transmission rate R o .Thus,the outage probability of the link (i,j )is calculated asp Oi,j =Pr(I i,j ≤R o )=1−exp −(2R o −1)N 0d αi,j P o.(11)If an outage occurs,the data is considered lost.The probabilityof success is calculated as p S i,j =1−p Oi,j .Thus,to achieve the desired p S o and R o for direct transmission mode,the required transmitted power isP D=(2R o −1)N 0d αi,j−log(p o ).(12)For the cooperative transmission mode,the total outage probability is given byp O x,y,z=Pr(I x,z ≤R C )·Pr(I x,y ≤R C )+Pr(I x,z ≤R C )×1−Pr(I x,y ≤R C ) ×Pr(I y,z ≤R C ),(13)where R C denotes the transmission rate for each time slot.In (13),the ﬁrst term corresponds to the event when both the sender-receiver and the sender-relay channels are in outage,and the second term corresponds to the event when both the sender-receiver and relay-receiver channels are in outage but the sender-relay is not.Consequently,the probability of success of the cooperative transmission mode can be calculated asp S =exp −g d αx,z +exp −g (d αx,y +d αy,z) −exp −g (d αx,y +d αy,z +d αx,z ) ,(14)whereg =(2R C−1)N 0P .(15)In (13)and (14),we assume that the receiver decodes the signals received from the relay either at the ﬁrst time slot or at the second time slot,instead of combining the received signals together.In general,Maximum Ratio Combining (MRC)[19]at the receiver gives a better result.However,it requires the receiver to store an analog version of the received data from the sender,which is not practical.The probability that the source transmits only,denoted by Pr(φ),is calculated as Pr(φ)=1−Pr(I x,z ≤R C )+Pr(I x,z ≤R C )Pr(I x,y ≤R C )=1−exp −g d αx,y +exp −g (d αx,y +d αx,z ) ,(16)where the term 1−Pr(I x,z ≤R C )corresponds to the event when the sender-receiver channel is not in outage,while the other term corresponds to the event when both the sender-receiver and the sender-relay channels are in outage.The probability that the relay cooperates with the source is calculated asPr(φ)=1−Pr(φ).(17)Thus,the average transmission rate of the cooperative trans-mission mode can be calculated asR =R C·Pr(φ)+R C 2·Pr(φ)=R C 21+Pr(φ) ,(18)where R C corresponds to the transmission rate if the sender is sending alone in one time slot and R C /2corresponds to the transmission rate if the relay cooperates with the sender in the consecutive time slot.We set the probability of success in (14)as p S =p S o and the average transmission rate in (18)as R =R o .By approximating the exponential functions in (14)as exp(−x )≈1−x +x 2/2,we obtaing ≈1−p S od eq,(19)where d eq =d αx,z (d αx,y +d αy,z).Thus,R C can be obtained using (18)asR C =2R o 1+Pr(φ)≈2R o 2−exp − 1−p S o d eq d αx,y +exp − 1−p S o d eq (d αx,y +d αx,z ),(20)where we substituted (19)in (16).In addition,the required power per link can be calculated using (15)and (19)as P C ≈(2R C −1)N 0d eq1−p S o .(21)Finally,the average transmitted power of the cooperative transmission can be calculated asP C avg =P C ·Pr(φ)+2P C ·Pr(φ)=P C2−Pr(φ) ,(22)where Pr(φ)and P C are given in (16)and (21),respectively.III.C OOPERATION -B ASED R OUTING A LGORITHMS In this section,we propose two cooperation-based routing algorithms,which require polynomial complexity to ﬁnd the minimum-power route.We assume that each node broad-casts periodically HELLO packet to its neighbors to update the topology information.In addition,we consider a simple Medium Access Control (MAC)protocol,which is the conven-tional Time Division Multiple Access (TDMA)scheme with equal time slots.First,we describe the proposed MPCR algorithm for a wireless network of N nodes.The MPCR algorithm can be distributively implemented by the Bellman-Ford shortest path TABLE I MPCR Algorithm.Step 1Each node x ∈{1,...,N }behaving as a sender calcu-lates the cost of the its outgoing link (x,z ),where z ∈N (x )isthe receiver as follows.For each other node y ∈N (x ),y =z ,node x calculates the cost of the cooperative transmission in (22)employing node y as a relay.Step 2The cost of the (x,z )-th link is the minimum cost among all the costs obtained in Step 1.Step 3If the minimum cost corresponds to a certain relay y ∗,node x employs this relay to help the transmission over that hop.Otherwise,it uses the direct transmission over this hop.algorithm [16].The derived power formulas for direct trans-mission and cooperative transmission are utilized to construct the minimum-power route.In the Bellman-Ford shortest path algorithm,each node i ∈{1,...,N }executes the iteration D i =min j ∈N (i )(d αi,j +D j ),where N (i )denotes the set of neighboring nodes of node i and D j represents the latest estimate of the shortest path from node j to the destination [16],which is included in the HELLO packet.Therefore,the MPCR algorithm is implemented by letting each node calcu-late the costs of its outgoing links then apply the Bellman-Ford algorithm.Table I describes the MPCR algorithm in details.The worst-case computational complexity of calculating thecosts at each node is O (N 2)since it requires two nested loops,and each has the maximum length of N to calculate all the possible cooperative transmission blocks.Second,we propose a cooperation-based routing algorithm,namely,Cooperation Along the Shortest Non-Cooperative Path(CASNCP)algorithm.The CASNCP algorithm is similar to the heuristic algorithms proposed by Khandani et al.in [11]and Yang et al.in [12]as it applies cooperative communica-tions upon the shortest-path route.However,it is implementedin a different way using the proposed cooperation-based link cost formula.First,it chooses the shortest-path route then itapplies the cooperative transmission mode upon each threeconsecutive nodes in the chosen route;ﬁrst node as the sender,second node as the relay,and third node as the receiver.Table II describes the CASNCP algorithm.IV.N UMERICAL R ESULTS In this section,we present some computer simulations to illustrate the power savings of our proposed MPCR algorithm.We consider a 200×200grid,where N nodes are uniformlydistributed.The additive white Gaussian noise has varianceN 0=−70dBm.Given a certain network topology,we randomly choose a source-destination pair and apply the various routing algorithms,discussed in Section III,to choose the corresponding route.For each algorithm,we calculate the total transmitted power per route.Finally,these quantities are averaged over 1000different network topologies.First,we illustrate the effect of varying the desired through-put on the required transmitted power per route.Fig.2depicts the transmitted power per route,required by the different routing algorithms for path loss α=2and α=4.As shown,the transmitted power increases with α,which is obvious in (12),and can be shown in (22),that the transmitted power isTABLE II CASNCP Algorithm.Step 1Implement the Shortest Non-Cooperative Path (SNCP)algorithm using the distributed Bellman-Ford algorithm to choose the conventional shortest-path route ωS as follows.Each node i ∈{1,...,N }executes the iteration D i =min j ∈N (i )(d αi,j +D j ),where N (i )denotes the set of neigh-boring nodes of node i and D j represents the latest estimate of the shortest path from node j to the destination.Step 2For each three consecutive nodes on ωS ,the ﬁrst,second,and third nodesbehave as the sender,relay,and receiver,respectively,i.e.,the ﬁrst node sends its data to the third node with the help of the second node as discussed in the cooperative transmission mode.Fig.2.Required power per route versus the desired throughput for N =20nodes,N 0=−70dBm,and R d =2b/s/Hz in a 200×200grid.proportional to the distance to the power α.Since,both cases look similar with a shift in the transmitted power values,we will consider only α=4in the rest of this section as it is more appropriate to represent the wireless medium.It is shown that the SNCP algorithm,which applies the Bellman-Ford shortest-path algorithm,requires the most transmitted power per route.Applying the cooperative communication mode on each three consecutive nodes in the SNCP route results in reduction in the required transmitted power as shown in the CASNCP algorithm’s curve.Moreover,the MPCR algorithm requires the least transmitted power among the other routing algorithms.One of the major results of this paper is that the MPCR algorithm requires less transmitted power than the CASNCP algorithm.Intuitively,this result is because the MPCR ap-plies the cooperation-based link cost formula to construct the minimum-power route.On the contrary,the CASNCP algorithm ﬁrst constructs shortest-path route then it applies the cooperative communication protocol on the established route.Therefore,the CASNCP algorithm is limited to applying the cooperative-communication protocol on certain number of nodes,while the MPCR algorithm can consider any node in the network to be in the CT blocks,which constitute the route.Thus,the MPCR algorithm reduces the required transmitted power more than the CASNCP algorithm.Fig.3depicts the required transmitted power per route by the different routing algorithms for different number of nodes at p S o =0.95and ηo =1.9b/s/Hz.As shown,the required transmitted power by any routing algorithm decreases with theFig.3.Required transmitted power per route versus the number of nodes for ηo =1.9b/s/Hz and α=4in a 200×200grid.Fig.4.Power savings per route versus the number of nodes for ηo =1.9b/s/Hz and α=4in a 200×200grid.number of nodes.Intuitively,the higher the number of nodes in a ﬁxed area,the closer the nodes to each other,the lower the required transmitted power between these nodes,which results in lower required end-to-end transmitted power.We also calculate the power saving ratio as a measure of the improvement of the MPCR algorithm.The power saving of scheme 2with respect to scheme 1is deﬁned asP ower Saving =P T (Scheme 1)−P T (Scheme 2)P T (Scheme 1)%,(23)where P T (.)denotes the total transmitted power for certain scheme.Fig.4depicts the power saving of the different routing algorithms with respect to each other.The shown curves are obtained through direct substitutions of the required transmitted power by each algorithm in (23).At N =100nodes,p S o =0.95,and ηo =1.9b/s/Hz,the power savings of MPCR algorithm with respect to the SNCP and CASNCP algorithms are 57.36%and 37.64%,respectively.In addition,the power saving of the CASNCP algorithm with respect to the SNCP algorithm is 31.62%.Fig.5depicts the required transmitted power per route of the different routing algorithms with respect to the desired bandwidth efﬁciency for N =20and N =100nodes.As mentioned with respect to Fig.2,the proposed MPCR algorithm requires the least transmitted power per route.In addition,we calculate the power saving of the MPCR algo-rithm as in (23).At R o =6b/s/Hz and N =100nodes,the MPCR algorithm reduces the transmitted power by 50.22%Fig.5.Required power per route versus the desired bandwidth efﬁciency for N0=−70dBm,p Sd=0.95b/s/Hz,andα=4in a200×200grid. and41.79%with respect to the SNCP and the CASNCP algorithms,respectively.In Fig.6,the average number of hops in each route, constructed by the different routing algorithms,is shown versus the number of nodes in the network.For the cooperative transmission mode,the average number of hops is deﬁned ash C=1·Pr(φ)+2·Pr(φ)=2−Pr(φ),(24) and the average number of hops for the direct transmission mode is one.As shown,the routes constructed by either the CASNCP or the MPCR algorithms consist of number of hops that is less than the routes constructed by the SNCP algorithm. Moreover,the average number of hops increases with N as there are more available nodes in the network,which can be employed to reduce the transmitted power.In this section,we have illustrated using the numerical results the power savings of our proposed MPCR algorithm with respect to the SNCP and CASNCP algorithms.V.C ONCLUSIONSIn this paper,we have investigated the impacts of the co-operative communications on the minimum-power routing problem in wireless networks.For a given source-destination pair,the optimum route requires the minimum end-to-end transmitted power while guaranteeing certain throughput.We have proposed the MPCR algorithm,which applies the co-operative communication while constructing the route.The MPCR algorithm constructs the minimum-power route us-ing any number of the proposed cooperation-based building blocks,which require the least possible transmitted power. For comparison issues,we have also presented the CASNCP algorithm,which is similar to most of the existing cooperative routing algorithms.The CASNCP algorithmﬁrst constructs the conventional shortest-path route then applies a cooperative-communication protocol upon the established route.From the simulation results,the power savings of the MPCR algorithm with respect to the shortest-path and CASNCP algorithms are 57.36%and37.64%,respectively.R EFERENCES[1]L.M.Feeney and M.Nilsson,“Investigating the energy consumption ofa wireless network interface in an ad hoc networking environment,”inProc.of IEEE INFOCOM,Anchorage,AK,Apr.2001.Fig.6.Average number of hops per route versus the number of nodes for ηo=1.9b/s/Hz andα=4in a200×200grid.[2]T.M.Cover and A.El Gamal,“Capacity theorems for the relay channel,”IEEE .Theory,vol.25,no.5,pp.572-584,Sept.1979. [3]neman,D.N.C.Tse,and G.W.Wornell,“Cooperative diversityin wireless networks:efﬁcient protocols and outage behaviour,”IEEE rm.Theory,vol.50,pp.3062-3080,Dec.2004.[4]neman and G.W.Wornell,“Distributed space-time coded pro-tocols for exploiting cooperative diversity in wireless networks,”IEEE rm.Theory,vol.49,pp.2415-2525,Oct.2003.[5] A.Sendonaris,E.Erkip,and B.Aazhang,“User cooperation diversity-Part I:system description,”IEEE m.,vol.51,pp.1927-1938, Nov.2003.[6] A.Sendonaris,E.Erkip,and B.Aazhang,“User cooperation diversity-Part II:implementation aspects and performance analysis,”IEEE Trans.Comm.,vol.51,pp.1939-1948,Nov.2003.[7] A.S.Ibrahim,A.K.Sadek,W.Su,and K.J.Ray Liu,“Cooperative com-munications with partial channel state information:when to cooperate?,”in Proc.of IEEE Global Telecommunications Conference(Globecom’05), pp.3068-3072,vol.5,Dallas,TX,28Nov.-2Dec.2005.[8] A.S.Ibrahim,A.K.Sadek,W.Su,and K.J.Ray Liu,“Relay Selec-tion in multi-node cooperative communications:When to cooperate and whom to cooperate with?,”in Proc.of IEEE Global Telecommunications Conference(Globecom’06),San Francisco,CA,Nov.2006.[9] A.K.Sadek,W.Su,and K.J.Ray Liu,“A class of cooperativecommunication protocols for multi-node wireless networks”,in Proc.of IEEE International Workshop on Signal Processing Advances in Wireless Communications(SPAWC’05),pp.560-564,New York,NJ,June2005.[10] A.K.Sadek,Z.Han,and K.J.Ray Liu,“A distributed relay-assignmentalgorithm for cooperative communications in wireless networks”,in Proc.of IEEE International Conference on Communications,Istanbul,Turkey, June2006.[11] A.E.Khandani,E.Modiano,L.Zheng,and J.Abounadi,“Cooperativerouting in wireless networks,”Chapter in Advances in Pervasive Comput-ing and Networking,Kluwer Academic Publishers,Eds.B.K.Szymanski and B.Yener,2004.[12]Z.Yang,J.Liu,and A.Host-Madsen,“Cooperative routing and powerallocation in ad-hoc networks,”in Proc.of IEEE Global Telecommunica-tion Conference,Globecom,Dallas,TX,Nov.2005.[13] F.Li,K.Wu,and A.Lippman,“Energy-efﬁcient cooperative routingin multi-hop wireless ad hoc networks,”in Proc.of IEEE International Performance,Computing,and Communications Conference,pp.215-222,Phoenix,AZ,Apr.2006.[14]M.Sikora,neman,M.Haenggi,D.J.Costello,and T.E.Fuja,“Bandwidth-and power-efﬁcient routing in linear wireless networks,”IEEE rm.Theory,vol.52,pp.2624-2633,Jun.2006.[15]J.Luo,R.S.Blum,L.J.Greenstein,L.J.Cimini,and A.M.Haimovich,“New approaches for cooperative use of multiple antennas in ad hoc wire-less networks,”in Proc.of IEEE60th Vehicular Technology Conference, vol.4,pp.2769-2773,Los Angels,CA,Sept.2004.[16] D.Bertsekas and R.Gallager,Data networks,2nd ed.,Prentice Hall,1991.[17]L.Zheng and D.N.C.Tse,“Diversity and multiplexing:a fundamentaltradeoff in multiple-antenna channels,”IEEE Trans.on Info.Theory,vol.49,pp.1073-1096,May2003.[18]J.G.Proakis,Digital communications,4th ed.,McGraw-Hill,2000.[19] D.G.Brennan,“Linear diversity combining techniques,”Proceedingsof the IEEE,vol.91,no.2,pp.331-356,Feb.2003.。

Ad hoc路由算法(文献综述)

Ad-hoc路由算法1 前言为满足信息社会对资源共享及信息传递的需求，计算机网络技术和无线通讯技术在近几十年得到了极大的发展。

20世纪50年代诞生的利用导线传输数据的有线网络经过几十年的发展，从双绞线、同轴电缆发展到如今的光纤通讯网络，网络的性能和覆盖范围虽然得到了很大的提升但是仍然无法满足人们在移动场景中对网络接入的需求。

在一些场合如抢险救灾、数字化战场、野外勘探及临时会议等场合无法快速高效的建立这常用无线网络，因此需要一种新型网络满足这些应用需求。

为满足在上述场合下快速高效组网的需求，无需基础设施的移动自组织网络（Mobile Ad-hoc Network）应用而生[2]。

Ad Hoc网络是一种不需要任何基站或固定基础设施的多跳无线网络，具有独立组网、自组织、动态拓扑、无约束移动、多跳路由等众多特点，能够快速地布设局部通信网络。

近年来，Ad Hoc网络研究得到了很大的发展，尤其是对网络路由协议的研究已经逐步成熟。

自二十世纪七十年代开始，由美国国防部所属的国防先进研究项目局推动了移动自组织网络方面最初的研究项目“战场环境中的数据包无线网络”（Packet Radio Networking），并在此后对多项相关研究进行支持。

最初由军方推动的移动自组织网主要应用在军事领域，然而随着微电子技术、嵌入式系统技术、无线通信技术等的发展和相关硬件成本的降低，移动自组织网络技术开始在民用领域推广[1]。

尤其在近十年，一些新技术与移动自组织网络的结合产生了许多新的研究热点如无线传感网络（Wirless Sensor Network）、车载自组网（Vehicular Ad hoc Network）、无线个人局域网（Wireless Personal Area Networks）以及无线Mesh网（Wireless Mesh Network）等[5]。

2 正文2.1、Ad-hoc网络的优点（1）无中心Ad hoc网络没有严格的控制中心。

基于蚁群算法的网络路由最优路径判断模块设计与实现

基于蚁群算法的网络路由最优路径判断模块设计与实现徐虹;杨雅志;赵明【摘要】网络中节点的能量是有限的，网络拓扑结构具有波动性，导致传统网络路由算法不能有效适应这些变化，自组织性较差，无法及时获取最优路径，大大降低网络性能。

因此，设计基于蚁群算法的网络路由最优路径判断模块。

其以FPGA 为控制核心实现硬件设计，具体包括控制模块、存储器模块、寻求后续节点集模块、采集后续节点模块、状态调整模块、信息素调整模块和最优路径判断模块。

模块实现部分给出了蚁群算法的核心代码。

实验结果表明，所设计的最优路径判断模块具有较高的收敛速率，获取的路径更短，能够延长网络的运行周期。

%Since energy in the network node is limited,and the network topology has volatility,which cause that the tradi⁃tional network routing algorithm can not effectively adapt to these changes,the self⁃organizing is poor,the optimal path can not be got timely,and the network performance is reduced greatly,the optimal path judgment module based on ant colony algorithm for network routing is designed. The FPGA as the control core is used to realize the hardware design,including the control module, memory module,subsequent nodes set seeking module,subsequent node acquisition module,state adjustment module,informa⁃tion adjustment module,optimal path judgment module and multiplex selection module. The core code of ant colony algorithm is presented in the process of module implementation. The experimental result shows that the designed optimal path judgment module has high⁃speed convergence and shorter access path,and can lengthen the operation cycle of the network.【期刊名称】《现代电子技术》【年(卷),期】2017(040)004【总页数】4页(P36-38,43)【关键词】蚁群算法;网络路由;最优路径;FPGA【作者】徐虹;杨雅志;赵明【作者单位】成都工业学院信息与计算科学系，四川成都 611730;成都工业学院信息与计算科学系，四川成都 611730;成都工业学院信息与计算科学系，四川成都 611730【正文语种】中文【中图分类】TN711-34;TP393无线传感器网络（WSN）通常是由传感器节点构成的自组织网络，在军事、医疗、工业等领域应用广泛。

《计算机网络》中英词汇对照表

《计算机网络》中英文对照表Chapter 11.1Internet：因特网Computer network ：计算机网络Host: 主机End system: 终端系统Packet switching: 分组交换Route: 路径Internet service provider (ISP): 因特网服务提供商Protocol: 协议Transmission Control Protocol (TCP)：传输控制协议1.2Client: 客户端Server: 服务器Peer: 对等机Reliable data transfer: 可靠数据传输Flow control: 流量控制Congestion-control: 拥塞控制User Datagram Protocol (UDP): 用户数据报协议1.3Circuit switching: 电路交换/线路交换Packet switching: 分组交换Frequency-division multiplexing (FDM): 频分多路复用Time-division multiplexing (TDM): 时分多路复用Bandwidth: 带宽Time slot: 时隙Frame: 帧Message: 报文:Packet: 分组Store-and-forward: 存储转发Datagram network: 数据报网络Virtual-circuit network: 虚电路网络1.4Router: 路由器Modem: 调制解调器Local area network (LAN): 局域网Ethernet: 以太网Wireless LAN: 无线局域网Guided media: 导向型介质Unguided media: 非导向型介质Twisted-pair copper wire: 双绞线Unshielded twisted pair(UTP): 非屏蔽双绞线Coaxial cable: 同轴电缆Fiber optics: 光线/光缆1.6Nodal processing delay: 结点处理延迟Queuing delay: 排队延迟Transmission delay: 发送延迟Propagation delay: 传播延迟Traffic intensity: 流通强度End-to-end delay: 端到端延迟1.7Layer: 层次Protocol stack: 协议栈Application layer: 应用层Transport layer: 传输层Network layer: 网络层Link layer: 链路层Physical layer: 物理层Encapsulation: 封装Message: 报文Segment: 报文段Datagram: 数据报Frame: 帧Chapter 22.1Client-server architecture: 客户端－服务器体系结构；C/S结构P2P architecture: 对等结构Processes: 进程Socket: 套接字Application programming interface (API): 应用程序编程接口IP address: IP地址Prot number: 端口号Syntax: 语法Semantics: 语义Full-duplex: 全双工Handshaking: 握手Real-time application: 实时应用2.2The World Wide Web: 万维网HyperText Transfer Protocol (HTTP): 超文本传输协议Web page: 网页Object: 对象HyperText Markup Language (HTML): 超文本标记语言URL：统一资源定位符Browser: 浏览器Persistent connection: 持久连接Non-persistent connection: 非持久连接Round-trip time (RTT): 往返时间Without pipelining: 非流水线方式With pipelining: 流水线方式Web cache: web 缓存Proxy server: 代理服务器2.3File Transfer Protocol (FTP): 文件传输协议Control connection: 控制连接Data connection: 数据连接Out-of-band: 带外In-band: 带内2.4Electronic Mail: 电子邮件User agent: 用户代理Mail server: 邮件服务器Simple Mail Transfer Protocol (SMTP): 简单邮件传输协议Mailbox: 邮箱Multipurpose Internet Mail Extensions (MIME): 多用途因特网邮件扩展协议Post Office Protocol (POP): 邮局协议Internet Mail Access Protocol (IMAP): Internet 邮件访问协议2.5Domain Name System (DNS): 域名系统Hostname: 主机名Host aliasing: 主机别名Mail server aliasing: 邮件服务器别名Load distribution: 负载分配Root DNS server: 根DNS服务器Top-Level Domain (TLD) servers: 顶级域DNS服务器Authoritative DNS servers: 授权DNS服务器；权威DNS服务器Local DNS server: 本地DNS服务器Database: 数据库Chapter 33.1Logical communication: 逻辑通讯3.2Multiplexing: 多路复用Demultiplexing: 多路分解Well-known port number: 众所周知的端口号3.3UDP segment: UDP报文段Checksum: 校验和；检查和Wrapped around: 回卷3.4Channel: 通道；信道Positive acknowledgement : 肯定应答Negative acknowledgement: 否定应答ARQ （automatic repeat request）: 自动重传请求Feedback: 反馈Retransmission: 重传Stop-and-wait protocol: 停止－等待协议Duplicate packets: 冗余分组Sequence number: 顺序号Timer: 定时器Alternating-bit protocol: 比特交替协议Utilization: 利用率Go-back-N (GBN): 回退N步Window size: 窗口大小Sliding-window protocol: 滑动窗口协议Cumulative acknowledgement: 累积确认Timeout: 超时Selective Repeat (SR): 选择重传3.5Connection-oriented: 面向连接Point-to-point: 点到点Three-way handshake: 三次握手Maximum segment size (MSS): 最大报文段大小Maximum transmission unit (MTU): 最大传输单元Piggybacked: 捎带Sample RTT: 样本RTTFast retransmit: 快速重传Selective acknowledgement: 选择确认Flow-control: 流量控制Receive window: 接收窗口3.7Congestion control: 拥塞窗口Self-clocking: 自定时的Additive-increase, multiplicative-decrease: 加性增，乘性减Slow star: 慢启动Congestion avoidance: 拥塞避免Threshold: 阈值Fast recovery: 快速恢复Bottleneck: 瓶颈Latency: 延迟Chapter 44.1Forwarding: 转发Routing: 路由Routing algorithm: 路由算法Forwarding table: 转发表Router: 路由器Jitter: 抖动Best-effort service: 尽力而为的服务4.2Virtual-circuit (VC) network: 虚电路网络Datagram network: 数据报网络Prefix: 前缀Longest prefix matching rule: 最长前缀匹配规则4.3Input port: 输入端口Switching fabric: 交换结构Routing processor: 路由处理器Crossbar: 交叉结构4.4Time-to-live (TTL) :生存时间Fragmentation: 分片；片段Dotted-decimal notation: 点分十进制表示法Subnet: 子网Subnet mask: 子网掩码Classless Interdomain Routing (CIDR): 无类别域际路由选择Dynamic Host Configuration Protocol（DHCP）：动态主机配置协议Plug-and-play: 即插即用Network address translation (NA T): 网络地址转换Internet Control Message Protocol (ICMP): 因特网控制报文协议Dual-stack: 双栈Tunneling: 隧道4.5Default router: 默认路由器Graph: 图A global routing algorithm : 全局路由算法A decentralized routing algorithm : 分布式路由算法Static routing algorithm: 静态路由算法Dynamic routing algorithm : 动态路由算法Link-State (LS): 链路状态Distance-Vector(DV): 距离向量Routing table: 路由表Autonomous system (AS): 自治系统Intra-autonomous system routing protocol: 自治系统内路由协议Inter-AS routing protocol: 自治系统间路由协议4.6Interior gateway protocol: 内部网关协议Routing Information Protocol (RIP): 路由信息协议Open Shortest Path First (OSPF): 开放最短路径优先协议Advertisement: 公告Hop: 跳Border Gateway Protocol (BGP): 边界网关协议4.7Broadcast: 广播Multicast: 多播Chapter 55.1Node: 结点Link: 链路Frame: 帧Medium access control (MAC): 介质访问控制Full-duplex: 全双工Half-duplex: 半双工Adapter: 适配器Network interface card (NIC): 网卡Interface: 接口5.2Parity check: 奇偶校验Odd: 奇数Even: 偶数Cyclic redundancy check (CRC): 循环冗余校验Polynomial: 多项式5.3Collide: 冲突Multiple access protocol: 多路访问协议Channel partitioning protocol: 信道划分协议Random access protocol: 随机访问协议Taking-turns protocol: 轮转协议Code division multiple access (CDMA): 码分多址访问Carrier sensing: 载波侦听Collision detection: 冲突检测Polling protocol: 轮询协议Token-passing protocol: 令牌传递协议Token: 令牌Local Area Network (LAN): 局域网Token-ring: 令牌环Fiber distributed data interface (FDDI): 光纤分布式数据接口Metropolitan Area Network (MAN): 城域网5.4Address Resolution Protocol (ARP): 地址解析协议Dynamic Host Configuration Protocol (DHCP): 动态主机配置协议5.5Ethernet: 以太网Preamble: 前导码Manchester encoding: 曼彻斯特编码5.6Hub: 集线器Collision domain: 冲突域Switch: 交换机Filtering: 过滤Forwarding: 转发Switch table: 交换表Self-learning: 自学习Plug-and-play devices: 即插即用设备Cut-through switching: 直通式交换5.7Point-to-point: (PPP): 点到点。

ERouting Final Exam CCNA Exploration路由协议和概念答案

ERouting Final Exam-CCNA Exploration:路由协议和概念(Version4.0)1.Which of the following are required when adding a network to the OSPF routing process configuration?network addressloopback addressa utonomous system numbersubnet maskwildcard maskarea ID2.Which of the following are primary functions of a router?(Choose two.)packet switchingmicrosegmentationdomain name resolutionpath selectionflow control3.Refer to the exhibit.When troubleshooting a network,it is important to interpret the output of various router commands.On the basis of the exhibit,which three statements are true?(Choose three.)The missing information for Blank1is the command show ip route.The missing information for Blank 1 is the command debug ip route.The missing information for Blank 2 is the number 100.The missing information for Blank2is the number120.The missing information for Blank 3 is the letter R.The missing information for Blank3is the letter C.4.Refer to the exhibit.Packets destined to which two networks will require the router to perform a recursive lookup?(Choose two.)10.0.0.0/864.100.0.0/16128.107.0.0/16172.16.40.0/24192.168.1.0/24192.168.2.0/245.When would the network administrator use the ip bandwidth-percent eigrp as-number percent command?when there is a low bandwidth connectionwhen the connection is on a shared mediumwhen the connection is serial instead of Ethernetwhen the link is always busy6.Refer to the exhibit.Cost for each path are shown.If all routers are configured to use OSPF,what would be the path of a packet sent from Router C to Router D if Router A was down?C-B-E-DC-B-A-D C-F-E-DC-F-B-A-D C-F-E-A-D7.What OSPF packet type is used to elect the designated router(DR)and backup designated router(BDR)on multiaccess networks?helloLSULSRDBDLSAck8.Refer to the exhibit.The hosts on the R1LAN are unable to access the Internet.What is incorrectly configured?the IP address of the Fa0/0 interface at R1the IP address of the S0/0/1 interface at R2the IP address of the S0/0/0interface at R1the subnet mask of the S0/0/1 interface at R29.Refer to the exhibit.Which summarization should R1use to advertise its networks to R2? 192.168.1.0/24192.168.0.0/24192.168.0.0/22192.168.1.0/2210.Refer to the exhibit.What are two of the routes added to the routing table of R1? (Choose two.)R 172.16.1.0/24 [120/1] via 192.168.3.0, 00:00:24, Serial0/0/0R192.168.1.0/24[120/1]via172.16.2.1,00:00:24,Serial0/0/1R 192.168.9.0/24 [120/1] via 172.16.1.2, 00:00:24, Serial0/0/0R192.168.100.0/24[120/1]via172.16.1.1,00:00:24,Serial0/0/0R 192.168.2.0/24 [120/1] via 172.16.1.2, 00:00:24, Serial0/0/011.A router boots and enters setup mode.What is the reason for this?The IOS image is corrupt.Cisco IOS is missing from flash memory.The configuration file is missing from NVRAM.The POST process has detected hardware failure.12.Refer to the exhibit.A router learns a route to the192.168.6.0network,as shown in the output of the show ip rip database command.However,upon running the show ip routecommand,the network administrator sees that the router has installed a different route to the192.168.6.0network learned via EIGRP.What could be the reason for the missing RIP route?Compared to RIP,EIGRP has a lower administrative distance.Compared to EIGRP, RIP has a higher metric value for the route.Compared to RIP, the EIGRP route has fewer hops.Compared to RIP, EIGRP has a faster update timer.13.All routers in a network are configured in a single OSPF area with the same priority value.No loopback interface has been set on any of the routers.Which secondary value will the routers use to determine the router ID?The highest MAC address among the active interfaces of the network will be used.There will be no router ID until a loopback interface is configured.The highest IP address among the active FastEthernet interfaces that are running OSPF will be used.The highest IP address among the active interfaces will be used.14.Refer to the exhibit.Routers R1and R2are directly connected via their serial interfaces and are both running the EIGRP routing protocol.R1and R2can ping the directly connected serial interface of their neighbor,but they cannot form an EIGRP neighbor adjacency.What action should be taken to solve this problem?Enable the serial interfaces of both routers.Configure EIGRP to send periodic updates.Configure the same hello interval between the routers. Configure both routers with the same EIGRP process ID.15.Refer to the exhibit.The interfaces of all routers are configured for OSPF area0.R3can ping R1,but the two routers are unable to establish a neighbor adjacency.What should the network administrator do to troubleshoot this problem?Check if the interfaces of the routers are enabled.Check the hello and dead intervals between the routers.Check the process ID of both routers.Check if CDP is enabled on all the routers.16.Refer to the exhibit.The hosts that are connected to R2are unable to ping the hosts that are connected to R1.How can this problem be resolved?Configure the router ID on both routers.Configure the R2router interfaces for area0.Configure a loopback interface on both routers.Configure the proper subnet masks on the router interfaces.17.Refer to the exhibit.The command ip route0.0.0.00.0.0.0S0/0/0is run on router R2. What are the two results of this command?(Choose two.)A static route will be updated in the routing table.The traffic from the Internet will be directed to R2.The traffic from the source network 172.16.0.0/22 will be blocked.The route will be specified as the default route for all networks not defined in the routing table.All the broadcasts will be forwarded via the S0/0/0 interface of R2.18.Refer to the exhibit.All routers are properly configured with default configurations and are running the OSPF routing protocol.The network is fully converged.A host on the 192.168.3.0/24network is communicating with a host on the192.168.2.0/24network.Which path will be used to transmit the data?The data will be transmitted via R3-R2.The data will be transmitted via R3-R1-R2.The traffic will be load-balanced between two paths — one via R3-R2, and the other via R3-R1-R2.The data will be transmitted via R3-R2, and the other path via R3-R1-R2 will be retained as the backup path.19.Refer to the exhibit.What is the meaning of the highlighted value120?It is the metric that is calculated by the routing protocol.It is the value that is used by the DUAL algorithm to determine the bandwidth for the link.It is the administrative distance of the routing protocol.It is the hold-down time, measured in seconds, before the next update.20.In a complex lab test environment,a router has discovered four paths to192.168.1.0/24 via the use of the RIP routing process.Which route will be installed in the routing table after the discovery of all four paths?R 192.168.1.0/24 [120/3] via 192.168.110.1, 00:00:17, Serial0/1/0R 192.168.1.0/24 [120/2] via 192.168.200.1, 00:00:17, Serial0/0/0R192.168.1.0/24[120/1]via192.168.100.1,00:00:17,Serial0/0/1R 192.168.1.0/24 [120/4] via 192.168.101.1, 00:00:17, Serial0/1/121.Refer to the exhibit.PC1is unable to access the Internet.What is the cause of the problem?An incorrect IP address is configured between the two routers. No static route is configured on Router2.A routing loop has occurred.No routing protocol is configured on either of the two routers.22.How does route poisoning prevent routing loops?New routing updates are ignored until the network has converged.Failed routes are advertised with a metric of infinity.A route is marked as unavailable when its Time to Live is exceeded.The unreachable route is cleared from the routing table after the invalid timer expires.23.Which statement is true about the metrics used by routing protocols?A metric is a value used by a particular routing protocol to compare paths to remote networks.A common metric is used by all routing protocols.The metric with the highest value is installed in the routing table.The router may use only one parameter at a time to calculate the metric.24.Which statement correctly describes a feature of RIP?RIP is a link-state routing protocol.RIP uses only one metric—hop count—for path selection.Advertised routes with hop counts greater than 10 are unreachable.Messages are broadcast every 10 seconds.25.Refer to the exhibit.OSPF is used for the routing protocol and all interfaces are configured with the correct IP addresses and subnet masks.During testing,it is found that router R1is unable to form an adjacency with R2.What is the cause of this problem?Both routers have been configured with incorrect router IDs.Both routers have been configured in different OSPF areas.Both routers have been configured with an incorrect network type.Both routers have been configured with different hello and dead intervals.26.A network administrator is in charge of two separate networks that share a single building.What device will be required to connect the two networks and add a common connection to the Internet that can be shared?hubrouteraccess pointEthernet switch27.Which network and mask combination requires the use of a classless addressing solution?10.32.0.0/11172.16.0.0/12192.168.0.0/24192.168.128.32/2728.A company is using static routes that are configured with an administrative distance of “1”on all routers in the network.The network administrator decides to introduce a dynamic routing protocol to reduce the manual configurations for the static routes.Which optionidentifies the correct procedure for the dynamic routing to take place in the network?The static routes and the dynamic routes will have the traffic alternate between them.The static routes will be automatically removed once the dynamic routing is configured.The static routes will be automatically updated with the next hop IP address once the dynamic routing is configured.The static routes must be manually removed from all routers in order for the dynamic routes to be installed in the routing table.29.Refer to the exhibit.Based on the partial output in the exhibit,why can users establish a console connection to this router without entering a password?The login command was not entered on the console line.The enable password should be an enable secret password.No username and password combination has been configured.Console connections cannot be configured to require users to provide passwords.30.Refer to the exhibit.When a static IP address is being configured on the host,what address should be used for the default gateway?10.1.1.110.1.1.2172.16.1.1192.168.1.131.Refer to the exhibit.The entire192.168.1.0network has been allocated to address hosts in the diagram.Utilizing VLSM with contiguous address blocks,which set of addresses andprefixes could be used to create an addressing solution with a minimum waste of IP addresses?Correct answer is image4.32.Refer to the exhibit.The network is configured for OSPF routing with default settings. The bandwidths have been configured correctly for each link.If the T1link between router A and router E fails,what path will a packet from router A take to reach the LAN attached to router F when the network has converged?A, B, C, FA, B, C, E, FA, D, G, E, FA,D,G,H,F33.Which candidate route has the longest match for a packet with a destination address of10.30.16.48?10.30.0.0/1610.30.15.0/2310.30.16.0/2410.30.16.32/2710.30.16.32/3034.Refer to the exhibit.The network is configured with RIPv2.However,network administrators notice that communication cannot be successfully completed from one LAN to another.A network administrator issues the show ip route command on the HQ router. Based on the output,what should be done to correct the problem?Disable the load balancing feature of RIPv2.Issue the no auto-summary command for RIPv2.Replace RIPv2 with EIGRP which supports VLSM.Make sure that the network statements include the correct subnet mask.35.Which multicast address does EIGRP use to send hello and updates packets?224.0.0.5224.0.0.6224.0.0.9224.0.0.1036.Refer to the exhibit.Why is the state of the serial0/0/0interface administratively down?An IP address has not been configured on the interface.The WIC was installed into the incorrect slot on the router.The default encapsulation on the interface has been modified.The no shutdown command has not been executed on the interface.37.Refer to the exhibit.How was the OSPF default gateway entry for R2determined? Default routes are automatically injected by OSPF into all advertisements.A static default gateway route is defined in the configuration of R2.The default-information originate command is applied on R1.The ISP defines the gateway of last resort and automatically passes it to R1 and R2.The ip default-gateway command is applied on R2.38.Refer to the exhibit.RIPv1has been properly configured on all routers in the network. However,users on LAN2have intermittent connectivity with the users on LAN1and LAN3. What is the cause of the problem?Both LAN networks are separated from router R2 with a variably subnetted Class C network 209.165.200.0/30.Neither router R1 nor router R3 has a static route configured that points to the variably subnetted 172.16.0.0/24 networks.Both routers R1and R3are sending the summarized172.16.0.0/16network to R2in their RIPv1routing updates.Both networks 172.16.1.0/24 and 172.16.100.0/24 are configured with a subnet mask different from the default classful mask.39.Which default EIGRP configuration must be modified to allow an EIGRP router to advertise subnets that are configured with VLSM?split horizonmetric K valuesautosummarizationhello and dead intervals40.What is a successor for a destination network in an EIGRP network?the next hop on the primary route with the largest feasible distance to the destinationthe next hop on the primary route with the smallest feasible distance to the destination41.Refer to the exhibit.Which route will be removed from the routing table if manual EIGRP summarization is disabled on the Serial0/0/0interface of Router3?0.0.0.0/0172.16.0.0/16172.16.1.0/24172.16.3.0/3042.Which port can be used for initial router configuration?AUXvty 0s0/0/0console43.Which two link-state routing protocol challenges does OSPF resolve through the election of a DR?(Choose two.)the extensive flooding of LSAs throughout the OSPF areathe excessive adjacencies when the number of routers increasesthe requirement for link-state database updates to be propagated between OSPF areasthe heavy CPU load that is imposed because each router must compute shortest paths by using the SPF algorithmthe requirement for each router to build a topological database of the internetwork to determinet he shortest paths between networks44.A routing table shows an EIGRP route to192.168.1.0/24with a metric of301440.What other term also describes this EIGRP metric value?feasible distancereported distancefeasible successorfeasibility condition45.Refer to the exhibit.The network administrator has run the following command on R1.R1(config)#ip route192.168.2.0255.255.255.0172.16.1.2What is the result of running this command?Traffic for network192.168.2.0is forwarded to172.16.1.2.This route is automatically propagated throughout the entire network.Traffic for all networks is forwarded to 172.16.1.2.The command invokes a dynamic routing protocol for 192.168.2.0.46.Refer to the exhibit.What will happen if interface Serial0/0/1goes down on Router1? The Dijkstra algorithm will calculate the feasible successor.DUAL will query neighbors for a route to network192.168.1.0.Neighbor 172.16.3.2 will be promoted to the feasible successor.Traffic destined to the 192.168.1.0 network will be dropped immediately due to lack of a feasible successor.47.Refer to the exhibit.A network administrator is accessing router R1from the console port.Once the administrator is connected to the router,which password should the administrator enter at the R1>prompt to access the privileged EXEC mode?Cisco001Cisco123Cisco789Cisco90148.Refer to the exhibit.Which option will provide the configuration that is needed for router R1to dynamically learn routes to the192.168.100.16/28,192.168.100.32/28,and 192.168.100.48/28subnetworks?with static routeswith a routed protocolwith a routing protocolwith directly connected routes49.Refer to the exhibit.What will happen when the router reloads?It will boot into ROMMON mode.It will ignore the start-up configuration file.It will look for the start-up configuration file on the TFTP server.It will attempt to load the start-up configuration file that is stored in NVRAM.50.On a router,which actions can be performed in user mode?perform password recoverymake global configuration changesview status of various router functionsmake changes to a specified interface。

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September 2011, 18(Suppl. 1): 48–52/science/journal/10058885 The Journal of China Universities of Posts and TelecommunicationsDynamic routing network algorithm of low voltagebased on link qualityLI Jie ( ), ZHOU Ming, SONG Jun-deSchool of Computer Science, Beijing University of Posts and Telecommunications, Beijing 100876, ChinaAbstractPower distribution network is a dedicated transmission network for power. If you want to use it as communication network, the network traffic will become very complicated. Low voltage distribution network topology is very complex and quite different in different distribution network; and different load leave or input power line will cause a strong performance of channel variability. It is because of these features of low voltage distribution network that it difficult to networking and the network is easily destroyed. This paper presents a dynamic routing algorithm, based on link quality, to improve the reliability of low voltage distribution networks. The algorithm can eventually form an 8-layer structure of the tree topology, and can achieve network self-healing capabilities when the link is broken. The algorithm is suitable for a variety of network physical topology, and finally be able to form a tree structure, thus effectively improving the reliability and system flexibility of communication network. Through the simulation on NS2, we can see the feasibility and network self-healing of the algorithm.Keywords PLC network, self-healing, link quality1 IntroductionCommunication technology is becoming more and more widely in the field of distribution network. Through the PLC (power line communication) technology, we can run the distribution network for monitoring and associated control, such as: we can use it to control street lighting, automatic meter reading and remote monitoring, etc. This shows that power line network communication has very broad prospect [1–4]. The traditional methods of improving the reliability of PLC networks include increasing the transmission power, optimizing the coupling devices. Increasing the transmission power should not be used, mainly because of its development in the opposite direction with PLC. And we can optimize the coupling device to prevent the channel attenuation, but impedance characteristics of the low power voltage distribution networks are time-varying [5]. Through a large number of experiments in PLC, the dynamic routing algorithm to select the relay nodes methods, in order toReceived date: 25-07-2011Corresponding author: LI Jie, E-mail: jli@ DOI: 10.1016/S1005-8885(10)60211-7improve the reliability of power line communication, is feasible measures. Relay nodes and common nodes are identical, and the relay node is only added dynamic routing in software, which can adapt to the characteristics of changes in network [6–7]. In view of this, a dynamic group routing algorithm [8–10] to improve the communication reliability is proposed. Firstly, the node who wants to join the network broadcast a packet to get the link quality around it, and then select the best signal quality as its parent node in the network, notify the NC node of join information. At last, the NC node will assigned a node ID and network ID to the node who wants to join in the network.2 Protocol descriptionThe resulting network topology is tree structure, which includes the NC node and RS (remote station) [11–13].The network has a total of eight levels, in which 0 level has only one node (concentrator NC), the other levels can have 256 nodes and their child nodes, but the 7th level nodes can not have child nodes. NC node functions as a network concentrator, which is the root of the tree, since the launch ofSupplement 1 LI Jie, et al. / Dynamic routing network algorithm of low voltage based on link quality 49the NC node a logical subnet network ID will be assigned. The entire network topology is developed from the NC node. Except the NC node, the others are RS nodes.2.1 Address serviceEach node module has a MAC address provided by the manufacturer, which is a 6-byte code. However, you can not use this 6-byte code for data communications network. The MAC address is used when applying the node ID in the network. Therefore, each node in the network must have a network ID and node ID, which are obtained in the course of networking, and not be set by man [14–16] .1) Network ID service:Each logical subnet has a network ID, the network ID assigned to the NC node firstly. If a new node joins the logical subnet, the NC node will assigned the network ID to the corresponding child nodes. A new network can maintain the uniqueness of different logical subnet by choosing the unique network address.2) Node ID ServiceA node to node by node and node ID makes the link between the phase node by node ID to carry out normal communication. Node ID format is 4B of code, the first two bytes of the logical subnet of the node in which a layer, the last two bytes identify the node, the first few nodes in the layer. For example, if a node ID is 0X0102, it means that the nodes in the network's first layer of the second node.2.2 Joining of NodeThe process of the network topology formation is the process that all nodes join the network, then a tree network topology, the root of which is NC node, is formed. A network ID will be assigned to the NC node When it turns on, and the own node ID is set to 0X0000. If a node applies to join the logical subnet, the node will broadcast a link signal quality of the data packets SQP (Signal Quality Packet) to the nodes that can communicate directly, format of the packet is shown in Table 2. The node can get the signal quality between the nodes that can communicate directly. SQP packet contains a Node Filter parameter and a responsive type parameter. The new join node’s parent node can’t at the 7 level, because the top level of the network is 7.In the SQP packet, the value of Node Filter is set to 0x06FF and the response value is set to 1, which means the nodes in level 0 to 6 can respond to all nodes. The specific meaning of Node Filter parameter is shown in Table 1:Table 1 Channel quality tableValue ofNodeFilterValue of response type is 1 Value of response type is 10X0001Only the concentrator isallowed to answer the joinrequest.Only the concentrator isallowed to answer the joinrequest0X01FFOnly the concentrator and allnodes on level 1 are allowedto answer the join requestall nodes on level 1 areallowed to answer the joinrequest0X03FFOnly the concentrator and allnodes on level 1-3 areallowed to answer the joinrequestall nodes on level 3 areallowed to answer the joinrequest0X030AOnly the concentrator andthe nodes with the id 0x01 –0x0A on the levels 1-3 areallowed to answer the joinrequestthe nodes with the id 0x01–0x0A on the levels 3 areallowed to answer the joinrequest0X06FFOnly the concentrator and allnodes on level 1-6 areallowed to answer the joinrequestall nodes on level 6 areallowed to answer the joinrequestThe nodes who receive SQP data packets, through the detecting of node link quality between nodes, respectively, return link quality data packet to the nodes that want to join networks by RSQP. The format of RSQP is shown in Table 3. After the node obtain the link quality with its directly communicating nodes, select the best link quality nodes as its parent node, and establish the route to NC node, from which we can determine the parent nodes of new joining node, and sends a notification packet JNP1 to its parents. The format of JNP1 is shown in Table 4.When the parent nodes receive the join packet, it saves the MAC address of the new joining node. If the parent node is NC node, it will sent node id to the new joining node directly through SNP packet, adding the new ID to the tree network topology. Otherwise, the new joining node will send data packet (Get Node ID packet, GNP) to NC node in order to get the node ID, the format of GNP packet is shown in Table 5,which inform the NC node a new node want to join the network. The NC node determine the new joining node belongs to which level by judging the ID of sending node, and assigned a node ID to the new joining node. When all the relay nodes receive the GNP packet, they temporarily store the sending node ID, which is to establish the tree topology of relay nodes.After the NC node receives the request, it sends a node-assigned id packet (Assign Node ID packet, ANP) to50 The Journal of China Universities of Posts and Telecommunications 2011parent node, the format of ANP packet is shown in Table 6. Before the ANP packet arrive the node of sending GNP, all the relay nodes would establish a route to the new joining node, and add the new joining node ID as the temporarily-stored node’s child node, in order to establish the new corresponding tree topology. When the ANP packet arrive at the node of sending GNP packet (destination node) at last, the destination node will establish a route to the new joining node, then send the node ID to the child node through SNP packet. At this point, the new joining node has obtained its node ID. The format of SNP packet is shown in Table 7.Table 2 Format of SQPType Mac address of source node Data service type NodeFilter Response type Checksum 01⩒broadcast⩓Table 3 Format of RSQPType ⩒1⩓Mac address of source node Mac address of destination Value of link quality checksumTable 4 Format of JNP1Type⩒2⩓Mac address of source node Mac address of destination ChecksumTable 5 Format of GNPType⩒3⩓Source node ID Next hop ID Destination ID metricTable 6 Format of ANPType⩒4⩓Source of node id Next hop ID Destination ID Metric The new ID assigned to each levelTable 7 Format of SNPType ⩒5⩓Mac address of source node Mac address of destination Child node ID ChecksumThe new network tree topology is built through the above algorithm at last, and the new joining node obtains the relevant node ID.3 The function of self-healingBecause the channel of low voltage distribution network is time-varying, easily to break a link, an algorithm which has the function of self-healing is needed to reestablish the network topology. For example, when two nodes communicate with each other, after the sending node sends a data packet to the destination node, it will wait for a confirmation from the destination node. If the sending node receive confirmation, we are sure the link is not broken; if not receive the confirmation, then re-sent the data packet two times. However, if the sending node does not receive confirmation of the next hop node within three times, the link is considered to have been broken, and need to re-establish the route. If the broken link is shown in fig.8, the node 0X0201 will send a link break off packet (LBP) to NC node, the NC node and all the relay nodes will remove the unreachable nodes after they receive LBP packet. Then, node 0X0302 and node 0x0301 call the algorithm described in the previous section, and re-apply to join the network. The format of LBP packet is shown in Fig. 1.The other broken link situation is shown in Fig. 2. Node 0X0101 and node 0X0201 can’t communicate with each other, then node 0X0101 sends LBP packet to NC node. All the nodes have received LBP packet will remove the tree topology whose root node ID is 0X0101. Subsequently the tree topology whose root ID’s 0X0201 will re-join in the network and node 0X0201 will send a SQP packet to the up level. Because the node 0X0201 is on level 2, the Node Filter can be set to 0X01FF and response type is set to 0, which indicate only the first level can response the join request. The nodes who receive SQP packet will response RSQP packet. After the node 0X0201 receive RSQP packet, it will compare the value of link quality, and choose the node that is the source of best link as its parent node, establishing a route to NC node.The tree network topology whose root ID is 0x0201 does not need to re-apply the node ID from the NC node, and can use their original node ID, because the level where they be on have no other nodes join or leave, and if re-apply the node ID, the resulting node ID is also the same as their original ID. The node 0X0201 send a JNP2 (join notification packet) to NC node, and JNP2 packet contains the level of the sub-tree network topology and the nodes ID on this level. The format of JNP2 is shown in Fig. 11. After relay node and NC node receive the JNP2 packet, they will add the new joining node to their sub-tree network topology, and establish the route to new joining nodes, thus completing the self-healing network process.Supplement 1 LI Jie, et al. / Dynamic routing network algorithm of low voltage based on linkquality 51Fig. 1The situation of link broken 1Fig. 2 The situation of link broken 2Table 8 Format of LBPTypeSource node IDUnreachable node IDlifetime7Table 9 Format of JNP2TypeSource node IDNext hop IDDestination IDlevelNodes id of each level8NC node4 SimulationWe select the NS-2 simulation platform. The simulationobject, a physical structure, is shown in Fig. 3. Assuming that node 0 is the master plans, also called NC node, the nodes can directly communicate with it are ^`1,61,7,33,22; the nodes can directly communicate with node 61 are ^`10,20; the nodes can directly communicate with node 33 are ^`21,4,6,the nodes can directly communicate with node 7 are ^`33,21;the nodes can directly communicate with node 21 are ^`4,62;the nodes can directly communicate with node 22 are ^`32,57. The adjacent nodes can directly communicate with each other. We assume that the signal quality is inversely proportional to the distance between nodes. The simulation shows the resulting tree topology in Fig. 4.In the network topology, NC node 0 saved the entire network topology, and all the RS nodes saved the route to NC node. We can see each node is assigned the node ID and network ID from Fig. 5. Because all the nodes are in the samelogical network, they have the same network ID.Fig. 3 The physical network structureIt is assumed that the power line have more load, strong noise and channel attenuation during the evening peak, which result in number 10 node and number 20 node cannot communicate with each other, so number 20 node can’t communicate with NC node, and re-initiate the process in order to re-join the network. The number 20 node sends routing request packet by multicast, who receive the routing request packet will give the response. Suppose the relay node52 The Journal of China Universities of Posts and Telecommunications 201121 is damaged, leading the number 4 node can’t communicate with the NC node, then number 4 node re-multicast route request packet. Through the simulation in NS2 platform, the resulting network topology after self-healing is shown inFig.5.Fig. 4The resulting tree network topologyFig. 5 Tree topology after self-healing5 ConclusionsIn the limited communication capabilities circumstances of PLC, in order to improve the reliability and stability of PLC, the routing in the upper layer can improve the various properties. This paper describes the dynamic routing network algorithm based on link quality in detail. The simulation shows that the algorithm can eventually form an 8-layer structure of the tree topology, and can achieve network self-healing capabilities when the link is broken. The algorithm is suitable for a variety of network physical topology, and finally be able to form a tree structure, thus effectively improving the reliability and system flexibility of communication network.AcknowledgementsThis work was supported by the National Key project of Scientific and Technical Supporting Programs of China (2008BAH24B04, 2008BAH21B03, 2009BAH39B03); The National Natural Science Foundation of China (61072060); The Program for New Century Excellent Talents in University (NECET-08-0738); Engineering Research Center of Information Networks, Ministry of Education.References1.Xiaojun Tang. Development of ower line carrier communication during “tenone five”. Electric Power System, 2006, 27(10): 75-792.Wei Xu, Zhi Li, An adaptive routing algorithm for power linecommunication. Information and Electronic Engineering, 2010, (6): 738-741 3.Shengli Li, Shaohua Jiao, Lijun Qin. The research of power linecommunication. 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