Efficient Data Plane Protection for SDN

Loop-free alternates and not-via addresses: A proper combination for IP fast reroute?

IP Fast Reroute (IPFRR) is resiliency technology to provide fast traffic recovery upon link or node failure for mission critical services. This technology is able to recover impacted traffic in 50 ms upon any single link or node failure. The key aspect of IP Fast Reroute technology is fast failure detection and pre-calculation of alternative path in advance, before the link or node failure occurs. If specific failure within the network occurs, IP Fast Reroute mechanism uses this pre-calculated alternative path to bypass failure and restores communication. In this paper, we bring survey of advanced Fast Reroute solutions for IP-based intra-domain networks. There have been several approaches proposed such as Directed LFA, Topology Independent LFA, BIER-TE FRR and others.

Broadcast TV distribution over an IP network requires stringent QoS constraints, such as low latency and loss. Streaming content in IPTV is typically delivered to distribution points on an IP backbone using IP multicast protocols such as Protocol Independent Multicast Source Specific Mode (PIM-SSM). Link-restoration using MPLS or layer-2 Fast Reroute (FRR) is a proven failure restoration technique. Link-based FRR creates a pseudo-wire or tunnel in parallel to the IP adjacencies (links); and thus, single link failures are transparent to the Interior Gateway Protocol (IGP) such as OSPF. Although one may choose the back-up path's IGP link weights to avoid traffic overlap during any single physical link failure, multiple failures may still cause traffic overlap with FRR. We present a cross-layer restoration approach that combines both FRR-based restoration for single link failure and “hitless” (i.e., without loss) PIM tree reconfiguration algorithms to prevent traffic overlap when multiple failures occur.

The authors develop graph-theoretical techniques using automorphisms to solve the problem of reconfiguring embedded task graphs in faulty hypercubes. Four cases are considered: single node or link failure, small number ( or=5) of random node failures. For single node (link) failure, any arbitrary task graphs embedded in a hypercube can be remapped to another instance of that graph by simple bit-flip operations. It takes at most O(n) such operations in an n-dimensional hypercube. For a small number of faults ( >

PRIMARY RETICULUM CELL SARCOMA OF THE LUNG WITH ENDOBRONCHIAL INVOLVEMENT. CASE REPORT.

Fast-recovery from link failures is a well-studied topic in IP networks. Employing fast-recovery in Ethernet networks is complicated as the forwarding is based on destination MAC addresses, which do not have the hierarchical nature similar to those exhibited in Layer 3 in the form of IP-prefixes. Moreover, switches employ backward learning to populate the forwarding table entries. Thus, any fast recovery mechanism in Ethernet networks must be based on undirected spanning trees if backward learning is to be retained. In this paper, we develop three alternatives for achieving fast recovery from single link failures in Ethernet networks. All three approaches provide guaranteed recovery from single link failures. The approaches differ in the technologies required for achieving fast recovery, namely VLAN rewrite or mac-in-mac encapsulation or both. We study the performance of the approaches developed on five different networks.

In this paper we propose a novel resilience scheme for OpenFlow-based Software-Defined Networking (SDN). To forward packets in line speed, OpenFlow switches store their flow tables in expensive, limited TCAM due to which the stored tables cannot be large. Most resilience mechanisms require additional entries thus the implementation in OpenFlow may quickly exceed the available TCAM.

Partitioning a large network into a connected hierarchy is a proven technique for scalability, manageability, and reliability. Although a significant body of works is devoted to this area of interest, a reference to partitioning schemes where each partition remains 2-connected is missing. In optical networks, a failure of a physical component disrupts multiple logical links that share the component. Such a shared risk link group (SRLG) failure is more common than a single link or node failure in the logical topology. In this paper, we introduce the k-SRLG-connected partitioning problem for optical networks, where k ≥ 1. A logical topology is said to be k-SRLG-connected if its nodes remain connected upon any k-1 SRLG failures. We particularly focus on k = 2. Without 2-SRLG-connectivity, a partition can neither provide protection by allocating two SRLG-disjoint paths, nor provide restoration after a failure. Moreover, a single SRLG failure can split the partition into multiple disconnected components, resulting in the failure of the hierarchical network organization itself. We show that finding a 2-SRLG-connected partitioning for a given network is NP-complete and provide a distributed heuristic approach. Simulation results verify that the proposed 2-SRLG-connected partitioning scheme performs better than traditional 1-connected partitioning approaches with regard to survivability and system stability.

Fault-tolerance, survivability and resiliency in wide area networks have long been prominent research topics. With the popularity of the cloud service model and the novel software defined networking (SDN) paradigm, there is renewed interest in failure protection and restoration in network service provisioning. In this work, we propose a novel protection and restoration based virtual network management scheme to enhance fault tolerance in infrastructure-as-a-service, deployed over networked cloud infrastructure. The networked cloud infrastructure is composed of multiple geographically distributed datacenters that are interconnected with SDN. Both compute and network resources are allocated by formulating the virtual network embedding problem as an integer linear program. A shared backup virtual link protection mechanism and a reactive traffic engineering network failure restoration algorithm are proposed and integrated with the framework to provide recovery from unexpected link failures. We implemented the framework on an emulated SDN testbed and evaluated the performances of the algorithms during single and multiple link failures. Experimental results demonstrate trade-offs of the proposed approaches and their applicability in different application scenarios.

To support reliable multicast routing in wireless mesh networks, it is important to protect multicast sessions against link or node failures. The issue of protecting multicast sessions in wireless mesh networks is a new problem to the best of our knowledge. In this paper, we propose a resilient forwarding mesh approach for protecting a multicast session in wireless mesh networks. Utilizing the wireless broadcast advantage, a resilient forwarding mesh effectively establishes two node disjoint paths for each source-destination pair. This allows a multicast session to be immune from any single link or intermediate node failure. We introduce four heuristic algorithms to obtain approximate solutions that seek to minimize the number of required broadcast transmissions. We evaluate the performance of these heuristic algorithms against the optimal resilient forwarding mesh (ORFM) obtained by solving an integer linear programming (ILP) formulation of the problem. Experimental results demonstrate that one of these heuristic algorithms, which we call the minimal disjoint mesh algorithm (MDM), performs sufficiently close to ORFM. Besides, we find that the resilient forwarding mesh approach provides efficient 1+ 1 protection (Pioro and Medhi, 2004) to the multicast session without incurring much additional overhead on a single minimal cost multicast tree

Recently, there is a growing interest in the applications of wireless sensor networks (WSNs). A set of sensor nodes is deployed in order to collectively survey an area of interest and/or perform specific surveillance tasks in some of the applications, such as battlefield reconnaissance. Due to the harsh deployment environments and limited energy supply, nodes may fail, which impacts the connectivity of the whole network. Since a single node failure (cut-vertex) will destroy the connectivity and divide the network into disjoint blocks, most of the existing studies focus on the problem of single node failure. However, the failure of multiple nodes would be a disaster to the whole network and must be repaired effectively. Only few studies are proposed to handle the problem of multiple cut-vertex failures, which is a special case of multiple node failures. Therefore, this paper proposes a comprehensive solution to address the problems of node failure (single and multiple). Collaborative Single Node Failure Restoration algorithm (CSFR) is presented to solve the problem of single node failure only with cooperative communication, but CSFR-M, which is the extension of CSFR, handles the single node failure problem more effectively with node motion. Moreover, Collaborative Connectivity Restoration Algorithm (CCRA) is proposed on the basis of cooperative communication and node maneuverability to restore network connectivity after multiple nodes fail. CSFR-M and CCRA are reactive methods that initiate the connectivity restoration after detecting the node failure(s). In order to further minimize the energy dissipation, CCRA opts to simplify the recovery process by gridding. Moreover, the distance that an individual node needs to travel during recovery is reduced by choosing the nearest suitable candidates. Finally, extensive simulations validate the performance of CSFR, CSFR-M and CCRA.

In this paper, we consider IP fast recovery from single-link failures in a given network topology. The basic idea is to replace some existing routers with a designated switch. When a link fails, the affected router will send all the affected traffic to the designated switch (through pre-configured IP tunnels), which will deliver the affected traffic to its destination without using the failed link. The goal of the approach is to achieve faster failure recovery than traditional routing protocols that employ reactive computing upon link failures. Software-Defined Networking (SDN) switches can serve as the designated switches because they can flexibly redirect affected traffic to other routes, instead of only to the shortest paths in the network. However, SDN switches are very expensive. Our objective is to minimize the number of SDN switches needed and to guarantee that the network can still recover from any single-link failure. For networks with uniform link costs, we show that using normal non-SDN switches with IP tunneling capability as designated switches can guarantee recovery from any single-link failure. For networks with general link costs, we find that not all single-link failures can be recovered by using non-SDN switches as designated switches; by using SDN switches only when necessary, we can reduce the total number of SDN switches needed compared to an existing work. We conduct extensive simulations to verify our proposed approaches.

A change in network topology triggers the re-convergence process of routing protocols. The re-convergence time of current routing protocols (e.g. OSPF) is constrained by the possibility of having transient loops due to the independent calculation of shortest paths between routers affected by a network failure. Several IP Fast-ReRoute (IPFRR) schemes have been developed to pro-actively calculate and install alternate forwarding entries almost instantaneously once a topology update message is received, without causing temporary micro-loops. The IPFRR scheme which has been used most extensively so far makes use of Loop-Free Alternates (LFA). While these are easy to configure, LFAs still require manual configuration, and the resulting ratio of covered link failures is only about 60 to 70 percent. This paper presents a logical extension of the Loop-Free Alternate concept, proposes a self-configuring scheme to populate the corresponding alternate entries, and evaluates the performance of the scheme with respect to coverage, configuration time and path length in a simulation environment.

We provide optimal virtual network design models with protection against various physical and virtual failures. Our models enable protection against single link, node and sub-network failures with almost the same cost using an intelligent design.

The increase in size and complexity of the Internet has led to the introduction of Software Defined Networking (SDN). SDN is a new networking paradigm that breaks the limitations of traditional IP networks and upgrades the current network infrastructures. However, like traditional IP networks, network failures may also occur in SDN. Multiple research studies have discussed this problem by using a variety of techniques. Among them is the use of the community detection method is one of the failure recovery technique for SDN. However, this technique have not considered the specific problem of multiple link multi-community failure and inter-community link failure scenarios. This paper presents a community detection-based routing algorithm (CDRA) for link failure recovery in SDN. The proposed CDRA scheme is efficient to deal with single link intra-community failure scenarios and multiple link multi-community failure scenarios and is also able to handle the inter-community link failure scenarios in SDN. Extensive simulations are performed to evaluate the performance of the proposed CDRA scheme. The simulation results depicts that the proposed CDRA scheme have better simulations results and reduce average round trip time by 35.73%, avg data packet loss by 1.26% and average end to end delay 49.3% than the Dijkstra based general recovery algorithm and also can be used on a large scale network platform.