Fast Reroute Research Articles

MOLM: Alleviating Congestion through Multi-Objective Simulated Annealing-Based Load Balancing Routing in LEO Satellite Networks

In satellite networks, existing congestion resolution methods do not consider the predictability and stability of paths, leading to frequent path switches and high maintenance costs. In this regard, we propose a novel congestion resolution approach, named MOLM, which introduces a continuous neighbor set during path updates. This set includes nodes capable of establishing sustainable connections with the predecessors and successors of congested nodes. Combined with a multi-objective simulated annealing framework, MOLM iteratively derives an optimal selection from this set to replace congested nodes. Additionally, we employ a Fast Reroute mechanism based on backup paths (FRR-BP) to address node failures. The simulation results indicate that the optimal node endows the new path with optimal path stability and path latency.

A Nationwide 400-Gbps Backbone Network for Research and Education in Japan

This paper describes the architectural design, services, and operation and monitoring functions of Science Information NETwork 6 (SINET6), a 400-Gigabit Ethernet-based academic backbone network launched on a nationwide scale in April 2022. In response to the requirements from universities and research institutions, SINET upgraded its world-class network speed, improved its accessibility, enhanced services and security, incorporated 5G mobile functions, and strengthened international connectivity. With fully-meshed connectivity and fast rerouting, it attains nationwide high performance and high reliability. The evaluation results of network performance are also reported.

Design of a Technique for Accelerating the WSN Convergence Process.

A wireless sensor network (WSN) is a network that monitors the physical environment using small and energy-efficient sensor devices. The wide application of WSNs has caused them to be used in critical applications that require a quick response, even at the cost of higher consumption. In recent years, Fast Reroute (FRR) technology has been developed, which accelerates network recovery after line or node failure. This technology plays an important role in connection recovery and data recovery, which helps speed up detection and redirect traffic. In our work, we created a new modification of the Ad hoc On-Demand Distance Vector (AODV) routing protocol, where we added the fast detection of link failure used in the FRR area. This modification rapidly increased connection recovery time and was tested in the OMNET++ simulation environment. The modification was implemented based on an additional RFC 5880 Bidirectional Forwarding Detection (BFD) module, which speeds up failure detection by sending quick "Hello" messages.

InFaRR: In-Network Fast ReRouting

InFaRR (In-network Fast ReRouting) is an algorithm for fast rerouting in programmable data planes. Implemented in P4, InFaRR is free of additional headers and network state heartbeats. InFaRR has four essential features not jointly found in other recovery mechanisms: Loop prevention, Pushback, Recognition and Restoration and Return to the main route. Tests in standard Fat-Tree and AB Fat-Tree topologies with failures in different scenarios showed positive results when compared to state-of-the-art algorithms in the literature. In scenarios in which the other algorithms were able to recover, InFaRR presented fewer hops to bypass the failure when the Pushback, Loop Prevention and Recognition and Restoration mechanisms were used. In scenarios with multiple failures, InFaRR successfully rerouted where the others algorithms in some cases looped. The mechanism for returning to the main route allows to verify failures in remote links, making it possible to return to the main route without intervention from the control plane. Several evaluations were done comparing the results of InFaRR with the state-of-the art mechanisms, showing the capability of our fast rerouting algorithm in dealing with failures at the line-rate.

Comparison of New Solutions in IP Fast Reroute

Currently, network requirements are placed on the efficiency and size of the networks. These conditions can be ensured by modern converged networks that integrate the functions of both data and telecommunication networks. Line or router failures have always been a part of transmission networks, which is no different from converged networks. As a result of outages, which can take from ms to tens of seconds, packets are lost. These outages cause degraded transmission quality, which is undesirable when transmitting real-time multimedia services (Voice over IP, video). To solve the mentioned problems, the IETF organization has developed IP Fast Reroute mechanisms to minimise the time to restore the connection after a line or node failure and, consequently, less packet loss. The article reviews and compares the latest IP Fast Reroute mechanisms deployed in the last three years. First, we have Optimistic Fast Rerouting, which calculates optimistic and fallback scenarios. The second is Post-processing Fast Reroute, which decomposes the network according to metrics such as load and route length. Third, Local Fast Reroute focused on low congestion and random access.

Existing Fast Reroute Mechanisms in SDN

Nowadays, the implementation of networks using software-defined resource environments is becoming more and more widespread. As with classic IP networks, it is necessary to consider possible complications that occur during connectivity failures (packet loss, unavailable services, congestion). A critical aspect when a connection fails is the time required to restore it. In Software-Defined Networks (SDN), where topologies are large, there are several ways to look for ways to improve network recovery speed. Fast Reroute solutions have been developed to solve negative impacts after link or node failure in SDN.This paper introduces current Fast Reroute mechanisms in Software-defined networking (SDN). The most used mechanisms include Openflow Fast Failover groups, OpenState failover technique, Loop-free Alternate (LFA) and Remote LFA (RLFA).

Fast Reroute Algorithms for Satellite Network With Segment Routing

Fast Reroute Algorithms for Satellite Network With Segment Routing

Local Fast Rerouting With Low Congestion: A Randomized Approach

Most modern communication networks include fast rerouting mechanisms, implemented entirely in the data plane, to quickly recover connectivity after link failures. By relying on local failure information only, these data plane mechanisms provide very fast reaction times, but at the same time introduce an algorithmic challenge in case of multiple link failures: failover routes need to be robust to additional but locally unknown failures downstream. This paper presents local fast rerouting algorithms which not only provide a high degree of resilience against multiple link failures, but also ensure a low congestion on the resulting failover paths. We consider a randomized approach and focus on networks which are highly connected before the failures occur. Our main contributions are three simple algorithms which come with provable guarantees and provide interesting resilience-load tradeoffs, significantly outperforming any deterministic fast rerouting algorithm with high probability.

An Improvement of an IP Fast Reroute Method Using Multiple Routing Tables

<p>The demand for high Internet availability has increased. As a routing method to recover fast from a single network component (link or node) failure, a method using multiple routing tables has been proposed. In the method, when a component failure occurs, packets which are supposed to pass through the component in the failure free state are rerouted using a backup routing table (backup table: BT) which does not use the component. Thus, it is important to decrease the increased routing cost, and because the method uses multiple BTs, it is also important to decrease the numbers of entries in BTs. In this paper, we propose a new routing method to decrease the increased routing cost. In the conventional method, there are many components that do not fail but are not used for packet forwarding in a BT. In our proposed method, we use such components as much as possible to decrease the increased routing cost. About the decreasing of the numbers of entries in BTs, we simulate packet forwarding for every node-pair and find unnecessary entries which are not used in packet forwarding in any node-pair. Numerical examples show that our proposed method is superior to the conventional method. </p> <p> </p>

Segment routing for traffic engineering and effective recovery in low-earth orbit satellite constellations

Low-Earth Orbit Satellite Constellations (LEO-SCs) provide global, high-speed, and low latency Internet access services, which bridges the digital divide in the remote areas. As inter-satellite links are not supported in initial deployment (i.e. the Starlink), the communication between satellites is based on ground stations with radio frequency signals. Due to the rapid movement of satellites, this hybrid topology of LEO-SCs and ground stations is time-varying, which imposes a major challenge to uninterrupted service provisioning and network management. In this paper, we focus on solving two notable problems in such a ground station-assisted LEO-SC topology, i.e., traffic engineering and fast reroute, to guarantee that the packets are forwarded in a balanced and uninterrupted manner. Specifically, we employ segment routing to support the arbitrary path routing in LEO-SCs. To solve the traffic engineering problem, we proposed two source routings with traffic splitting algorithms, Delay-Bounded Traffic Splitting (DBTS) and DBTS+, where DBTS equally splits a flow and DBTS ​+ ​favors shorter paths. Simulation results show that DBTS ​+ ​can achieve about 30% lower maximum satellite load at the cost of about 10% more delay. To guarantee the fast recovery of failures, two fast reroute mechanisms, Loop-Free Alternate (LFA) and LFA+, are studied, where LFA pre-computes an alternate next-hop as a backup while LFA ​+ ​finds a 2-segment backup path. We show that LFA ​+ ​can increase the percentage of protection coverage by about 15%.

Order of FIB updates seldom matters: Fast reroute and fast convergence with interface‐specific forwarding

During convergence, after a link state change in traditional networks with a distributed control plane, packets may get caught in transient forwarding loops. Such loops can be avoided by imposing a certain order among the routers in updating their forwarding information bases (FIBs), but it requires some form of coordination among routers. As an alternative, a progressive link metric increment method has been proposed for loop-free forwarding without ordered FIB updates, but it takes longer to converge to the target state. In this paper, we show that the order of updates rarely matters for loop-free convergence when the failure inference-based fast reroute (FIFR) scheme with interface-specific forwarding is employed for dealing with link failures. The key insight is to have each router install the traditional interface-independent forwarding entries as soon as they are recomputed during convergence and install the recomputed interface-specific backwarding entries post-convergence. Our evaluation of 280 real and random topologies confirms that the order of updates does not matter with the proposed approach for 17336 out of 17339 links in those topologies. To handle such rare cases where the order matters, it can be coupled with progressive link metric increments to ensure loop-freedom with unordered FIB updates. Thus, the proposed approach, referred to as FIFR++, makes it possible to achieve disruption-free fast convergence and fast reroute without requiring any modification to the IP datagram and without needing any coordination between routers.

Investigation of the Flow-Based Fast Reroute Model with Implementation of a Multimedia Quality Protection Scheme

Abstract In this paper, a tensor flow-based fast reroute model with multimedia quality protection is proposed. In the model, the conditions for implementing a multipath routing strategy and flow conservation are introduced taking into account possible packet loss at the network nodes and preventing overloading communication links both when using the primary and backup routes. At the same time, the novelty of the proposed solution is the formalization of the conditions of protection of the Quality of Experience level in terms of multimedia quality along the primary and backup routes. These conditions have been obtained during the tensor formalization of the network, which made it possible to calculate the quality of service indicators: packet loss probabilities, as well as the average end-to-end delay for audio and video flows transmitted in the multimedia session using the primary and backup routes, respectively. As a criterion for the optimality of the obtained solutions, a condition has been selected related to maximizing the overall performance of the infocommunication network. The results of the research of the proposed model confirm the adequacy of the numerical research results obtained for solving the problem of fast rerouting with link/node protection.

Efficient failure recovery techniques for segment-routed networks

In communication networks, protecting against node and link failures is an important requirement. In data networks such as IP/MPLS networks robust protection techniques have evolved, while also depending on the underlying transport networks to provide reliability. In networks such as data center networks, it is not possible to rely on the underlying layer for handling of failures. It is necessary to implement protection mechanisms with fast recovery times. Fast reroute is one such mechanism where, upon a failure, repair is initiated at the point of local repair (PLR). However, this is not efficient in terms of the operational cost of the repair. With segment-routed networks, an opportunity arises to initiate the repair at the segment endpoints and not the PLR. In this paper, we present a segment-level recovery framework, where protection is applied for each segment of an end-to-end path rather than individual links or nodes. The proposed technique is more efficient than two other existing techniques that use segment routing for recovery, namely Topology Independent Loop Free Alternate (TI-LFA) and Topology Independent Multi-Failure Alternate (TI-MFA). Simulation-based results show that the proposed scheme provides efficient failure recovery in terms of flow drop rates, ability to recover from multiple failures and resources required for the recovery. Based on these results we find that the drop rate of flows due to failure can be up to 62% lower and the increase in operational path length can be up to 35% lower resulting in more robust protection and significantly better resource utilization.

Optical Protection Cost of Loop Free Alternates on Completely Connected IP Networks Over Optical Rings

We consider protection switching in an IP over optical network. There is IP Fast Reroute Loop-free Alternates (IP FRR LFA) at the IP layer, and protection switching at the optical layer. Our network model assumes a completely connected IP network over an optical ring network that is required to protect a predetermined fraction of network bandwidth. This model leads to analytical formulas on network protection costs which we show are accurate. We also show that network cost is at or near zero when the network is required to protect at most 33% of traffic. A cost comparison to networks using MPLS Fast Reroute (MPLS FRR) further indicates that LFA is a feasible protection mechanism.

Fast ReRoute on Programmable Switches

Highly dependable communication networks usually rely on some kind of Fast Re-Route (FRR) mechanism which allows to quickly re-route traffic upon failures, entirely in the data plane. This paper studies the design of FRR mechanisms for emerging reconfigurable switches. Our main contribution is an FRR primitive for programmable data planes, PURR, which provides low failover latency and high switch throughput, by avoiding packet recirculation. PURR tolerates multiple concurrent failures and comes with minimal memory requirements, ensuring compact forwarding tables, by unveiling an intriguing connection to classic “string theory” (i.e., stringology), and in particular, the shortest common supersequence problem. PURR is well-suited for high-speed match-action forwarding architectures (e.g., PISA) and supports the implementation of a broad variety of FRR mechanisms. Our simulations and prototype implementation (on an FPGA and a Tofino switch) show that PURR improves TCAM memory occupancy by a factor of 1.5 ×- 10.8 × compared to a naïve encoding when implementing state-of-the-art FRR mechanisms. PURR also improves the latency and throughput of datacenter traffic up to a factor of 2.8 ×- 5.5 × and 1.2 ×- 2 ×, respectively, compared to approaches based on recirculating packets.

Enhanced Bit Repair IP Fast Reroute Mechanism for Rapid Network Recovery

The massive development of virtualized infrastructures, Internet of Things (IoT), and Wireless Sensor Network (WSN) in recent years has led to an increase in quality requirements for the management and reliability of underlay communication networks. Existing converged networks must therefore guarantee specific quantitative and qualitative parameters of different network communication services to meet customer requirements. However, the quality of the services operated is very negatively affected by an unpredictable failure of a communication link or a network node. In such situations, communication is typically interrupted for a period that is difficult to predict, and which can lead to significant financial losses and other negative effects. Internet Protocol Fast Reroute (IP FRR) technology was developed for these reasons. The paper presents the proposal of the new Enhanced Bit Repair (EB-REP) IP FRR mechanism, which offers significant improvements over its predecessor, the B-REP mechanism. The B-REP offers protection against a single failure and only for selected critical IP flows. The EB-REP provides advanced protection against multiple failures in a protected network domain and the protection can be provided for all network flows. The EB-REP calculates alternative paths in advance based on link metrics, but also allows the construction of alternative paths independently of them. The construction of alternative FRR paths uses a standardized tunneling approach via a unique field Bit-String. Thanks to these features, EB-REP is an advanced contribution to solving IP FRR-related problems, which enables the use of EB-REP in many network deployments, but especially in network solutions that require reliable data transmission.

Hardware-Based Evaluation of Scalable and Resilient Multicast With BIER in P4

Traditional IP multicast (IPMC) maintains state per IPMC group in core devices to distribute one-to-many traffic along tree-like structures through the network. This limits its scalability because whenever subscribers of IPMC groups change, forwarding state in the core network needs to be updated. Bit Index Explicit Replication (BIER) has been proposed by the IETF for efficient transport of IPMC traffic without the need of IPMC-group-dependent state in core devices. However, legacy devices do not offer the required features to implement BIER. P4 is a programming language which follows the software-defined networking (SDN) paradigm. It provides a programmable data plane by programming the packet processing pipeline of P4 devices. The contribution of this article is threefold. First, we provide a hardware-based prototype of BIER and BIER fast reroute (BIER-FRR) which leverages packet recirculation. Our target is the P4-programmable high-performance switching ASIC Tofino; the source code is publicly available. Second, we perform an experimental evaluation, with regard to failover time and throughput, which shows that up to 100 Gb/s throughput can be obtained and that failures affect BIER forwarding for less than 1 ms. However, throughput can decrease if switch-internal packet loss occurs due to missing recirculation capacity. As a remedy, we add more recirculation capacity by turning physical ports into loopback mode. To quantify the problem, we derive a prediction model for reduced throughput whose results are in good accordance with measured values. Third, we provide a provisioning rule for recirculation ports, that is applicable to general P4 programs, to avoid switch-internal packet loss due to packet recirculation. In a case study we show that BIER requires only a few such ports under realistic mixes of unicast and multicast traffic.

A New Bit Repair Fast Reroute Mechanism for Smart Sensors IoT Network Infrastructure.

Today’s IP networks are experiencing a high increase in used and connected Internet of Things (IoT) devices and related deployed critical services. This puts increased demands on the reliability of underlayer transport networks. Therefore, modern networks must meet specific qualitative and quantitative parameters to satisfy customer service demands in line with the most common requirements of network fault tolerance and minimal packet loss. After a router or link failure within the transport network, the network convergence process begins. This process can take an unpredictable amount of time, usually depending on the size, the design of the network and the routing protocol used. Several solutions have been developed to address these issues, where one of which is the group of so-called Fast ReRoute (FRR) mechanisms. A general feature of these mechanisms is the fact that the resilience to network connectivity failures is addressed by calculating a pre-prepared alternative path. The path serves as a backup in the event of a network failure. This paper presents a new Bit Repair (B-REP) FRR mechanism that uses a special BIER header field (Bit-String) to explicitly indicate an alternative path used to route the packet. B-REP calculates an alternative path in advance as a majority of existing FRR solutions. The advantage of B-REP is the ability to define an alternative hop-by-hop path with full repair coverage throughout the network, where, unlike other solutions, we propose the use of a standardized solution for this purpose. The area of the B-REP application is communication networks working on the principle of packet switching, which use some link-state routing protocol. Therefore, B-REP can be successfully used in the IoT solutions especially in the field of ensuring communication from sensors in order to guarantee a minimum packet loss during data transmission.

Adaptive Parameter Estimation of IIR System-Based WSN Using Multihop Diffusion in Distributed Approach

Distributed estimation of parameters in wireless sensor networks is taken into consideration to reduce the communication overhead of the network which makes the sensor system energy efficient. Most of the distributed approaches in literature, the sensor system is modeled with finite impulse response as it is inherently stable. Whereas in real time applications of WSN like target tracking, fast rerouting requires, infinite impulse response system (IIR) is used to model and that has been chosen in this work. It is assumed that every sensor node is equipped with IIR adaptive system. The diffusion least mean square (DLMS) algorithm is used to estimate the parameters of the IIR system where each node in the network cooperates themselves. In a sparse WSN, the performance of a DLMS algorithm reduces as the degree of the node decreases. In order to increase the estimation accuracy with a smaller number of iterations, the sensor node needs to share their information with more neighbors. This is feasible by communicating each node with multi-hop nodes instead of one-hop only. Therefore the parameters of an IIR system is estimated in distributed sparse sensor network using multihop diffusion LMS algorithm. The simulation results exhibit superior performance of the multihop diffusion LMS over non-cooperative and conventional diffusion algorithms.

P4-based implementation of BIER and BIER-FRR for scalable and resilient multicast

Bit Indexed Explicit Replication (BIER) is a novel IP multicast (IPMC) forwarding paradigm proposed by the IETF. It offers a transport layer for other IPMC traffic, keeps core routers unaware of IPMC groups, and utilizes a routing underlay, e.g., an IP network, for its forwarding decisions. With BIER, core networks do not require dynamic signaling and support a large number of IPMC groups with large churn rates. The contribution of this work is threefold. First, we propose a novel fast reroute (FRR) mechanism for BIER (BIER-FRR) so that IPMC traffic can be rerouted as soon as the routing underlay is able to carry traffic again after a failure. In particular, BIER-FRR enables BIER to profit from FRR mechanisms in the routing underlay. Second, we describe a prototype for BIER and BIER-FRR within an IP network with IP fast reroute (IP-FRR). It is based on the programmable data plane technology P4. Third, we propose a controller hierarchy with local controllers for local tasks, in particular to enable IP-FRR and BIER-FRR. The prototype demonstrates that BIER-FRR reduces the protection time for BIER traffic to the protection time for unicast traffic in the routing underlay.