Abstract—In order for IP to become a full-fledged carriergrade transport technology, a native IP failure-recovery scheme is necessary that can correct failures in the order of milliseconds. IP Fast ReRoute (IPFRR) intends to fill this gap, providing fast, local and proactive handling of failures right in the IP layer. Building on experiences and extensive measurement results collected with a prototype implementation of the prevailing IPFRR technique, Not-via, in this paper we identify high address management burden and computational complexity as the major causes of why commercial IPFRR deployment still lags behind, and we present a lightweight Not-via scheme, which, according to our measurements, improves these issues. Index Terms—resilience, IP fast reroute, redundant trees I.

Abstract — Wireless sensor networks (WSN) are typically employed for monitoring applications that require data collection at specific nodes, called drains. In order to improve the robustness of data collection, multiple drains may be employed. Data from every sensor is required to be logged into two distinct sensors for data collection to be resilient to any single drain failures. In this paper, we develop a routing mechanism based on colored trees. Every node forwards the packets based on the drain address and one additional bit. The number of routing table entries at each node is 2|D|, where |D | denotes the number of drains in the network. The construction of the colored trees guarantees that every node has two node-disjoint paths to two distinct drains. The running time complexity of the algorithm is O(|D||L|), where |L | denotes the number of links in the network. Through extensive simulations, we demonstrate that employing multiple drains and disjoint routing to two distinct drains reduces the average path length compared to disjoint routing to one of the multiple drains. I.

Abstract. Disjoint multipath routing (DMPR) is an effective strategy to achieve robustness in networks, where data is forwarded along multiple link- or nodedisjoint paths. DMPR poses significant challenges in terms of obtaining loopfree multiple (disjoint) paths and effectively forwarding the data over the multiple paths, the latter being particularly significant in datagram networks. One approach to reduce the number of routing table entries for multipath forwarding is to construct two trees, namely red and blue, rooted at a destination node such that the paths from a source to the destination on the two trees are link/node-disjoint. This paper develops the first distributed algorithm for constructing the colored trees whose running time is linear in the number of links in the network. The paper also demonstrates the effectiveness of employing generalized low-point concept rather than traditional low-point concept in the DFS-tree to reduce the average path lengths on the colored trees. 1

Abstract — Wireless sensor networks (WSNs) employed in monitoring applications require data collected by the sensors to be deposited at specific nodes, referred to as drains. To improve robustness in data collection, we consider a dual homing network in which two drains are employed and every node is required to send data to the two drains over link- or node-disjoint paths. One approach to reduce the number of routing table entries at a node is to construct two trees, namely red and blue, each rooted at a particular drain such that the paths from any node to the two drains on the trees are link- or node-disjoint. In this paper, we develop the first distributed algorithm for constructing colored trees in a dual-homing network whose running time is linear in the number of links. In addition, we show that the average path length may be optimized by employing the generalized low-point concept rather than the traditional low-point concept. I.

Abstract—Redundant trees are commonly used for protection and restoration in communications networks. Zhang et al. presented a linear time algorithm to compute node-redundant trees in 2-node-connected networks, which has become widely cited in the literature. In this paper, we show that it is difficult to implement this algorithm providing both correctness and linear complexity at the same time. Therefore, we present a revised algorithm with strict linear time complexity. Moreover, we generalize the concept of node-redundant trees from 2-node-connected networks to arbitrary topologies, a crucial development since real networks can not always satisfy 2-connectedness, especially after a failure. Index Terms—redundant trees; resilience I.

Abstract — Multi-path routing (MPR) is an effective strategy to achieve robustness, load balancing, congestion reduction, and increased throughput by transmitting data over multiple paths. Disjoint multi-path routing (DMPR) requires the multiple paths to be link- or node-disjoint. Implementation of both MPR and DMPR poses significant challenges in obtaining loop-free multiple (disjoint) paths and effectively forwarding the data over the multiple paths, the latter being significant in data-gram networks. In this paper, we develop a disjoint multipath routing strategy using colored trees with an objective to minimize the total cost of the routing paths in a network. Two trees, namely red and blue, rooted at a given drain is formed. We demonstrate through extensive simulations that the developed technique is extremely effective in optimizing the average cost of the paths. In addition, we also observe that the developed approach minimizes the average minimum (minimum of the two paths) cost, which is lower than that obtained by earlier algorithms. The colored tree approach simply doubles the size of the routing table when two link- or node-disjoint paths to a specific node is needed. I.

Abstract — Colored Trees (CTs) is an efficient approach to route packets along link- or node-disjoint paths in packet-switched networks. In this approach, two trees, namely red and blue, are constructed rooted at a drain such that the path from any node to the drain are link- or node-disjoint. For applications where both the trees are used simultaneously, it is critical to maintain the trees after link or node failures. To this end, this paper develops an algorithm, referred to as SimCT, that efficiently constructs and maintains colored trees under failures using only local information. Even when the entire tree needs to be recomputed, the SimCT algorithm requires 40 % lesser messages than previous techniques. The convergence time of the SimCT algorithm is linear in the number of nodes. We show through extensive simulations that the average length of the disjoint paths obtained using the SimCT algorithm is lesser compared to the previously known techniques. The above mentioned improvements are obtained by exploiting the relationship between DFS numbering, lowpoint values, and the potentials employed for maintaining partial ordering of nodes. The SimCT algorithm is also extended to obtain colored trees in multi-drain networks. I.

Abstract. In order for IP to become a full- edged carrier-grade transport technology, a native IP failure-recovery scheme is necessary that can correct failures in the order of milliseconds. IP Fast ReRoute (IPFRR) intends to ll this gap, providing fast, local and proactive handling of failures right in the IP layer. Building on experiences and extensive measurement results collected with a prototype implementation of the prevailing IPFRR technique, Not-via, in this paper we identify high address management burden and computational complexity as the major causes of why commercial IPFRR deployment still lags behind, and we present a lightweight Not-via scheme, which, according to our measurements, improves these issues.