Router Forwarding Research Articles

A congestion control scheme based on path recovery for smart grid communication

In order to solve the problem that the original path forwarding traffic caused by congestion that cannot be recovered in time in Smart Grid Communication, a congestion control scheme RFCC (Router Forwarding Congestion Control) based on path recovery is proposed, which not only supports the receiving end combined with router nodes to relieve congestion, it can also solve the problem of low transmission performance caused by not being able to restore the original path in time after the traffic is transferred. Active queue management technology is used to detect congestion and notify downflow nodes (users and routers) in time, which trigger downflow users to adjust the request sending window and intermediate routers to transfer packets. In addition, the original path traffic is restored in time through the path recovery policy. Firstly, the path traffic is recovered according to the congestion mark carried by the subsequent content packets. Secondly, the transmission frequency of the probe packets is calculated according to the information such as the packet queue length of routers and the available bandwidth of the congested path, and the probe packets are periodically sent to the congested path, and the traffic is sent to the congested path in time. The alternate path is transferred back to the original path. This paper implements the scheme in NS-3, and extensive experiments show that the proposed scheme outperforms the comparison schemes, which not only higher and more stable throughput can be obtained, but also shorter and more stable transmission delay can be obtained. In addition, the optimal path transmission volume and link utilization are improved.

Packet Loss Optimization in Router Forwarding Tasks Based on the Particle Swarm Algorithm

Software-defined networks (SDNs) are computer networks where parameters and devices are configured by software. Recently, artificial intelligence aspects have been used for SDN programs for various applications, including packet classification and forwarding according to the quality of service (QoS) requirements. The main problem is that when packets from different applications pass through computer networks, they have different QoS criteria. To meet the requirements of packets, routers classify these packets, add them to multiple weighting queue systems, and forward them according to their priorities. Multiple queue systems in routers usually use a class-based weighted round-robin (CBWRR) scheduling algorithm with pre-configured fixed weights for each priority queue. The problem is that the intensity of traffic in general and of each packet class occasionally changes. Therefore, in this work, we suggest using the particle swarm optimization algorithm to find the optimal weights for the weighted fair round-robin algorithm (WFRR) by considering the variable densities of the traffic. This work presents a framework to simulate router operations by determining the weights and schedule packets and forwarding them. The proposed algorithm to optimize the weights is compared with the conventional WFRR algorithm, and the results show that the particle swarm optimization for the weighted round-robin algorithm is more efficient than WFRR, especially in high-intensity traffic. Moreover, the average packet-loss ratio does not exceed 7%, and the proposed algorithms are better than the conventional CBWRR algorithm and the related work results.

Cache management for large data transfers and multipath forwarding strategies in Named Data Networking

Named Data Networking (NDN) is a promising approach to provide fast in-network access to compact muon solenoid (CMS) datasets. It proposes a content-centric rather than a host-centric approach to data retrieval. Data packets with unique and immutable names are retrieved from a content store (CS) using Interest packets. The current NDN architecture relies on forwarding strategies that are only dependent upon on-path caching. Such a design does not take advantage of the cached content available on the adjacent off-path routers in the network, thus reducing data transfer efficiency. In this work, we propose a software-defined, storage-aware routing mechanism that leverages NDN router cache-states, software defined networking (SDN) and multipath forwarding strategies to improve the efficiency of very large data transfers. First, we propose a novel distributed multipath (D-MP) forwarding strategy and enhancements to the NDN Interest forwarding pipeline. In addition, we develop a centralized SDN-enabled control for the multipath forwarding strategy (S-MP), which leverages the global knowledge of NDN network states that distributes Interests efficiently. We perform extensive evaluations of our proposed methods on an at-scale wide area network (WAN) testbed spanning six geographically separated sites. Our proposed solutions easily outperform the existing NDN forwarding strategies. The D-MP strategy results in performance gains ranging between 10.4x to 12.5x over the default NDN implementation without in-network caching, and 12.2x to 18.4x with in-network caching enabled. For S-MP strategy, we demonstrate a performance improvement of 10.6x to 12.6x, and 12.9x to 18.5x, with in-network caching disabled and enabled, respectively. Further, we also present a comprehensive analysis of NDN cache management for large data transfers and propose a novel prefetching mechanism to improve data transfer performance. Due to the inherent capacity limitations of the NDN router caches, we use SDN to provide an intelligent and efficient solution for data distribution and routing across multiple NDN router caches. We demonstrate how software-defined control can be used to partition and distribute large CMS files based on NDN router cache-state knowledge. Further, SDN control will also configure the router forwarding strategy to retrieve CMS data from the network. Our proposed solution demonstrates that the CMS datasets can be retrieved 28%–38% faster from the NDN routers’ caches than existing NDN approaches. Lastly, we develop a prefetching mechanism to improve the transfer performance of files that are not available in the router’s cache.

FISE: A Forwarding Table Structure for Enterprise Networks

With increasing demands for more flexible services, the routing policies in enterprise networks become much richer. This has placed a heavy burden to the current router forwarding plane in support of the increasing number of policies, primarily due to the limited capacity in TCAM, which further hinders the development of new network services and applications. The scalable forwarding table structures for enterprise networks have therefore attracted numerous attentions from both academia and industry. To tackle this challenge, in this paper we present the design and implementation of a new forwarding table structure. It separates the functions of TCAM and SRAM, and maximally utilizes the large and flexible SRAM. A set of schemes are progressively designed, to compress storage of forwarding rules, and maintain correctness and achieve line-card speeds of packet forwarding. We further design an incremental update algorithm that allows less access to memory. The proposed scheme is validated and evaluated through a realistic implementation on a commercial router using real datasets. Our proposal can be easily implemented in the existing devices. The evaluation results show that the performance of forwarding tables under the proposed scheme is promising.

High-Throughput Link-Channel Selection and Power Allocation in Wireless Mesh Networks

Varying channel conditions, dynamic traffic flows, interference and congestion are the main challenges to achieve high-throughput data delivery in multi-radio multi-channel Wireless Mesh Networks (WMNs). The performance of existing solutions are limited either for using statically computed end-to-end relay paths or myopic forwarding decisions. In this paper, we consider the problem of high-throughput traffic forwarding that involves good quality link selection, channel allocation and power control at each forwarding router. Every router chooses a set of outgoing link-channel pairs and their power allocations through a mixed-integer-non-linear programming (MINLP) solution that maximizes its sum total outgoing flow rate while keeping interference and congestion at minimum. Since, the MINLP optimization function is an NP-hard one, a Reinforcement learning based system for Link-Channel selection and Power allocation, namely RLCP, is developed. A comprehensive design of the RLCP system has been presented containing portrayal of the system state, design of a reputation metric and a mechanism to learn the control policy. We have carried out exhaustive simulations on NS-3 and found the proposed RLCP system to prove its efficacy in terms of aggregated throughput, flow fairness and packet delivery delay.

Traffic engineering in cognitive mesh networks: Joint link-channel selection and power allocation

In this paper, we investigate traffic engineering (TE) methods in Cognitive Radio Wireless Mesh Networks (CR-WMNs) through joint selection of link-channel pairs at each forwarding router and allocating powers on those so as to boost up overall network throughput. We first present an optimization framework, Centralized Optimal Traffic Engineering (COTE), aiming at maximizing aggregated network throughput by selecting optimal set of link-channel pairs, power allocation over those and fair traffic splitting. Further, a centralized Suboptimal Traffic Engineering (SOTE) solution is proposed by employing Lagrangian dual decomposition on the COTE problem, to ensure a resolution in polynomial time. Finally, a Distributed Greedy Traffic Engineering (DGTE) method is proposed to ensure fast convergence to the dynamic changing network behavior and to improve scalability. Extensive simulation results are presented to demonstrate the effectiveness of our proposed TE mechanisms compared to the state-of-the-art works.

Matching circuits can be small: Partial evaluation and reconfiguration for FPGA-based packet processing

Network functions like routing or firewalling require specialized hardware such as FPGAs to process packets at high rates. Such hardware must be fast enough to process packets at line rate, and it must be programmable to update the installed packet processing policy. However, these goals are conflicting because a generic programmable circuit must provide sufficient resources to support a wide range of policies, which can lead to unused circuitry and low clock rates. Also, it misses logic optimization opportunities with regard to the structure of the installed policy. In this work, we investigate the optimization potential of policy-specific generated network processing circuits. Using the example of router forwarding information bases (FIBs), we demonstrate that FIB-specialized circuits need significantly fewer logic resources than equivalent generic forwarding circuits. In combination with the partial reconfiguration capability of FPGAs, we obtain efficient low-latency forwarding engines whose matching circuitry can be replaced on demand.

Efficient quality of service‐aware packet chunking scheme for machine‐to‐machine cloud services

SummaryWith the recent advances in machine‐to‐machine communications, huge numbers of devices have become connected and massive amounts of traffic are exchanged. Machine‐to‐machine applications typically generate small packets, which can profoundly affect the network performance. Namely, even if the packet arrival rate at the router is lower than the link bandwidth, bits per second, it can exceed the router forwarding capacity, which indicates the maximum number of forwarded packets per second. This will cause the decrease in the network throughput. Therefore, eliminating the packets per second limitation by chunking small packets will enable machine‐to‐machine cloud services to spread further. This paper proposes new packet‐chunking schemes aimed at meeting both application requirements and improving achievable router throughput. In our schemes, multiple buffers, each of which accommodates packets classified based on their delay requirement, are installed in parallel. Herein, we report on analysis of the theoretically performance of these schemes, which enabled us to derive some important features. We also propose a scheme whereby a single chunking buffer and parallel multiple buffers were arranged in tandem. Through our simulation and numerical results, we determined that these schemes provide excellent performance in reducing the number of outgoing packets from the router while meeting various delay requirements.

QuLa: Queue and latency-aware service selection and routing in service-centric networking

Due to an explosive growth in services running in different datacenters, there is need for service selection and routing to deliver user requests to the best service instance. In current solutions, it is generally the client that must first select a datacenter to forward the request to before an internal load-balancer of the selected datacenter can select the optimal instance. An optimal selection requires knowledge of both network and server characteristics, making clients less suitable to make this decision. Information-Centric Networking (ICN) research solved a similar selection problem for static data retrieval by integrating content delivery as a native network feature. We address the selection problem for services by extending the ICN-principles for services. In this paper we present Queue and Latency, a network-driven service selection algorithm which maps user demand to service instances, taking into account both network and server metrics. To reduce the size of service router forwarding tables, we present a statistical method to approximate an optimal load distribution with minimized router state required. Simulation results show that our statistical routing approach approximates the average system response time of source-based routing with minimized state in forwarding tables.

Contrace: a tool for measuring and tracing content-centric networks

Content-Centric Networks (CCNs) are fundamental evolutionary technologies that promise to form the cornerstone of the future Internet. The information flow in these networks is based on named data requesting, in-network caching, and forwarding, which are unique and can be independent of IP routing. As a result, common IP-based network tools such as ping and traceroute can neither trace a forwarding path in CCNs nor feasibly evaluate CCN performance. We propose “contrace,” a network tool for CCNs (particularly, CCNx implementation running on top of IP) that can be used to investigate the round-trip time (RTT) between content forwarder and consumer, the states of in-network cache per name prefix, and the forwarding path information per name prefix. We report a series of experiments conducted using contrace on a CCN topology created on a local testbed and the GEANT network topology emulated by the Mini-CCNx emulator. The results confirm that contrace is not only a useful tool for monitoring and operating a network, but also a helpful analysis tool for enhancing the design of CCNs. Further, contrace can report the number of received interests per cache or per chunk on the forwarding routers. This enables us to estimate the content popularity and design more effective cache control mechanisms in experimental networks.

Towards Attacks and Defenses of Anonymous Communication Systems

Anonymous communication system has been hot topic in the field of information security, and attack techniques against anonymous systems are endless. This paper first classifies and summarizes the study of attacks against anonymous communication system in recent years, then analyzes the trend of the research on different attack technologies; secondly, it provides a comparative analysis of defense capability the mainstream anonymous communication system to the various attacks; Finally, combining the advantages and disadvantages of different systems, the authors propose an improved node selection and router forwarding algorithms for anonymous communication systems, and design an architecture of anonymous communications software based on the algorithm.

Analyzing the Effect of Varying CBR on AODV, DSR, IERP Routing Protocols in MANET

Mobile Ad Hoc Networks (MANET) are wireless networks which do not require any infrastructure support for transferring data packet between two nodes. Mobile ad-hoc network have the attributes such as wireless connection, continuously changing topology, distributed operation and ease of deployment. The mobile nodes perform both as a host and a router forwarding packets to other nodes. Routing in these networks is highly complex. It can be used for various applications areas as sensor applications, disaster management, conferences, rescue operations, military communications, hybrid wireless network architectures and wireless mesh networks and many more. Traditional routing mechanism and protocol of wired network are inapplicable to ad-hoc networks which initiated the need of a dynamic routing mechanism in ad-hoc network. This paper evaluates the performance of AODV, DSR (Reactive) and IERP (Hybrid) routing protocols with respect to varying Constant Bit Rate (CBR). A detailed simulation has been carried out in QualNet Simulator 6.1. The performance analysis is based on different network metrics such as Average End to End delay, Throughput, Average Jitter, Packet Delivery Ratio. Keywords: AODV, DSR, IERP, Mobile Ad-hoc networks, QualNet 6.1

Effect of Traffic Pattern on Packet Delivery Ratio in Reactive Routing Protocol of Manet

An ad hoc network is a collection of mobile nodes that dynamically form a temporary network. Routing in a MANET is challenging because of the dynamic topology and the lack of an existing fixed infrastructure. In such a scenario a mobile host can act as both a host and a router forwarding packets for other mobile nodes in the network. Routing protocols used in mobile ad hoc networks (MANET) must adapt to frequent or continual changes of topology, while simultaneously limiting the impact of tracking these changes on wireless resources. In his paper investigation has been done on the effect of change in number of nodes, node speed and pause time on packet delivery ratio (PDR) of MANET reactive routing protocols. Here, it has been analyzed and compared the performance of MANET routing protocols AODV and DSR based on both CBR and TCP based traffic patterns. The NS-2 simulator is used for performing various simulations and used awk scripts for analyzing the results. AODV in the simulation experiment shows the overall best performance. It has an improvement over DSR.

Performance analysis of Dynamic MANET Ondemand (DYMO) Routing protocol

Routing in a MANET is challenging because of the dynamic topology and the lack of an existing fixed infrastructure. In such a scenario a mobile host can act as both a host and a router forwarding packets for other mobile nodes in the network. Routing protocols used in mobile ad hoc networks (MANET) must adapt to frequent or continual changes of topology, while simultaneously limiting the impact of tracking these changes on wireless resources. The DYMO protocol intended for the use by mobile nodes in wireless multihop ad hoc networks. It can adapt to the changing network topology and determine unicast routes between nodes within the network. This paper presents a comprehensive summarization and a comparative study of the Dynamic MANET On-demand (DYMO) protocol for MANET and simulation analysis of existing protocols DSR and AODV and comparison among them under varying number of nodes. Comparative study shows that DYMO is only a good choice if the nodes are mobile and wireless multihop. We have compared the performance of DSR and AODV with DYMO protocol by taking some performance metrics. Result shows that DYMO simulation provides better performance than DSR when compared in a given network topology with respect to throughput, packet loss, delay, packet delivery ratio, normalized routing load.

Low-Power TCAMs for Very Large Forwarding Tables

Ternary content-addressable memories (TCAMs) may be used to obtain a simple and very fast implementation of a router's forwarding engine. The applicability of TCAMs is, however, limited by their size and high power requirement. Zane et al. proposed a method and associated algorithms to reduce the power needed to search a forwarding table using a TCAM. We improve on both the algorithms proposed by them. Additionally, we show how to couple TCAMs and high-bandwidth SRAMs so as to overcome both the power and size limitations of a pure TCAM forwarding engine. By using one of our novel TCAM-SRAM coupling schemes (M-12 Wb), we are able to reduce TCAM memory by a factor of about 5 on IPv4 data sets and by a factor of about 2.5 on IPv6 data sets; TCAM power requirement is reduced by a factor of about 10 on IPv4 data sets and by a factor of about 6 on IPv6 data sets. These comparisons are with respect to the improved TCAM algorithms we have developed for the strategies of Zane et al. The stated improvements come at the cost of increasing SRAM requirement by a factor 2.5 for IPv4 data and a factor of 5 for IPv6 data. This cost is unimportant given that SRAMs are relatively quite cheap and have much less power requirement. For another of our novel TCAM-SRAM coupling schemes (1-12Wc), the TCAM memory and power reduced by factors of about 4 and 12 for IPv4 data sets, respectively, and by factors of about 2 and 10 for IPv6 data sets. The SRAM required, however, increased by factors of 3 and 7, respectively. These improvements come with no loss in the time (as measured by the number of TCAM searches and SRAM accesses) to do a lookup.

Parallelism versus Memory Allocation in Pipelined Router Forwarding Engines

A crucial problem that needs to be solved is the allocation of memory to processors in a pipeline. Ideally, the processor memories should be totally separate (i.e., one-port memories) in order to minimize contention; however, this minimizes memory sharing. Idealized sharing occurs by using a single shared memory for all processors but this maximizes contention. Instead, in this paper we show that perfect memory sharing of shared memory can be achieved with a collection of two-port memories, as long as the number of processors is less than the number of memories. We show that the problem of allocation is NP-complete in general, but has a fast approximation algorithm that comes within a factor of $\frac 32$ asymptotically. The proof utilizes a new bin packing model, which is interesting in its own right. Further, for important special cases that arise in practice a more sophisticated modification of this approximation algorithm is in fact optimal. We also discuss the online memory allocation problem and present fast online algorithms that provide good memory utilization while allowing fast updates.

Benefits of label stripping compared to label swapping from the point of node dimensioning

All-Optical Label Swapping (AOLS) is a promising packet-switching technology to accomplish the gap between router forwarding speed and fibre transmission speed. The hardware requirements from the node however are unarguable a big disadvantage of these kinds of nodes. In this paper, we present two all-optical label switching nodes. One is based on the MPLS technology and one is an alternative switching strategy for packet-switching: label stripping. We compare both node architectures in terms of hardware requirements for different switching strategies and network parameters (such as topology and number of nodes).

Proactive Handover Scheme Based on Forwarding Router Discovery for Mobile IP Networks

One of the main issues of Mobile IPv6 is handover latency that causes service disruption time. Although plenty of proposals significantly reduce the service disruption time, they suffer from redundant routing that causes packet misordering and bandwidth consumption during the process of inter-domain handover. In this paper, we propose a new scheme that minimizes the redundant routing during the process of inter-domain handover by utilizing forwarding routers for each correspondent node. Our proposed scheme consists of forwarding router discovery and proactive handover. We evaluate our proposed scheme in the view of packet misordering and bandwidth consumption, and clarify the efficiency of our proposed scheme. We also evaluate the impact of the forwarding routers' capacity since routers have limited resources. By strategically locating forwarding routers, e.g. next to the router that has peering to another domain, the redundant routing caused by inter-domain handover will be efficiently suppressed.

Novel hardware architecture for fast address lookups

For every packet an IP router receives, it makes a routing decision based on the packet's destination address. The router's forwarding rate is usually limited by the rate at which it can make these decisions. We describe a new method for implementing route lookups in hardware. Our method can be implemented in the forwarding engine of a network processor or router using a small on-chip SRAM and an off-chip DRAM, and it achieves a rate of one lookup per DRAM random access time. We present our method and discuss an implementation that uses a DRAM with 64 ns random access time to give over 15 million lookups per second. Our tests show that the method performs well for realistic routing tables while using only modest amounts of memory.

Control-on-demand: an efficient approach to router programmability

Control-on-demand is a paradigm for network programmability at the network transport level. Prior work on active and programmable networking at this level either achieves flexibility by inserting significant software in the critical path of forwarding or achieves efficiency by sacrificing functionality and relegating programmability to connection management. In contrast, control-on-demand acts both in the control plane and in the data plane, still without adding software in the critical forwarding path. Rather than applying essential programs to every datagram, our approach is to apply the installed service logic asynchronously from data forwarding. This way we avoid essential processing in the critical forwarding path, applying the (user) installed service logic for service enhancement only. In this paper, we describe control-on-demand and how its service model provides sufficient richness to act in the data path. Set is restrictive enough to avoid the significant performance overhead of other in-data path approaches. The expressiveness of the programmable model is limited to observing and suggesting to the forwarding engine, but is never essential for correct processing, thus significantly reducing security and robustness concerns. Consequently, control-on-demand is efficient enough to make it viable for elementary services. Rather than replacing the interoperability layer, control-on-demand represents an evolution of router (switch) control functionality. As the required modification of router forwarding engines is insignificant, control-on-demand is viable in practice in the near future. These concepts have been prototyped as part of the Pronto Control Platform. In this paper, we describe our IPv6 router prototype implementation and discuss the application of control-on-demand on a number of interesting problems.