This document presents an analysis of dimensioning multi-class IP networks to support differentiated services under over-provisioning constraints. It introduces mathematical formulations to represent the problem as mixed integer linear programs that can find optimal solutions for moderate sized networks. A heuristic approach is also proposed to solve the problem for larger networks. The formulations consider different routing schemes (per-class and per-aggregate routing) and over-provisioning constraints (per-class and per-aggregate over-provisioning). Computational results using sample networks are provided to compare the different approaches.
1) The document presents a mathematical model for optimizing the value of k in a k-fold multicast network under different traffic loads.
2) The model derives the stationary distribution of network states and develops expressions for throughput and blocking probability.
3) Results show that network throughput increases significantly as k increases up to a point, after which throughput levels off, and blocking probability levels off after a certain k value as well. An optimum k value minimizes blocking probability for a given traffic load.
Achieving Optimum Value of k in a K-fold Multicast Network with Buffer using ...cscpconf
Multicast network is widely used for effective communication, transmission and performance
optimizations of a network. In this paper, a new model has been developed to determine a
suitable value of the fold k of a k-fold multicast network under different traffic loads under
Poisson traffic with finite queue at each node. We have derived stationary distribution for the
network states and then derived expressions for the network throughput and the blocking
probability of the network. It has been found in this research work that the network throughput
increases very fast as we increase the fold number. However, at a certain value of the fold, the
blocking probability ceases to increase and it remains constant. We have also observed that as
the offered traffic is increased, the throughput also increases. Moreover, the system parameter k
is increased, the blocking probability decreases. However, after an optimum value of k, the
blocking probability remains constant for a particular value of the offered traffic. In fact, in this
paper, by evaluating the performance of a k-fold multicast network, our developed model improves the performance of a multicast network.
1) The document presents upper and lower bounds on the capacity of MIMO relay channels, which are wireless channels with multiple antennas at the source, relay, and destination nodes.
2) For fixed channel conditions, an upper bound is derived involving maximization over covariance matrices and a scalar parameter capturing signal cooperation. A lower bound is found as the maximum of the direct link and cascaded link capacities.
3) The analysis is extended to Rayleigh fading channels, where the ergodic (average) capacity is considered. It is shown that under certain conditions, the upper and lower bounds meet, characterizing the exact ergodic capacity.
OfdmaClosed-Form Rate Outage Probability for OFDMA Multi-Hop Broadband Wirele...IJASCSE
This document summarizes a research paper that analyzes the rate outage probability for OFDMA multi-hop broadband wireless networks under Nakagami-m fading channels. The paper derives closed-form expressions for the rate outage probability, moment generating function, probability distribution function, and cumulative distribution function. It considers both single-hop and multi-hop network scenarios. For single-hop networks, the paper formulates an optimization problem to maximize total transmission rate while ensuring fairness for all users.
In order enhance the network efficiency of Mobile ad hoc Networks (MANETs), an Power Unbiased Cooperative Media Access Control(PUC-MAC) protocol in MANETs was planned during this paper. It adopted the most effective partnership choice statement to select the cooperative node with higher channel condition, higher passing rate and additional balanced power consumption. Simulation results showed that PUC-MAC outperforms EC-MAC,Cooperative MAC (CoopMAC) and IEEE 802.11 Distributed Coordination perform (DCF) in terms of the packet release quantitative relation, network outturn and network lifespan beneath 2 distinct channel noise levels, particularly beneath the worst channel condition.
A comparative analysis on qos multicast routing protocols in MANETsIOSR Journals
Abstract: Simultaneous transmission of data from one sender to multiple receivers is called multicasting.
Several widely used applications require multicasting at least at the logical level. Examples include audio video
teleconferencing, real time video streaming and the maintenance of distributed databases. In many cases it is
advantageous to implement multicasting at the level of the routing algorithm (other approaches would be oneto-all
unicast or the implementation of multicasting at the application layer). In this paper we are presenting a
comparative analysis on various multicast routing protocols in adhoc networks.
Keywords: multicasting, multicast protocols,dynamic core, performance evaluation,Qos Parameters
This document summarizes a research paper that proposes CafRep, an adaptive congestion control protocol for delay-tolerant networks (DTNs). CafRep uses implicit heuristics based on contact and resource congestion to offload traffic from congested parts of the network to less congested areas. It also adaptively replicates messages at lower rates in different parts of the network with non-uniform congestion levels. The paper evaluates CafRep across three real mobility traces and shows it outperforms state-of-the-art DTN forwarding algorithms in maintaining high delivery rates while keeping low delays and packet loss, especially in congested networks.
Routing Optimization in IP/MPLS Networks under Per-Class Over-Provisioning Co...EM Legacy
This document describes research on routing optimization in IP/MPLS networks under per-class over-provisioning constraints. It introduces a heuristic approach that iteratively optimizes IGP link metrics to indirectly solve the multi-objective problem of finding routing configurations that efficiently use network resources while satisfying per-class capacity constraints and minimizing the number of explicit label switched paths (LSPs) required. The heuristic calls a traffic engineering procedure based on simulated annealing to optimize routing for aggregate demands and individual traffic classes.
1) The document presents a mathematical model for optimizing the value of k in a k-fold multicast network under different traffic loads.
2) The model derives the stationary distribution of network states and develops expressions for throughput and blocking probability.
3) Results show that network throughput increases significantly as k increases up to a point, after which throughput levels off, and blocking probability levels off after a certain k value as well. An optimum k value minimizes blocking probability for a given traffic load.
Achieving Optimum Value of k in a K-fold Multicast Network with Buffer using ...cscpconf
Multicast network is widely used for effective communication, transmission and performance
optimizations of a network. In this paper, a new model has been developed to determine a
suitable value of the fold k of a k-fold multicast network under different traffic loads under
Poisson traffic with finite queue at each node. We have derived stationary distribution for the
network states and then derived expressions for the network throughput and the blocking
probability of the network. It has been found in this research work that the network throughput
increases very fast as we increase the fold number. However, at a certain value of the fold, the
blocking probability ceases to increase and it remains constant. We have also observed that as
the offered traffic is increased, the throughput also increases. Moreover, the system parameter k
is increased, the blocking probability decreases. However, after an optimum value of k, the
blocking probability remains constant for a particular value of the offered traffic. In fact, in this
paper, by evaluating the performance of a k-fold multicast network, our developed model improves the performance of a multicast network.
1) The document presents upper and lower bounds on the capacity of MIMO relay channels, which are wireless channels with multiple antennas at the source, relay, and destination nodes.
2) For fixed channel conditions, an upper bound is derived involving maximization over covariance matrices and a scalar parameter capturing signal cooperation. A lower bound is found as the maximum of the direct link and cascaded link capacities.
3) The analysis is extended to Rayleigh fading channels, where the ergodic (average) capacity is considered. It is shown that under certain conditions, the upper and lower bounds meet, characterizing the exact ergodic capacity.
OfdmaClosed-Form Rate Outage Probability for OFDMA Multi-Hop Broadband Wirele...IJASCSE
This document summarizes a research paper that analyzes the rate outage probability for OFDMA multi-hop broadband wireless networks under Nakagami-m fading channels. The paper derives closed-form expressions for the rate outage probability, moment generating function, probability distribution function, and cumulative distribution function. It considers both single-hop and multi-hop network scenarios. For single-hop networks, the paper formulates an optimization problem to maximize total transmission rate while ensuring fairness for all users.
In order enhance the network efficiency of Mobile ad hoc Networks (MANETs), an Power Unbiased Cooperative Media Access Control(PUC-MAC) protocol in MANETs was planned during this paper. It adopted the most effective partnership choice statement to select the cooperative node with higher channel condition, higher passing rate and additional balanced power consumption. Simulation results showed that PUC-MAC outperforms EC-MAC,Cooperative MAC (CoopMAC) and IEEE 802.11 Distributed Coordination perform (DCF) in terms of the packet release quantitative relation, network outturn and network lifespan beneath 2 distinct channel noise levels, particularly beneath the worst channel condition.
A comparative analysis on qos multicast routing protocols in MANETsIOSR Journals
Abstract: Simultaneous transmission of data from one sender to multiple receivers is called multicasting.
Several widely used applications require multicasting at least at the logical level. Examples include audio video
teleconferencing, real time video streaming and the maintenance of distributed databases. In many cases it is
advantageous to implement multicasting at the level of the routing algorithm (other approaches would be oneto-all
unicast or the implementation of multicasting at the application layer). In this paper we are presenting a
comparative analysis on various multicast routing protocols in adhoc networks.
Keywords: multicasting, multicast protocols,dynamic core, performance evaluation,Qos Parameters
This document summarizes a research paper that proposes CafRep, an adaptive congestion control protocol for delay-tolerant networks (DTNs). CafRep uses implicit heuristics based on contact and resource congestion to offload traffic from congested parts of the network to less congested areas. It also adaptively replicates messages at lower rates in different parts of the network with non-uniform congestion levels. The paper evaluates CafRep across three real mobility traces and shows it outperforms state-of-the-art DTN forwarding algorithms in maintaining high delivery rates while keeping low delays and packet loss, especially in congested networks.
Routing Optimization in IP/MPLS Networks under Per-Class Over-Provisioning Co...EM Legacy
This document describes research on routing optimization in IP/MPLS networks under per-class over-provisioning constraints. It introduces a heuristic approach that iteratively optimizes IGP link metrics to indirectly solve the multi-objective problem of finding routing configurations that efficiently use network resources while satisfying per-class capacity constraints and minimizing the number of explicit label switched paths (LSPs) required. The heuristic calls a traffic engineering procedure based on simulated annealing to optimize routing for aggregate demands and individual traffic classes.
Determining the Optimum Number of Paths for Realization of Multi-path Routing...TELKOMNIKA JOURNAL
This document proposes an algorithm for determining the optimal number of paths for multi-path routing in MPLS-TE networks. The algorithm involves:
1. Constructing a network graph and finding the set of shortest paths between nodes using Dijkstra's algorithm.
2. Determining the maximum flow that can be transmitted over each shortest path based on the minimum cut using the Ford-Fulkerson theorem.
3. Considering delay as another criterion and formulating the problem as a multi-criteria optimization to maximize flow while minimizing delay.
4. Defining a utility function to reduce the problem to a single-criterion by representing the quality of criteria on a 0 to 1 scale.
5.
An artificial immune system algorithm for solving the uncapacitated single all...IJECEIAES
The present paper deals with a variant of hub location problems (HLP): the uncapac- itated single allocation p-Hub median problem (USApHMP). This problem consists to jointly locate hub facilities and to allocate demand nodes to these selected facilities. The objective function is to minimize the routing of demands between any origin and destination pair of nodes. This problem is known to be NP-hard. Based on the artificial immune systems (AIS) framework, this paper develops a new approach to efficiently solve the USApHMP. The proposed approach is in the form of a clonal selection algorithm (CSA) that uses appropriate encoding schemes of solutions and maintains their feasibility. Comprehensive experiments and comparison of the proposed approach with other existing heuristics are conducted on benchmark from civil aeronautics board, Australian post, PlanetLab and Urand data sets. The results obtained allow to demonstrate the validity and the effectiveness of our approach. In terms of solution quality, the results obtained outperform the best-known solutions in the literature.
This document describes a method for maximizing the total throughput of a two-way relay network using orthogonal frequency-division multiplexing (OFDM). The method jointly optimizes subcarrier pairing and relay selection by formulating the problem as a maximum weighted bipartite matching problem, which can be solved in polynomial time. Simulation results show that the proposed method increases total throughput compared to benchmark methods, especially as the number of relays increases. The throughput is evaluated for different numbers of subcarriers and relays to analyze the system's performance under various conditions.
The document proposes a hybrid network-on-chip (NoC) architecture that combines spatial division multiplexing (SDM)-based circuit switching and packet switching. The SDM-based circuit-switched sub-network handles streaming traffic, using SDM to increase path diversity and improve throughput. The packet-switched sub-network handles best-effort traffic and configures the circuit-switched sub-network. The hybrid router architecture was implemented in FPGA and ASIC, showing it can build a practical hybrid NoC while providing quality of service for streaming traffic without complex resource sharing.
New strategy to optimize the performance of spray and wait routing protocolijwmn
Delay Tolerant Networks have been (DTN) have been developed to support the irregular connectivity often
separate networks. The main routing problem in this type of network is embarrassed by time that is
extremely long, since connections are intermittent and opportunistic. Routing protocols must take into
account the maximum constraint encountered in this type of environment , use effective strategies
regarding the choice of relay nodes and buffer management nodes to improve the delivery of messages and
the time of their delivery . This article proposes a new strategy that optimizes the routing Spray and wait.
The proposed method uses the information contained in the messages delivered mostly paths traversed by
the messages before arriving at their destination and the time when nodes have receive these messages.
Simulation results show that the proposed strategy can increase the probability of delivery and minimizing
overhead unlike FIFO technology used with the default routing ' sprat and wait'
PERFORMANCE IMPROVEMENT OF NONREGENERATIVE COOPERATIVE RELAY NETWORKS WITH OP...ijwmn
This paper analyzes the performance of cooperative amplify-and-forward (CAF) relay networks that employ both optimal power allocation among nodes based on relay position and adaptive M-QAM/M-PSK modulation in generalized fading environments. The paper develops a unified analytical framework using marginal moment generating functions to derive expressions for average bit error rate, mean achievable spectral efficiency, and outage probability over a range of fading distributions. It applies this framework to analyze CAF relay networks with adaptive modulation over Rice fading channels. The paper also employs an approximate moment generating function to further simplify computation complexity. Finally, it applies the framework to analyze the impact of optimal power allocation based on relay position.
The document describes an improved interconnection network called Hybrid-2 for a Coarse Grain Reconfigurable Architecture called Dynamically Reprogrammable Resource Array (DRRA). Hybrid-2 allows for partial and dynamic runtime reconfiguration with fewer configuration bits than previous networks like Hybrid-1, multiplexers, networks-on-chip, and crossbars. Evaluation shows Hybrid-2 requires less area and configuration bits while providing faster configuration times compared to previous approaches.
This document summarizes research on distributed path computation algorithms that aim to prevent routing loops. It introduces the Distributed Path Computation with Intermediate Variables (DIV) algorithm, which can operate with any routing algorithm to guarantee loop-freedom. DIV generalizes previous loop-free algorithms and provably outperforms them by reducing synchronous updates and helping maintain paths during network changes. The document also reviews link-state routing, distance-vector routing, and existing loop-prevention techniques like the Diffusing Update Algorithm and Loop Free Invariance algorithms.
Vesyla is a high-level synthesis framework that maps DSP algorithms onto a coarse-grain reconfigurable architecture. It takes untimed C code as input and uses pragmas to guide the mapping and generation of configuration files for the architecture. The pragmas identify parallelism and allocate and bind operations and operands to resources. This allows the user to explore different architectural implementations from serial to fully parallel. Vesyla analyzes dependencies, schedules operations, and synchronizes parallel threads to generate the configuration files.
Towards Seamless TCP Congestion Avoidance in Multiprotocol EnvironmentsIDES Editor
In this paper we explore the area of congestion
avoidance in computer networks. We provide a brief overview
of the current state of the art in congestion avoidance and also
list our extension to the TCP congestion avoidance mechanism.
This extension was previously published on an international
forum and in this paper we describe an improved version which
allows multiprotocol support. We list preliminary results
carried out in a simulation environment.
New introduced approach called Advanced Notification
Congestion System (ACNS) allows TCP flows prioritization
based on the TCP flow age and priority carried in the header
of the network layer protocol. The aim of this approach is to
provide more bandwidth for young and high prioritized TCP
flows by means of penalizing old greedy flows with a low
priority. Using ACNS, substantial network performance
increase can be achieved.
Optimizing Data Plane Resources for Multipath FlowsIRJET Journal
This document discusses optimizing data plane resources for multipath flows. It introduces the concepts of routing with minimum overhead (RMO) and decomposition with minimum overhead (DMO) to minimize forwarding costs when splitting traffic flows across multiple paths.
The key ideas are:
1) Dividing a traffic flow across multiple paths improves bandwidth utilization but incurs higher forwarding costs due to additional network resources used.
2) RMO and DMO problems are defined to minimize these forwarding costs by reducing the number of paths or nodes used. Efficient algorithms are presented to solve the problems.
3) Simulation results show that algorithms which prefer smaller paths generally perform better at reducing the number of nodes traveled, though they may increase
Impact of mobility models on supp tran optimized dtn spray and wait routing p...ijmnct
The delay-tolerant networks (DTN) are networks that support communication between nodes when
connectivity is intermittent, due to the difficulties encountered in this type of environment, such as node
mobility frequently changing network topology, this which does not allow to route messages directly
between the source and destination, the routing algorithms must consider mobility to increase the rate of
message delivery. In our previous work of Supp-Tran we examine that spray and wait router was not
showing good delivery probability in case of SPMBM mobility model and FIFO forwarding strategy
compared to our Supp-Tran strategy.
This paper compares the behavior of the FIFO strategy used by default with spray and wait routing
protocol and that of our Supp-Tran strategy under different type of mobility, to do that the most mobility
models used are chosen to show how mobility model affects the forwarding strategy using as performance
metric such as delivery probability, the number of dropped messages , buffer time average, the overhead
ratio and average number of hops.
An Offline Hybrid IGP/MPLS Traffic Engineering Approach under LSP ConstraintsEM Legacy
This document proposes a novel hybrid IGP/MPLS traffic engineering method based on genetic algorithms to handle long or medium-term traffic variations. The method treats the maximum number of hops an LSP may take and the number of LSPs applied solely to improve routing as constraints. Results comparing this hybrid approach to pure IGP routing and full mesh MPLS with and without flow splitting on the German scientific network and other networks are presented.
Performance of cluster-based cognitive multihop networks under joint impact o...TELKOMNIKA JOURNAL
In this paper, we evaluate outage probability (OP) of a cluster-based multi-hop protocol operating
on an underlay cognitive radio (CR) mode. The primary network consists of multiple independent
transmit/receive pairs, and the primary transmitters seriously cause co-channel interference (CCI) to the
secondary receivers. To improve the outage performance for the secondary network under the joint impact
of the CCI and hardware imperfection, we employ the best relay selection at each hop. Moreover, the
destination is equipped with multiple antennas and uses the selection combining (SC) technique to
enhance the reliability of the data transmission at the last hop. For performance evaluation, we first derive
an exact formula of OP for the primary network which is used to calculate the transmit power of the
secondary transmitters. Next, an exact closed-form expression of the end-to-end OP for the secondary
network is derived over Rayleigh fading channels. We then perform Monte-Carlo simulations to validate
the derivations. The results present that the CCI caused by the primary operations significantly impacts on
the outage performance of the secondary network.
Performance comparison of mobile ad hoc network routing protocolsIJCNCJournal
Mobile Ad-hoc Network (MANET) is an infrastructure less and decentralized network which need a robust
dynamic routing protocol. Many routing protocols for such networks have been proposed so far to find
optimized routes from source to the destination and prominent among them are Dynamic Source Routing
(DSR), Ad-hoc On Demand Distance Vector (AODV), and Destination-Sequenced Distance Vector (DSDV)
routing protocols. The performance comparison of these protocols should be considered as the primary
step towards the invention of a new routing protocol. This paper presents a performance comparison of
proactive and reactive routing protocols DSDV, AODV and DSR based on QoS metrics (packet delivery
ratio, average end-to-end delay, throughput, jitter), normalized routing overhead and normalized MAC
overhead by using the NS-2 simulator. The performance comparison is conducted by varying mobility
speed, number of nodes and data rate. The comparison results show that AODV performs optimally well
not the best among all the studied protocols.
Optimizing IP Networks for Uncertain Demands Using Outbound Traffic ConstraintsEM Legacy
This document discusses various models for optimizing IP networks with uncertain demands using outbound traffic constraints. It introduces several models of increasing complexity: Model A1 specifies maximum outbound traffic per node; Model A2 adds maximum flow constraints; Model A3 groups traffic into destinations; and Model A4 combines grouping with per-group maximum flows. The models are evaluated on a sample network, showing that additional constraints can significantly reduce maximum link utilization at the cost of supporting fewer traffic variations. Overall, the models provide simple ways to characterize traffic uncertainty that can be used with heuristic optimization approaches.
Optimizing IP Networks for Uncertain Demands Using Outbound Traffic ConstraintsEM Legacy
This document summarizes an approach for optimizing routing in IP networks with uncertain traffic demands. The approach uses simple outbound traffic constraints at each node to bound the maximum traffic originating from that node. It formulates the traffic engineering problem to find optimal link weights that minimize maximum link utilization under these demand uncertainties. Computational results on a sample network show the impact of the proposed uncertainty models on performance measures like link utilization.
An Alternative Genetic Algorithm to Optimize OSPF WeightsEM Legacy
This document presents a genetic algorithm approach to optimize OSPF routing weights. The algorithm aims to minimize maximum and average link utilization directly, unlike previous methods that minimized a convex cost function. It can find weights for both single and multiple shortest path routing. The genetic algorithm uses a chromosome encoding of link weights. It selects parents using rank selection and produces offspring using a reproduction strategy combining crossover and mutation. Additional mutation is applied to offspring not meeting certain conditions. The algorithm is tested on small networks and compared to MIP-based methods, showing results for larger networks with increasing traffic demands.
Determining the Optimum Number of Paths for Realization of Multi-path Routing...TELKOMNIKA JOURNAL
This document proposes an algorithm for determining the optimal number of paths for multi-path routing in MPLS-TE networks. The algorithm involves:
1. Constructing a network graph and finding the set of shortest paths between nodes using Dijkstra's algorithm.
2. Determining the maximum flow that can be transmitted over each shortest path based on the minimum cut using the Ford-Fulkerson theorem.
3. Considering delay as another criterion and formulating the problem as a multi-criteria optimization to maximize flow while minimizing delay.
4. Defining a utility function to reduce the problem to a single-criterion by representing the quality of criteria on a 0 to 1 scale.
5.
An artificial immune system algorithm for solving the uncapacitated single all...IJECEIAES
The present paper deals with a variant of hub location problems (HLP): the uncapac- itated single allocation p-Hub median problem (USApHMP). This problem consists to jointly locate hub facilities and to allocate demand nodes to these selected facilities. The objective function is to minimize the routing of demands between any origin and destination pair of nodes. This problem is known to be NP-hard. Based on the artificial immune systems (AIS) framework, this paper develops a new approach to efficiently solve the USApHMP. The proposed approach is in the form of a clonal selection algorithm (CSA) that uses appropriate encoding schemes of solutions and maintains their feasibility. Comprehensive experiments and comparison of the proposed approach with other existing heuristics are conducted on benchmark from civil aeronautics board, Australian post, PlanetLab and Urand data sets. The results obtained allow to demonstrate the validity and the effectiveness of our approach. In terms of solution quality, the results obtained outperform the best-known solutions in the literature.
This document describes a method for maximizing the total throughput of a two-way relay network using orthogonal frequency-division multiplexing (OFDM). The method jointly optimizes subcarrier pairing and relay selection by formulating the problem as a maximum weighted bipartite matching problem, which can be solved in polynomial time. Simulation results show that the proposed method increases total throughput compared to benchmark methods, especially as the number of relays increases. The throughput is evaluated for different numbers of subcarriers and relays to analyze the system's performance under various conditions.
The document proposes a hybrid network-on-chip (NoC) architecture that combines spatial division multiplexing (SDM)-based circuit switching and packet switching. The SDM-based circuit-switched sub-network handles streaming traffic, using SDM to increase path diversity and improve throughput. The packet-switched sub-network handles best-effort traffic and configures the circuit-switched sub-network. The hybrid router architecture was implemented in FPGA and ASIC, showing it can build a practical hybrid NoC while providing quality of service for streaming traffic without complex resource sharing.
New strategy to optimize the performance of spray and wait routing protocolijwmn
Delay Tolerant Networks have been (DTN) have been developed to support the irregular connectivity often
separate networks. The main routing problem in this type of network is embarrassed by time that is
extremely long, since connections are intermittent and opportunistic. Routing protocols must take into
account the maximum constraint encountered in this type of environment , use effective strategies
regarding the choice of relay nodes and buffer management nodes to improve the delivery of messages and
the time of their delivery . This article proposes a new strategy that optimizes the routing Spray and wait.
The proposed method uses the information contained in the messages delivered mostly paths traversed by
the messages before arriving at their destination and the time when nodes have receive these messages.
Simulation results show that the proposed strategy can increase the probability of delivery and minimizing
overhead unlike FIFO technology used with the default routing ' sprat and wait'
PERFORMANCE IMPROVEMENT OF NONREGENERATIVE COOPERATIVE RELAY NETWORKS WITH OP...ijwmn
This paper analyzes the performance of cooperative amplify-and-forward (CAF) relay networks that employ both optimal power allocation among nodes based on relay position and adaptive M-QAM/M-PSK modulation in generalized fading environments. The paper develops a unified analytical framework using marginal moment generating functions to derive expressions for average bit error rate, mean achievable spectral efficiency, and outage probability over a range of fading distributions. It applies this framework to analyze CAF relay networks with adaptive modulation over Rice fading channels. The paper also employs an approximate moment generating function to further simplify computation complexity. Finally, it applies the framework to analyze the impact of optimal power allocation based on relay position.
The document describes an improved interconnection network called Hybrid-2 for a Coarse Grain Reconfigurable Architecture called Dynamically Reprogrammable Resource Array (DRRA). Hybrid-2 allows for partial and dynamic runtime reconfiguration with fewer configuration bits than previous networks like Hybrid-1, multiplexers, networks-on-chip, and crossbars. Evaluation shows Hybrid-2 requires less area and configuration bits while providing faster configuration times compared to previous approaches.
This document summarizes research on distributed path computation algorithms that aim to prevent routing loops. It introduces the Distributed Path Computation with Intermediate Variables (DIV) algorithm, which can operate with any routing algorithm to guarantee loop-freedom. DIV generalizes previous loop-free algorithms and provably outperforms them by reducing synchronous updates and helping maintain paths during network changes. The document also reviews link-state routing, distance-vector routing, and existing loop-prevention techniques like the Diffusing Update Algorithm and Loop Free Invariance algorithms.
Vesyla is a high-level synthesis framework that maps DSP algorithms onto a coarse-grain reconfigurable architecture. It takes untimed C code as input and uses pragmas to guide the mapping and generation of configuration files for the architecture. The pragmas identify parallelism and allocate and bind operations and operands to resources. This allows the user to explore different architectural implementations from serial to fully parallel. Vesyla analyzes dependencies, schedules operations, and synchronizes parallel threads to generate the configuration files.
Towards Seamless TCP Congestion Avoidance in Multiprotocol EnvironmentsIDES Editor
In this paper we explore the area of congestion
avoidance in computer networks. We provide a brief overview
of the current state of the art in congestion avoidance and also
list our extension to the TCP congestion avoidance mechanism.
This extension was previously published on an international
forum and in this paper we describe an improved version which
allows multiprotocol support. We list preliminary results
carried out in a simulation environment.
New introduced approach called Advanced Notification
Congestion System (ACNS) allows TCP flows prioritization
based on the TCP flow age and priority carried in the header
of the network layer protocol. The aim of this approach is to
provide more bandwidth for young and high prioritized TCP
flows by means of penalizing old greedy flows with a low
priority. Using ACNS, substantial network performance
increase can be achieved.
Optimizing Data Plane Resources for Multipath FlowsIRJET Journal
This document discusses optimizing data plane resources for multipath flows. It introduces the concepts of routing with minimum overhead (RMO) and decomposition with minimum overhead (DMO) to minimize forwarding costs when splitting traffic flows across multiple paths.
The key ideas are:
1) Dividing a traffic flow across multiple paths improves bandwidth utilization but incurs higher forwarding costs due to additional network resources used.
2) RMO and DMO problems are defined to minimize these forwarding costs by reducing the number of paths or nodes used. Efficient algorithms are presented to solve the problems.
3) Simulation results show that algorithms which prefer smaller paths generally perform better at reducing the number of nodes traveled, though they may increase
Impact of mobility models on supp tran optimized dtn spray and wait routing p...ijmnct
The delay-tolerant networks (DTN) are networks that support communication between nodes when
connectivity is intermittent, due to the difficulties encountered in this type of environment, such as node
mobility frequently changing network topology, this which does not allow to route messages directly
between the source and destination, the routing algorithms must consider mobility to increase the rate of
message delivery. In our previous work of Supp-Tran we examine that spray and wait router was not
showing good delivery probability in case of SPMBM mobility model and FIFO forwarding strategy
compared to our Supp-Tran strategy.
This paper compares the behavior of the FIFO strategy used by default with spray and wait routing
protocol and that of our Supp-Tran strategy under different type of mobility, to do that the most mobility
models used are chosen to show how mobility model affects the forwarding strategy using as performance
metric such as delivery probability, the number of dropped messages , buffer time average, the overhead
ratio and average number of hops.
An Offline Hybrid IGP/MPLS Traffic Engineering Approach under LSP ConstraintsEM Legacy
This document proposes a novel hybrid IGP/MPLS traffic engineering method based on genetic algorithms to handle long or medium-term traffic variations. The method treats the maximum number of hops an LSP may take and the number of LSPs applied solely to improve routing as constraints. Results comparing this hybrid approach to pure IGP routing and full mesh MPLS with and without flow splitting on the German scientific network and other networks are presented.
Performance of cluster-based cognitive multihop networks under joint impact o...TELKOMNIKA JOURNAL
In this paper, we evaluate outage probability (OP) of a cluster-based multi-hop protocol operating
on an underlay cognitive radio (CR) mode. The primary network consists of multiple independent
transmit/receive pairs, and the primary transmitters seriously cause co-channel interference (CCI) to the
secondary receivers. To improve the outage performance for the secondary network under the joint impact
of the CCI and hardware imperfection, we employ the best relay selection at each hop. Moreover, the
destination is equipped with multiple antennas and uses the selection combining (SC) technique to
enhance the reliability of the data transmission at the last hop. For performance evaluation, we first derive
an exact formula of OP for the primary network which is used to calculate the transmit power of the
secondary transmitters. Next, an exact closed-form expression of the end-to-end OP for the secondary
network is derived over Rayleigh fading channels. We then perform Monte-Carlo simulations to validate
the derivations. The results present that the CCI caused by the primary operations significantly impacts on
the outage performance of the secondary network.
Performance comparison of mobile ad hoc network routing protocolsIJCNCJournal
Mobile Ad-hoc Network (MANET) is an infrastructure less and decentralized network which need a robust
dynamic routing protocol. Many routing protocols for such networks have been proposed so far to find
optimized routes from source to the destination and prominent among them are Dynamic Source Routing
(DSR), Ad-hoc On Demand Distance Vector (AODV), and Destination-Sequenced Distance Vector (DSDV)
routing protocols. The performance comparison of these protocols should be considered as the primary
step towards the invention of a new routing protocol. This paper presents a performance comparison of
proactive and reactive routing protocols DSDV, AODV and DSR based on QoS metrics (packet delivery
ratio, average end-to-end delay, throughput, jitter), normalized routing overhead and normalized MAC
overhead by using the NS-2 simulator. The performance comparison is conducted by varying mobility
speed, number of nodes and data rate. The comparison results show that AODV performs optimally well
not the best among all the studied protocols.
Optimizing IP Networks for Uncertain Demands Using Outbound Traffic ConstraintsEM Legacy
This document discusses various models for optimizing IP networks with uncertain demands using outbound traffic constraints. It introduces several models of increasing complexity: Model A1 specifies maximum outbound traffic per node; Model A2 adds maximum flow constraints; Model A3 groups traffic into destinations; and Model A4 combines grouping with per-group maximum flows. The models are evaluated on a sample network, showing that additional constraints can significantly reduce maximum link utilization at the cost of supporting fewer traffic variations. Overall, the models provide simple ways to characterize traffic uncertainty that can be used with heuristic optimization approaches.
Optimizing IP Networks for Uncertain Demands Using Outbound Traffic ConstraintsEM Legacy
This document summarizes an approach for optimizing routing in IP networks with uncertain traffic demands. The approach uses simple outbound traffic constraints at each node to bound the maximum traffic originating from that node. It formulates the traffic engineering problem to find optimal link weights that minimize maximum link utilization under these demand uncertainties. Computational results on a sample network show the impact of the proposed uncertainty models on performance measures like link utilization.
An Alternative Genetic Algorithm to Optimize OSPF WeightsEM Legacy
This document presents a genetic algorithm approach to optimize OSPF routing weights. The algorithm aims to minimize maximum and average link utilization directly, unlike previous methods that minimized a convex cost function. It can find weights for both single and multiple shortest path routing. The genetic algorithm uses a chromosome encoding of link weights. It selects parents using rank selection and produces offspring using a reproduction strategy combining crossover and mutation. Additional mutation is applied to offspring not meeting certain conditions. The algorithm is tested on small networks and compared to MIP-based methods, showing results for larger networks with increasing traffic demands.
Internet Traffic Engineering for Partially Uncertain DemandsEM Legacy
This document summarizes an academic paper about modeling and solving the problem of routing network traffic with both fixed and uncertain demands. It considers routing strategies that use link metrics to determine shortest paths in IP networks. The proposed model represents uncertain demands using a hose model that specifies maximum aggregate traffic amounts. It calculates link loads by combining loads from fixed demands, maximum outbound uncertain demands, and maximum inbound uncertain demands. Computational results are presented for both multiple and unique shortest path routing strategies to demonstrate the benefits of considering both fixed and uncertain traffic demands.
OPTIMIZATION OF IP NETWORKS IN VARIOUS HYBRID IGP/MPLS ROUTING SCHEMESEM Legacy
The document discusses optimization of traffic engineering in hybrid IGP/MPLS networks using a genetic algorithm approach. It formulates the problem and introduces notation for the network topology, link capacities, traffic demands, and label switched paths (LSPs). It then describes three hybrid routing schemes - basic IGP shortcut, IGP shortcut, and overlay - that combine IGP routing with MPLS. The document proposes using a genetic algorithm to solve the optimization problem. It describes encoding potential solutions as chromosomes, where each value represents an LSP assignment for a traffic flow. The algorithm aims to minimize network congestion by evolving populations of chromosomes over iterations to find optimal LSP configurations. Results are presented for the German scientific network topology.
An Alternative Genetic Algorithm to Optimize OSPF WeightsEM Legacy
This document proposes an alternative genetic algorithm to optimize OSPF weights. It summarizes (1) how OSPF routing currently uses static weights that do not adapt to traffic, which can lead to unbalanced loads, (2) the genetic algorithm's objective of finding weight sets that minimize maximum and average link utilization given traffic demands, and (3) results showing the genetic algorithm finds solutions matching optimal solutions from 95-32% of the time on test networks.
Efficient Planning and Offline Routing Approaches for IP NetworksEM Legacy
Pre-print archive of my dissertation on Efficient Planning and Offline Routing Approaches for IP Networks, Departement of Communication Networks, Technische Universitaet Hamburg-Harburg 2006
IMPACT OF PARTIAL DEMAND INCREASE ON THE PERFORMANCE OF IP NETWORKS AND RE-OP...EM Legacy
12th GI/ITG CONFERENCE ON MEASURING, MODELLING AND EVALUATION OF COMPUTER AND COMMUNICATION SYSTEMS 3rd POLISH-GERMAN TELETRAFFIC SYMPOSIUM
PGTS 2004
Eueung Mulyana, Ulrich Killat
Optimization of IP Networks in Various Hybrid IGP/MPLS Routing SchemesEM Legacy
This document discusses optimization of IP networks using hybrid IGP/MPLS routing schemes. It proposes a heuristic approach using genetic algorithms to optimize network performance metrics like utilization and hop count while minimizing the number of label switched paths (LSPs). The document presents models for different hybrid routing approaches, a problem formulation, and results from applying the genetic algorithm approach to a case study network.
Efficient Planning and Offline Routing Approaches for IP NetworksEM Legacy
This document discusses routing and traffic engineering approaches for IP networks. It covers several topics: metric-based traffic engineering in classical IP networks using hybrid genetic algorithms; routing and re-optimization under partial demand increases; routing and dimensioning in multi-class IP/MPLS networks with per-class over-provisioning; and heuristic approaches for backup capacity provisioning under demand uncertainty. The document outlines computational studies demonstrating the effectiveness of the proposed approaches.
This document provides an introduction to linear programming solvers such as lp_solve, GLPK, AMPL/CPLEX, and online LP solvers. It discusses how to formulate linear programs and integer programs. Examples are provided to demonstrate how to write formulations in the input formats of different solvers and solve problems using lp_solve, GLPK, and AMPL/CPLEX. Various solvers and their capabilities are also briefly described.
This document describes a multi-path routing algorithm for IP networks based on flow optimization. It presents an intra-domain routing algorithm that uses multi-commodity flow optimization to enable load-sensitive forwarding over multiple paths without being constrained by traditional routing protocols like OSPF. The key idea is to aggregate all traffic destined for the same egress node into one commodity during optimization, reducing the number of commodities significantly. This makes the computation tractable and allows forwarding based on destination addresses.
The 3GPP Long Term Evolution Advanced (LTE-A) standard specifies a set of pioneer features such as relay nodes and carrier aggregation. At the same time, the Software Defined Networks (SDN) have become an emerging technology which provides centralized control and programmability to modern networks. In the current communication environment, cloud computing could combine the advantages of both technologies in order to create a novel cloud assisted Software Defined LTEA architecture with relay nodes. Moreover, due to the increased requirements of modern services, the optimal resource allocation is a necessity. In such a context, this paper describes a QoS aware cross carrier scheduler for downlink flows, aiming at the optimization of system resources allocation. The proposed scheduler is evaluated against the PF, MLWDF, EXP/PF, EXP RULE, LOG RULE, FLS and FLSA schedulers in a cloud assisted Software Defined LTE-A topology with relay nodes. Simulation results show that the proposed scheduler improves the real time services performance while at the same time maintains an acceptable performance for best effort flows.
MuMHR: Multi-path, Multi-hop Hierarchical RoutingM H
This document proposes a new routing protocol called MuMHR for wireless sensor networks. MuMHR aims to improve energy efficiency and robustness over LEACH in three ways: 1) By enabling nodes to select cluster heads based on the number of hops away to reduce transmission distances. 2) By using a back-off timer and multiple paths for transmissions to reduce setup overhead and add reliability. 3) By electing backup cluster heads to substitute when primary heads fail. The protocol operates in setup and data transfer phases, with the setup phase selecting cluster heads and forming clusters in an energy-efficient multi-hop manner.
Computer network is becoming more popular and common, the need to use the broadband connection services (e-learning - online training, video conferencing - online conference, IPTV - digital TV ...) of organizations and individuals is increasing. Multicast is an effective mechanism for the transmission of information and data to many recipients simultaneously. Multicast is a routing problem from a source node to a receiver node set, also known as the routing from one point to multipoint. The advances in technology and multimedia applications emerge quickly has provided great motivation for the application of new real-time multi-point. Many multi-point applications will not function properly if the QoS (quality of service) can not be guaranteed. Therefore, multi-point algorithms must be able to meet the QoS constraints (cost, reliability, bandwidth, jitter, delay...). The objective of multicast routing algorithms guarantee QoS is to provide routing algorithms have the ability to recognize the tree to satisfy the maximum of traffic streams with QoS requirements. Most multicast algorithms on MPLS (MultiProtocol Label Switching) considered the unique QoS constraint as bandwidth. The other QoS constraints can be converted into bandwidth efficiency. Starting from this reality, this paper research multicast routing algorithms guarantee bandwidth and propose new algorithm compares with existing ones.
CPCRT: Crosslayered and Power Conserved Routing Topology for congestion Cont...IOSR Journals
The document describes a proposed Crosslayered and Power Conserved Routing Topology (CPCRT) for congestion control in mobile ad hoc networks. The CPCRT aims to improve transmission performance by distinguishing between packet loss due to link failure versus other causes, while also conserving power used for packet transmission. It builds upon an earlier Crosslayered Routing Topology (CRT) approach by incorporating power conservation. The CPCRT is intended to identify the root cause of packet loss, avoid unnecessary congestion handling from link failures, allow congestion handling at specific high-traffic nodes rather than all nodes, and optimize resource and power usage for packet routing in mobile ad hoc networks.
Performance evaluation of MANET routing protocols based on QoS and energy p...IJECEIAES
Routing selection and supporting Quality of Service (QoS) are fundamental problems in Mobile Ad Hoc Network (MANET). Many different protocols have been proposed in the literature and some performance simulations are made to address this challenging task. This paper discusses the performance evaluation and comparison of two typical routing protocols; Ad Hoc On-Demand Distance Vector (AODV) and Destination-Sequenced DistanceVector (DSDV) based on measuring the power consumption in network with varing of the QoS parameters. In this paper, we have studied and analyzed the impact of variations in QoS parameter combined with the choice of routing protocol, on network performance. The network performance is measured in terms of average throughput, packet delivery ratio (PDR), average jitter and energy consumption. The simulations are carried out in NS-3. The simulation results show that DSDV and AODV routing protocols are less energy efficient. The main aim of this paper is to highlight the directions for the future design of routing protocol which would be better than the existing ones in terms of energy utilization and delivery ratio.
Multicast Routing Protocol with Group-Level Congestion Prediction and Perman...IOSR Journals
This document proposes a cross-layered model for congestion prediction and management in mobile ad hoc networks that aims to efficiently distribute network resources. The model incorporates two algorithms: Group-level Congestion Prediction (GCP) that predicts congestion levels at relay nodes with high accuracy, and Group-level Egress Permanence (GEP) that works sequentially with GCP for congestion detection and management. The document discusses related work on multicast routing protocols and energy-efficient multicasting. It then describes the proposed congestion control mechanism under constrained energy utilization and outlines the proposed model with relevant notations before focusing on the GCP and GEP algorithms.
Adaptive resource allocation and internet traffic engineering on data networkcsandit
This research paper describes the issues of bandwidth allocation, optimum capacity allocation,network operational cost reduction, and improve Internet user experience. Traffic engineering (TE) is used to manipulate network traffic to achieve certain requirements and meets certain
needs. TE becomes one of the most important building blocks in the design of the Internet backbone infrastructure. Research objective: efficient allocation of bandwidth across multiple paths. Optimum path selection. Minimize network traffic delays and maximize bandwidth utilization over multiple network paths. The bandwidth allocation is performed proportionally over multiple paths based on the path capacity.
A downlink scheduler supporting real time services in LTE cellular networksUniversity of Piraeus
The wide spread of real-time services in wireless networks demands scheduling mechanisms supporting strict Quality of Service (QoS) requirements. Nevertheless, the specifications of the LTE standard for mobile connectivity defined by the 3rd Generation Partnership Project (3GPP) does not impose any specific scheduler for the proper allocation of resources to services. Therefore, several LTE schedulers have been proposed in the literature meeting the QoS requirements of modern services. In this paper a QoS aware scheduler for the LTE downlink is proposed namely the FLS-Advanced (FLSA) aiming at prioritizing real-time traffic. The proposed scheduler has been built on three distinct levels assigning the available radio resources to services according to their requirements. Based on simulation results, the FLSA outperforms in terms of packet loss ratio, attainable throughput and fairness the performance of existing schedulers including PF, MLWDF, EXP/PF, FLS, EXP RULE and LOG RULE.
This document discusses adaptive multistreaming over a network using the Stream Control Transmission Protocol (SCTP). It proposes adapting the number of streams based on estimates of available bandwidth and current congestion window size to improve performance under congestion. The performance of this adaptive streams mechanism is evaluated through computer simulation using the OMNeT++ network simulation tool and INET framework. Simulation results are compared between the proposed adaptive streams approach and normal SCTP streaming.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
This document summarizes a study that evaluates traffic load for multiple user types in mobile WiMAX networks. It begins with background on the growth of wireless broadband and the capabilities of mobile WiMAX technology. It then describes an algorithm to calculate the maximum number of subscribers a mobile WiMAX sector can support based on system parameters and traffic models. The algorithm calculates throughput by determining overhead values and available bandwidth for downlink and uplink transmissions separately. It accounts for factors like modulation distribution, frame structure, control signaling overhead from maps and ranging, and traffic from different applications. The method is intended to help network operators estimate infrastructure needs for deploying wide-area mobile WiMAX networks.
IRJET- An Efficient Cross-Layer Cooperative Diversity Optimization Scheme Tog...IRJET Journal
The document summarizes a research paper that proposes an efficient cross-layer cooperative diversity optimization scheme called CCDRA+DEL-CMAC to maximize network lifetime and energy efficiency in mobile ad hoc networks (MANETs). The proposed scheme considers relay selection, routing, and power allocation strategies to meet reliability constraints in MANETs. Simulation results show the cross-layer cooperative strategies significantly prolong network lifetime and achieve energy savings compared to other approaches.
This document discusses challenges faced by service providers in migrating legacy transport networks to an End-to-End Integrated Optical Packet Network (E2-IOPN). It reviews technologies currently used in access, metro and core networks, including DSL, GPON, SDH, MPLS-TP and DWDM. The document then outlines issues with the transition, and proposes a strategy for service providers to implement an E2-IOPN based on SDN/NFV for improved network control and service provisioning. A cost analysis demonstrates the financial benefits of introducing new packet-based technologies.
New adaptation method based on cross layer and TCP over protocols to improve ...IJECEIAES
This document proposes a new adaptation method to improve quality of service in mobile ad hoc networks. The method uses a cross-layer approach combining modifications to the IEEE 802.11 MAC standard with a new version of TCP. It takes node mobility, signal strength, and routing protocols into account. Simulation results show the proposal achieves better TCP performance and throughput while improving energy efficiency compared to normal TCP, especially when using the OLSR routing protocol.
Fairness Comparison of TCP Variants over Proactive and Reactive Routing Proto...IJECEIAES
Mobile ad hoc networks (MANETs) are applicable in an infrastructureless environment where the mobile devices act as routers and intermediate nodes are used to transfer segments to their final destination. As Transmission control protocol (TCP) was originated for Internet with fundamentally different properties, faces serious challenges when used in mobile ad hoc networks. TCP functionality degrades, due to special properties of MANET such as route failure because of significant change of network topology and link errors. TCP uses Congestion Control Algorithms; TCP Vegas is one of them which claim to have better throughput comparing with other TCP variants in a wired network. Fairness issues of TCP Variants in MANET including existing routing protocol are still unsolved. To determine the best TCP Variants in MANET environment over renowned routing protocol is the main objective of this paper. A Study on the throughput fairness of TCP Variants namely, Vegas, Reno, New Reno, SACK, FACK, and Cubic are performed via simulation experiment using network simulator (ns-2) over existing routing protocol, named, AODV, AOMDV, DSDV, and DSR. This fairness evaluation of TCP flows arranged a contrast medium for the TCP Variants using stated routing protocol in MANET. However, TCP Vegas obtain unfair throughput in MANET. The simulation results show that TCP Reno outperforms other TCP variants under DSDV routing protocol.
The document proposes a Crosslayered and Power Conserved Routing Topology (CPCRT) for congestion control in mobile ad hoc networks. CPCRT aims to distinguish between packet loss due to link failure versus other causes like congestion. It takes a cross-layer approach using information from the physical, MAC, and application layers. The proposed method also aims to conserve power during packet transmission by adjusting transmission power levels based on received signal strength. Simulation results show that CPCRT can better utilize resources and conserve power during congestion control compared to other approaches.
Traffic engineering is one of the major issues that has to be addressed in Metro Ethernet networks for quality of service and efficient resource utilization. This paper aims at understanding the relevant issues and outlines novel algorithms for multipoint traffic engineering in Metro Ethernet. We present an algorithmic solution for traffic engineering in Metro Ethernet using optimal multiple spanning trees. This iterative approach distributes traffic across the network uniformly without overloading network resources. We also introduce a new traffic specification model for Metro Ethernet, which is a hybrid of two widely used traffic specification models, the pipe and hose models.
This document reviews Network-on-Chip (NoC) architectures that prioritize selected data streams to reduce communication latency. It categorizes the architectures based on the effect of prioritization (per end-to-end connection, per router, or per path segment) and discusses their pros and cons. Architectures that prioritize at the core-to-core level provide the highest latency reduction by bypassing the NoC, while those prioritizing per router or path segment require redetermining priority at each hop.
A Survey On Secure Cooperative Bait Detection Approach For...Jennifer Perry
This document discusses designing an MPLS VPN network for a customer with multiple locations. It covers key topics such as MPLS and VPN technologies, how MPLS VPN works, and security considerations. The design would involve configuring MPLS on routers to create tunnels between sites and establish VPNs to allow private communications over a shared infrastructure. Proper configuration is important to provide security and isolation between customer networks.
Assessing Buffering with Scheduling Schemes in a QoS Internet RouterIOSR Journals
This document examines different scheduling algorithms that could be used with RIO-C penalty enforcement buffering in a multi-queue QoS router to improve network performance. It simulates priority, round robin, and weighted round robin scheduling with RIO-C buffering. The results show that priority scheduling achieved the lowest loss rates, with 29.46% scheduler drop rate and 14.95% RED loss rate. Round robin was second with 29.53% and 10.50% losses. Weighted round robin was third with 30.28% and 3.04% losses. The document concludes that a network seeking quality of service could adopt priority scheduling with RIO-C admission control.
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Dimensioning of Multi-Class Over-Provisioned IP Networks
1. Dimensioning of Multi-Class Over-Provisioned IP Networks
Eueung Mulyana, Henning Stahlke and Ulrich Killat
Department of Communication Networks
Hamburg University of Technology (TUHH)
Address : BA IVD, Schwarzenbergstrasse 95, 21073 Hamburg
Phone: +49-40-42878-3444, Fax : +49-40-42878-2941
Email:{mulyana|henning.stahlke|killat}@tuhh.de
Abstract: The increasing traffic of data-centric applications has begun to dominate
most of today’s communication networks. Both network providers and their customers
e.g. Internet Service Providers (ISPs) are faced with the issue, how they can effectively
plan and adapt their networks and services for the future. In this paper we address the
problem of dimensioning of IP/MPLS (Multi-Protocol Label Switching) networks to
support differentiated services under per-class over-provisioning constraints with sev-
eral different routing strategies. We present several (Mixed) Integer Linear Program-
ming formulations for the problem, which can be applied to find optimal solutions for
network instances of moderate sizes. For comparison purposes as well as for solving
the problem for larger network instances a heuristic approach has been proposed. Sev-
eral computational results using two sample networks are provided.
Keywords: network dimensioning, network design, IP/MPLS, differentiated services
(DiffServ).
1. INTRODUCTION
The role of IP networks has become more and more important as the need for di-
verse communication services is growing rapidly. Both network providers (carriers)
and their customers e.g. Internet Service Providers (ISPs) are confronted with increas-
ing business competition. One of the important aspects is how they can provide better
and new inovative services and keep investment and operational costs as low as possi-
ble while maximizing revenues and guaranteeing grades of service. From ISPs’ point
of view this means that they have to provision and adapt their networks efficiently
subject to services offered to their customers. In other words, they are continuously
faced with some strategic planning problems, that have to be solved each time the
existing network infrastructure can not accommodate the new demand and service re-
quirements. In this paper we address the problem of IP/MPLS (Multi-Protocol Label
Switching) [7] network dimensioning to support differentiated services (DiffServ) [15]
under per-class over-provisioning constraints with several different routing schemes.
2. 2,(1,6) 2,(1,6)h
h1,(1,6)
2,(1,6)
4
5 6
1 1 2
1
11
0
1
1
1 2
3 4
5 6
(a) (b) (c)
1
10
0
0
0
1 2
3 4
5 6
2
20
0
0
0
1 2
3
h
h1,(1,6)h1,(1,6)
h
Figure 1. Some illustrations showing the number of transport modules to be installed
for different routing strategies and over-provisioning constraints, see text.
MPLS and DiffServ have been developed to support quality of service (QoS) in IP
networks. In contrast to classical ones, IP networks deploying MPLS and DiffServ
have two main benefits: (i) MPLS provides a basic means to better control IP traffic by
allowing explicit path routing [3,16]; and (ii) DiffServ gives the possibility to differen-
tiate treatments for IP packets with respect to their class of service. Furthermore, we
consider Over-Provisioning (OP) constraints since currently OP is a usual and prac-
tical way for ISPs to provide a certain level of QoS in their networks and it seems
that it will still be an important aspect in providing QoS for IP networks in the future.
OP basically means avoiding overload by ensuring that capacity of all links is greater
than demand both in normal or in failure situations [10]. It is also useful for dealing
with large variation in traffic demand or with delays required for link capacity upgrade
due to current technology limitations. In the context of multi-class IP networks, OP
requirements can be deployed both based on per-class or per-aggregate traffic. Here
we use the term aggregate simply to point to the total traffic regardless of its class of
service. In this paper we also focus on per-class OP constraints, since per-class OP
is the more general situation and for most cases it is economically cheaper than OP
applied to the total traffic [2]. The problem of IP network dimensioning using Diff-
Serv architecture is relatively new and therefore, to the best of our knowledge, there
are only a few publications in this area e.g. [11]. In this regard, our main contributions
are in the following aspects: (i) we use a simple and practical per-class OP mechanism
as a means for providing QoS; (ii) we present several (M)ILP ((Mixed) Integer Linear
Programming) formulations for the problem, with several different routing schemes;
and (iii) we propose a simple and flexible heuristic approach that can be extended by or
combined with metaheuristic-based optimization frameworks. Furthermore, the prob-
lem and corresponding solving approach considered in this paper can be applied to
both using the classical technology, where the necessary connections are leased from
and established by carriers, or using the future technology, where the circuits can be
established and released on demand by the ISPs. The first case is represented e.g. by
the IP over SDH (Synchronous Digital Hierarchy) architecture, where the ISPs have
3. to decide which and how many STM (Synchronous Tranport Module) lines on which
links should be installed to accomodate all demand and QoS requirements. The latter
case can be represented e.g. by the IP over OTN (Optical Transport Networks) ar-
chitecture, assuming that carriers offer a non-linear cost structure giving benefits for
establishing a larger capacity between two arbitrary nodes in their networks. The re-
mainder of this paper is organized as follows. The following section introduces some
notations and mathematically describes the problems of dimensioning of multi-class
over-provisioned IP networks. In Section 3 we discuss the heuristic which will be used
for solving the problems. Finally, in Section 4 we present some results for the case of
two sample networks.
2. PROBLEM DESCRIPTION
In contrast to the classical IP networks which perform hop-by-hop destination-based
packet forwarding, routing in IP/MPLS networks is much more flexible: packets to
a certain destination can be routed differently using different Label Switched Paths
(LSPs). The considerations that determine how a packet is assigned to a Forwarding
Equivalence Class (FEC) can become more complicated than just evaluating a destina-
tion address [7]. In the context of multi-class (DiffServ) IP networks, it is sometimes
desirable to perform class-based routing i.e. use different LSPs for different classes of
traffic, so that the physical network is divided into multiple virtual networks: one for
each traffic class [16]. In this paper, we consider two routing schemes: (i) per-class
routing scheme, where LSPs of different traffic classes for the same node pair can
follow different paths; and (ii) per-aggregate routing scheme, where each LSP has to
follow the same path without consideration of the traffic class. Moreover, we assume
that IP/MPLS routers are capable to consider multiple parallel links as a link bundle
in order to increase network efficiency [9]. Figure 1 depicts a dimensioning problem
for three different cases. This example focuses on the demand between nodes 1 and 6,
which consists of two classes. It is assumed that: (i) there is only one type of transport
modules available, which has a capacity of 100 units; (ii) for each traffic class, a given
minimum OP factor of 4 has to be achieved; and (iii) the flow h1,(1,6) of traffic class
1 and h2,(1,6) of traffic class 2 are each of 20 units capacity. An actual OP factor for
a certain traffic class on a link is calculated as the ratio of the available link capacity
to the load contributed by the corresponding traffic class. In this example, traffic class
1 is always assumed as more important than traffic class 2. Thus, for calculating the
OP factor for traffic class 2, the available capacity is the total capacity minus the load
contributed by traffic class 1. Figure 1(a) shows the case of per-class routing scheme
under per-class OP constraints. With this strategy an actual minimum OP factor of 5
for both traffic classes can be achieved by installing 6 transport modules: one transport
module for each link except for link (3, 4). Figure 1(b) shows the case of per-aggregate
routing scheme under per-class OP constraints. With this strategy an actual minimum
OP factor of 5 for traffic class 1 and 4 for traffic class 2 can be achieved by installing
3 transport modules on links (1, 2),(2, 4) and (4, 6). Finally, Figure 1(c) shows the
4. Table 1
Some notations used in the formulation
sets:indices
Θ : θ traffic classes
T : t, s types of transport modules
D : d demands (node pairs)
Pd : p candidate paths for flows realizing demand d
E : e links
constants
δedp = 1, if link e belongs to path p realizing demand d;
= 0, otherwise
hθd volume of demand d for class θ
cOP
θ given minimum OP factor for class θ
cOP
aggr given minimum OP factor for aggregate traffic
ξt(ξs) cost for a transport module of type t(s)
kt(ks) capacity of a transport module of type t(s)
variables
xθdp flow fraction of demand d of class θ allocated to path p
uθdp flow fraction corresponding to xθdp (normalized); binary variable for the case
single path (SP) routing scheme
xdp flow fraction of demand d (aggregate) allocated to path p
udp flow fraction (normalized) corresponding to xdp for problem P2; flow fraction
(normalized) corresponding to xθdp, ∀θ for problem P3; binary variable for
the case single path (SP) routing scheme
yet(yes) number of transport modules of type t(s) on link e
case of per-aggregate routing scheme under per-aggregate OP constraints. The OP
factor for aggregate traffic is set to the maximum of per-class OP factors i.e. to the
value of 4, since the OP factor for both traffic classes has the value of 4. With this
strategy an actual minimum OP factor of 5 for aggregate traffic can be achieved by
installing 2 transport modules on each link (1, 2), (2, 4) and (4, 6). Now we will for-
mulate the problem using mathematical notations. Given a possible network topology
G = (N, E), where N is the set of nodes and E is the set of links, on which transport
modules can be installed. Let ce be defined as total link capacity installed on link e, Θ
as the set of all traffic classes, λθ
min as the actual and cOP
θ as the given minimum OP
factor for traffic class θ, per-class OP constraint can be expressed by:
λθ
min ≥ cOP
θ , ∀θ (1)
where λθ
min = mine(c∗θ
e /lθ
e), lθ
e is the load on link e contributed by θ, and c∗θ
e = ce −
θ−1
s=1 ls
e the residual link capacity available for θ, assuming that the set Θ is ordered
from high to low priority traffic (i.e. θ = 1 more important than θ = 2 · · ·). Thus,
using so-called link-path notations [13] the problem of network dimensioning using
per-class routing scheme under per-class OP constraints (denoted by P1) can be written
as follows:
5. objective:
minimize ψ =
e t
ξt · yet (2)
constraints:
d p
δedp cOP
θ · xθdp +
θ−1
i=1
xidp ≤
t
yet · kt, ∀θ, ∀e (3)
p
uθdp = 1, ∀θ, ∀d (4)
xθdp = hθd · uθdp, ∀θ, ∀d, ∀p (5)
Table 1 lists some notations which are used in the formulation. Inequality (3) defines
the capacity constraints under consideration of per-class OP factors. The equations (4)
and (5) assure that demand volume hθd is entirely routed. Using per-aggregate routing
scheme the problem of network dimensioning under per-class OP constraints (denoted
by P2) can be expressed by:
objective: (2)
constraints: (3) and
p
udp = 1, ∀d (6)
xθdp = hθd · udp, ∀θ, ∀d, ∀p (7)
Looking at the formulations above, it is clear that the problem P2 is almost identi-
cal to P1 except that (6)(7) uses aggregate routing variable udp instead of per-class
variable uθdp as in (4) and (5). Finally, the problem of network dimensioning using
per-aggregate routing scheme under per-aggregate OP constraints (denoted by P3) can
be formulated as a simple network design problem:
objective: (2)
constraints: (6) and
cOP
aggr
d p
δedp · xdp ≤
t
yet · kt, ∀e (8)
xdp = udp
θ
hθd, ∀d, ∀p (9)
Note that: (i) the constant cOP
aggr in (8) is set to maxθ{cOP
θ } in order to give a clear
comparison of the impact of per-class and per-aggregate OP constraints; and (ii) a
single path (denoted by SP) per-class (per-aggregate) routing scheme can be obtained
by constraining uθdp (udp) as a binary variable, while for a multi-path (denoted by MP)
case the variable can be an arbitrary real number between 0 and 1.
3. A HEURISTIC APPROACH
As alternative to the (M)ILP approach presented in Section 2 and since network
design problems with modular costs belong to NP problems [13], in this section we
present a flexible heuristic approach which can be used for both random as well as for
metaheuristic-based optimization frameworks. The proposed algorithm is shown in
Figure 2 and belongs to greedy heuristics in the sense that decisions for demand-path
allocation are based on the incremental cost triggered by each possible allocation. The
6. Greedy Algorithm
ψ ← 0;
loop (L1) for each d do
loop (L2) for each θ do
loop (L3) for each p do
calculate ∆ψ(p)
end (L3)
choose the cheapest path p
update the nework if necessary
establish demand d on path p
ψ ← ψ + ∆ψ(p)
end (L2)
end (L1)
Figure 2. A greedy heuristic for
network dimensioning
6
12
13
16
4
2
10
9
15
8
11
14
3
5
19
18
1
17
7
Figure 3. An example network topology
(eu35n19) used for computational studies
benefits of such heuristics for solving various design and optimization problems in the
area of communication networks have been previously investigated e.g. in [4,5]. The
algorithm starts by setting the cost ψ to zero. This can be thought of either as a green-
field approach i.e. without any existing resources or as a network expansion approach
where no cost is charged for using the existing free resources. Then for each demand
d in a certain sequence of the elements in D and for each class θ of the corresponding
demand d, the algorithm calculates the incremental costs, which are possibly caused
by the allocations of demand hθd to all considered path candidates. The demand hθd
is then allocated to (one of) the cheapest path p, the necessary transport modules are
installed, the overall cost ψ is updated and the algorithm processes the next θ or d.
Using this approach we can transform the dimensioning problems to a sequential or-
dering problem of the demands in D. The incremental cost for establishing a demand
hθd on a certain path p is the sum of the incremental costs of all links in that path,
that is ∆ψ(p) = e∈p ∆ψ(e). Before computing the incremental cost ∆ψ(e), we first
define a condition that is required in order to give benefits for using transport modules
with higher capacities. Assuming the set T is ordered from low to high capacity i.e.
kt=1 < kt=2 < · · ·, a transport module t + 1 will be used if the cost ξt+1 is lower than
the multiplication of the capacity gain kt+1/kt and the cost ξt, that is if the following
condition is fulfilled.
kt+1
kt
>
ξt+1
ξt
, ∀t ∈ {1, · · ·, |T| − 1} (10)
The incremental cost ∆ψ(e) is computed as follows. Let ψo(e) = t ξt ·yet be defined
as the total cost of transport modules currently installed on link e. Now, if by adding
7. the load hθd on e, all capacity and OP requirements are still satisfied, then ∆ψ(e) = 0
and further steps are not necessary. Otherwise a minimal number of transport modules
of type t = 1 has to be additionally installed on e, such that all OP constraints are
fulfilled. Then it has to be checked if it is necessary to replace some transport mod-
ules of lower capacity with one or more transport modules of higher capacity in order
to reduce costs. Thus, for each t ∈ {1, · · ·, |T| − 1}, the following transport mod-
ules’ replacement strategy has to repeatedly be applied for a certain t till the condition
t
s=1 ξs · yes < ξt+1 is satisfied:
if
t
s=1
ks · yes ≤ kt+1 → yes = 0, ∀s ∈ {1, · · ·, t} and ye(t+1) = ye(t+1) + 1 (11)
if (kt · yet > kt+1) → yet = yet − kt+1/kt and ye(t+1) = ye(t+1) + 1 (12)
In (12) we use the integer capacity gain kt+1/kt instead of kt+1/kt, this also re-
quires that kt+1/kt > ξt+1/ξt instead of (10). Thus, at the end we calculate the
incremental cost on link e ∈ p caused by allocation of demand hθd on path p as
∆ψ(e) = t ξt · yet − ψo(e). Note that the algorithm shown in Figure 2 is intended
for solving problem P1. For solving problem P2 and P3 the loop marked by L2 is not
necessary.
Table 2
The parameters used for case studies (a) and some computational results for network
net6 (b)
(a) Some parameters
network
net6 eu35n19
θ = 1 5.0 5.0
cOP
θ θ = 2 4.0 4.0
θ = 3 2.0 2.0
cOP
aggr 5.0 5.0
t = 1 STM-1/1.0/155 type-1/1.0/2500
name/ξt/kt t = 2 STM-4/2.5/620 type-2/2.5/10000
t = 3 STM-16/8.5/2480 type-3/8.5/40000
(b) Results for net6
problem
P1 P2 P3
cost SP 29.5 29.5 60.0
(CPLEX) MP 27.0 27.0 56.5
cost best 29.5 29.5 60.0
(greedy−
SP only− average 30.71 30.69 61.9
1000 runs)
4. RESULTS AND ANALYSIS
For our computational studies we use the networks as shown in Figure 1 (net6) and
Figure 3 (eu35n19). Network net6 consists of 6 nodes and 7 possible links, while
eu35n19 consists of 19 nodes and 35 possible links, on which transport modules may
be installed. Some constants and parameters are displayed in Table 2(a). For each net-
work, three traffic matrices (Θ = {1(premium), 2(assured), 3(best − effort)}) were
generated as follows : (i) for θ = 3, demands are randomly distributed in the interval
[10, 100] for net6 and in the interval [100, 500] for eu35n19; (ii) for net6 all demands
have a constant value of 50, θ ∈ {1, 2}; and (iii) for eu35n19 demands can have one of
the values {155, 310, 465} for θ = 2 or {310, 620} for θ = 1. Table 2(b) shows some
computational results for net6 which compares the costs obtained by CPLEX by solv-
ing the (M)ILP models for both SP and MP cases with those obtained by the proposed
heuristic for 1000 iterations. Looking at the table, it is obvious that: (i) the multi-path
8. Table 3
Results for network eu35n19
CPLEX greedy cost saving
cost gap(%) (best cost of 100 runs) (%)
problem P1 165.5 6.18 190.5 15.11
(SP only) P2 166.5 4.19 188.0 12.91
P3 423.5 3.48 453.5 7.08
(MP) routing strategy is cheaper than the single-path (SP) case for all problems; (ii)
a routing scheme based on aggregate can offer the same optimal solution with respect
to the network cost as that offered by a per-class routing scheme; (iii) deploying per-
aggregate OP constraints as in P3 can be more expensive than deploying per-class OP
constraints as in P1 and P2; and (iv) for network net6 the heuristic performs well in
the sense that it can find the optimal solutions and the differences between the average
to the optimal costs in all cases are below the value of 5%. Table 3 shows the results
for network eu35n19. CPLEX was configured to terminate if either the gap is less than
1% or the computation time of 15 hours is reached. As indicated by the gap values
in the CPLEX column, the last termination criterion is always used for all problems.
The greedy heuristic was called 100 times for each problem which corresponds to a
computation time of less than 2 minutes. The costs of the best solution resulting from
the greedy heuristic and cost savings achieved by the ILP approach are shown in the
last two columns in the table. The ILP approach can save up to 15% of the cost com-
pared to the best result from the greedy heuristic. However, this happens at the price
of significantly longer computing time.
Figure 4(a) shows the cost distribution resulting from the heuristic applied to eu35n19
for 100 iterations for the case P1 (a-i), P2 (a-ii) and P3 (a-iii). As can be seen in the
figures, the solutions for P3 in this case are also much more expensive compared to
P1 and P2. Furthermore, it seems that the heuristic performs better if we deploy per-
aggregate routing (P2) than per-class routing (P1): the best and mean cost for 4(a-ii) of
188 and 197.29 is better than that of 190.5 and 197.81 for 4(a-i). Figure 4(b) gives the
number of transport modules to be installed in the network for the best solution found
by the heuristic. The number of transport modules to be installed in P1 and P2 differ
only in an additional type-2 module, which is also indirectly expressed by the cost dif-
ference of 2.5. As the capacity requirements grow, e.g. in order to fulfill the aggregate
OP constraints in P3 case, transport modules of higher capacity are more beneficial (cf.
the cost and capacity parameters in Table 2a). This can be seen by comparing 4(b-iii)
to 4(b-ii) and 4(b-i). Finally, Figure 5 displays link utilization and OP factors for all
traffic classes for the best solution in P2 case i.e. the configuration with the number
of installed transport modules as shown in Figure 4(b-ii). The minimum aggregate
OP factor is about 1.7 which corresponds to maximum utilization of about 60%. The
values of λθ
min for each θ are (5.04; 4.00; 2.92) and thus satisfy the requirements of the
minimum values cOP
θ of (5.0; 4.0; 2.0). The minimum utilization for θ = 3 is about
4%, which happens on link numbered by 22. This explains the high value of the OP
factor for θ = 3 in Figure 5(d) for the corresponding link.
9. [190.5,193.5) [196.5,199.5) [202.5,209)
0
10
20
30
Cost Distribution
Occurance(%)
type−1 type−2 type−3
0
10
20
30
40
50
Installed Transport Modules
TotalInstalled
[188,191) [194,197) [200,205)
0
10
20
30
Occurance(%)
type−1 type−2 type−3
0
10
20
30
40
50
TotalInstalled
[453.5,459.5) [465.5,471.5) [477.5,490)
0
10
20
30
40
Occurance(%)
Cost Interval
type−1 type−2 type−3
0
10
20
30
40
50
TotalInstalled
Link Type
(a−i)
(a−ii)
(a−iii)
(b−i)
(b−ii)
(b−iii)
Figure 4. Cost distribution and number of transport modules to be installed in the
network eu35n19 for the case P1(i), P2(ii) and P3(iii) (heuristic approach)
0 5 10 15 20 25 30 35
0
10
20
30
40
50
60
70
Link Number
Utilization(%)
Link Utilization
class 1
class 2
class 3
0 5 10 15 20 25 30 35
0
2
4
6
8
10
OP Factor (class 1)
OPFactor
Link Number
0 5 10 15 20 25 30 35
0
2
4
6
8
10
OP Factor (class 2)
OPFactor
Link Number
0 5 10 15 20 25 30 35
0
5
10
15
20
OP Factor (class 3)
OPFactor
Link Number
(a) (b)
(c) (d)
min. OP
constraint
Figure 5. Link utilization and OP factors for all traffic classes for P2 case
10. 5. CONCLUDING REMARKS
In this paper we have considered the dimensioning problem for multi-class IP net-
works under per-class over-provisioning constraints. We have presented several (M)ILP
formulations and proposed a flexible greedy heuristic approach for solving the prob-
lem. Our computational experiments show that: (i) due to the known NP characteristics
for network design with modular costs, a tradeoff between solution quality and com-
putation time has to be considered; and (ii) using linear programming approach for
our sample network we can save up to 15% of the network cost compared to the result
obtained by the proposed greedy heuristic approach. The main benefit of the heuristic
is that it can find good solutions very fast. It is also very flexible in the sense that
it can be extended and combined with metaheuristic-based optimization frameworks.
Currently we are working on some different strategies for assignments of transport
modules which can improve the performance of the greedy heuristic. We are also
developing some (M)ILP models for dimensioning problems with backup capacity.
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