Static routing

About: Static routing is a research topic. Over the lifetime, 25733 publications have been published within this topic receiving 576732 citations.

ESM: efficient and scalable data center multicast routing

Abstract: Multicast benefits group communications in saving network traffic and improving application throughput, both of which are important for data center applications. However, the technical trend of data center design poses new challenges for efficient and scalable multicast routing. First, the densely connected networks make traditional receiver-driven multicast routing protocols inefficient in multicast tree formation. Second, it is quite difficult for the low-end switches widely used in data centers to hold the routing entries of massive multicast groups. In this paper, we propose ESM, an efficient and scalable multicast routing scheme for data center networks. ESM addresses the challenges above by exploiting the feature of modern data center networks. Based on the regular topology of data centers, ESM uses a source-to-receiver expansion approach to build efficient multicast trees, excluding many unnecessary intermediate switches used in receiver-driven multicast routing. For scalable multicast routing, ESM combines both in-packet Bloom Filters and in-switch entries to make the tradeoff between the number of multicast groups supported and the additional bandwidth overhead. Simulations show that ESM saves 40% - 50% network traffic and doubles the application throughputs compared to receiver-driven multicast routing, and the combination routing scheme significantly reduces the number of in-switch entries required. We implement ESM on a Linux platform. The experimental results further demonstrate that ESM can well support online tree building for large-scale groups with churns, and the overhead of the combination forwarding engine is light-weighted.

Compressionless routing: a framework for adaptive and fault-tolerant routing

Abstract: Compressionless routing (CR) is an adaptive routing framework which provides a unified framework for efficient deadlock free adaptive routing and fault tolerance. CR exploits the tight coupling between wormhole routers for flow control to detect and recover from potential deadlock situations. Fault tolerant compressionless routing (FCR) extends CR to support end to end fault tolerant delivery. Detailed routing algorithms, implementation complexity, and performance simulation results for CR and FCR are presented. These results show that the hardware for CR and FCR networks is modest. Further, CR and FCR networks can achieve superior performance to alternatives such as dimension order routing. Compressionless routing has several key advantages: deadlock free adaptive routing in toroidal networks with no virtual channels, simple router designs, order preserving message transmission, applicability to a wide variety of network topologies, and elimination of the need for buffer allocation messages. Fault tolerant compressionless routing has several additional advantages: data integrity in the presence of transient faults (nonstop fault tolerance), permanent fault tolerance, and elimination of the need for software buffering and retry for reliability. The advantages of CR and FCR not only simplify hardware support for adaptive routing and fault tolerance, they also can simplify software communication layers.

On the Complexity of Optimal Request Routing and Content Caching in Heterogeneous Cache Networks

Abstract: In-network content caching has been deployed in both the Internet and cellular networks to reduce content-access delay. We investigate the problem of developing optimal joint routing and caching policies in a network supporting in-network caching with the goal of minimizing expected content-access delay. Here, needed content can either be accessed directly from a back-end server (where content resides permanently) or be obtained from one of multiple in-network caches. To access content, users must thus decide whether to route their requests to a cache or to the back-end server. In addition, caches must decide which content to cache. We investigate two variants of the problem, where the paths to the back-end server can be considered as either congestion-sensitive or congestion-insensitive, reflecting whether or not the delay experienced by a request sent to the back-end server depends on the request load, respectively. We show that the problem of optimal joint caching and routing is NP-complete in both cases. We prove that under the congestion-insensitive delay model, the problem can be solved optimally in polynomial time if each piece of content is requested by only one user, or when there are at most two caches in the network. We also identify the structural property of the user-cache graph that makes the problem NP-complete. For the congestion-sensitive delay model, we prove that the problem remains NP-complete even if there is only one cache in the network and each content is requested by only one user. We show that approximate solutions can be found for both cases within a $(1-1/e)$ factor from the optimal, and demonstrate a greedy solution that is numerically shown to be within 1% of optimal for small problem sizes. Through trace-driven simulations, we evaluate the performance of our greedy solutions to joint caching and routing, which show up to 50% reduction in average delay over the solution of optimized routing to least recently used caches.

A tradeoff between space and efficiency for routing tables

Abstract: Two conflicting goals play a crucial role in the design of routing schemes for communication networks. A routing scheme should use as short as possible paths for routing messages in the network, while keeping the routing information stored in the processors' local memory as succinct as possible. The efficiency of a routing scheme is measured in terms of its stretch factor - the maximum ratio between the length of a route computed by the scheme and that of a shortest path connecting the same pair of vertices.Most previous work has concentrated on finding good routing schemes (with a small fixed stretch factor) for special classes of network topologies. In this work we study the problem for general networks, and look at the entire range of possible stretch factors. The results exhibit a tradeoff between the efficiency of a routing scheme and its space requirements. We present almost tight upper and lower bounds for this tradeoff. Specifically, we prove that any routing scheme for general n-vertex networks that achieves a stretch factor k ≥ 1 must use a total of O(n1+1/2k+4) bits of routing information in the networks. This lower bound is complemented by a family H(k) of hierarchical routing schemes (for every fixed k ≥ 1), which guarantee a stretch factor of O(k), require storing a total of O(n1+1/k) bits of routing information in the network and name the vertices with O(log2n)-bit names.