Showing papers on "Routing table published in 2004"

Tapestry: a resilient global-scale overlay for service deployment

Abstract: We present Tapestry, a peer-to-peer overlay routing infrastructure offering efficient, scalable, location-independent routing of messages directly to nearby copies of an object or service using only localized resources. Tapestry supports a generic decentralized object location and routing applications programming interface using a self-repairing, soft-state-based routing layer. The paper presents the Tapestry architecture, algorithms, and implementation. It explores the behavior of a Tapestry deployment on PlanetLab, a global testbed of approximately 100 machines. Experimental results show that Tapestry exhibits stable behavior and performance as an overlay, despite the instability of the underlying network layers. Several widely distributed applications have been implemented on Tapestry, illustrating its utility as a deployment infrastructure.

Routing in a delay tolerant network

Abstract: We formulate the delay-tolerant networking routing problem, where messages are to be moved end-to-end across a connectivity graph that is time-varying but whose dynamics may be known in advance. The problem has the added constraints of finite buffers at each node and the general property that no contemporaneous end-to-end path may ever exist. This situation limits the applicability of traditional routing approaches that tend to treat outages as failures and seek to find an existing end-to-end path. We propose a framework for evaluating routing algorithms in such environments. We then develop several algorithms and use simulations to compare their performance with respect to the amount of knowledge they require about network topology. We find that, as expected, the algorithms using the least knowledge tend to perform poorly. We also find that with limited additional knowledge, far less than complete global knowledge, efficient algorithms can be constructed for routing in such environments. To the best of our knowledge this is the first such investigation of routing issues in DTNs.

Measuring ISP topologies with Rocketfuel

Abstract: To date, realistic ISP topologies have not been accessible to the research community, leaving work that depends on topology on an uncertain footing. In this paper, we present new Internet mapping techniques that have enabled us to measure router-level ISP topologies. Our techniques reduce the number of required traces compared to a brute-force, all-to-all approach by three orders of magnitude without a significant loss in accuracy. They include the use of BGP routing tables to focus the measurements, the elimination of redundant measurements by exploiting properties of IP routing, better alias resolution, and the use of DNS to divide each map into POPs and backbone. We collect maps from ten diverse ISPs using our techniques, and find that our maps are substantially more complete than those of earlier Internet mapping efforts. We also report on properties of these maps, including the size of POPs, distribution of router outdegree, and the interdomain peering structure. As part of this work, we release our maps to the community.

Comparison of routing metrics for static multi-hop wireless networks

Abstract: Routing protocols for wireless ad hoc networks have traditionally focused on finding paths with minimum hop count. However, such paths can include slow or lossy links, leading to poor throughput. A routing algorithm can select better paths by explicitly taking the quality of the wireless links into account. In this paper, we conduct a detailed, empirical evaluation of the performance of three link-quality metrics---ETX, per-hop RTT, and per-hop packet pair---and compare them against minimum hop count. We study these metrics using a DSR-based routing protocol running in a wireless testbed. We find that the ETX metric has the best performance when all nodes are stationary. We also find that the per-hop RTT and per-hop packet-pair metrics perform poorly due to self-interference. Interestingly, the hop-count metric outperforms all of the link-quality metrics in a scenario where the sender is mobile.

Topology Dissemination Based on Reverse-Path Forwarding (TBRPF)

Abstract: Topology Dissemination Based on Reverse-Path Forwarding (TBRPF) is a proactive, link-state routing protocol designed for mobile ad-hoc networks, which provides hop-by-hop routing along shortest paths to each destination. Each node running TBRPF computes a source tree (providing paths to all reachable nodes) based on partial topology information stored in its topology table, using a modification of Dijkstra's algorithm. To minimize overhead, each node reports only *part* of its source tree to neighbors. TBRPF uses a combination of periodic and differential updates to keep all neighbors informed of the reported part of its source tree. Each node also has the option to report additional topology information (up to the full topology), to provide improved robustness in highly mobile networks. TBRPF performs neighbor discovery using "differential" HELLO messages which report only *changes* in the status of neighbors. This results in HELLO messages that are much smaller than those of other link-state routing protocols such as OSPF.

A routing scheme for content-based networking

Abstract: This work proposes a routing scheme for content-based networking. A content-based network is a communication network that features a new advanced communication model where messages are not given explicit destination addresses, and where the destinations of a message are determined by matching the content of the message against selection predicates declared by nodes. Routing in a content-based network amounts to propagating predicates and the necessary topological information in order to maintain loop-free and possibly minimal forwarding paths for messages. The routing scheme we propose uses a combination of a traditional broadcast protocol and a content-based routing protocol. We present the combined scheme and its requirements over the broadcast protocol. We then detail the content-based routing protocol, highlighting a set of optimization heuristics. We also present the results of our evaluation, showing that this routing scheme is effective and scalable.

A-STAR: A Mobile Ad Hoc Routing Strategy for Metropolis Vehicular Communications

Abstract: One of the major issues that affect the performance of Mobile Ad hoc NETworks (MANET) is routing. Recently, position-based routing for MANET is found to be a very promising routing strategy for inter-vehicular communication systems (IVCS). However, position-based routing for IVCS in a built-up city environment faces greater challenges because of potentially more uneven distribution of vehicular nodes, constrained mobility, and difficult signal reception due to radio obstacles such as high-rise buildings. This paper proposes a new position-based routing scheme called Anchor-based Street and Traffic Aware Routing (A-STAR), designed specifically for IVCS in a city environment. Unique to A-STAR is the usage of information on city bus routes to identify an anchor path with high connectivity for packet delivery. Along with a new recovery strategy for packets routed to a local maximum, the proposed protocol shows significant performance improvement in a comparative simulation study with other similar routing approaches.

Efficient routing for peer-to-peer overlays

Abstract: Most current peer-to-peer lookup schemes keep a small amount of routing state per node, typically logarithmic in the number of overlay nodes. This design assumes that routing information at each member node must be kept small, so that the bookkeeping required to respond to system membership changes is also small, given that aggressive membership dynamics are expected. As a consequence, lookups have high latency as each lookup requires contacting several nodes in sequence. In this paper, we question these assumptions by presenting two peer-to-peer routing algorithms with small lookup paths. First, we present a one-hop routing scheme. We show how to disseminate information about membership changes quickly enough so that nodes maintain accurate routing tables with complete membership information. We also deduce analytic bandwidth requirements for our scheme that demonstrate its feasibility. We also propose a two-hop routing scheme for large scale systems of more than a few million nodes, where the bandwidth requirements of one-hop routing can become too large. This scheme keeps a fixed fraction of the total routing state on each node, chosen such that the first hop has low latency, and thus the additional delay is small. We validate our analytic model using simulation results that show that our algorithms can maintain routing information sufficiently up-to-date such that a large fraction (e.g., 99%) of the queries will succeed without being re-routed.

The case for separating routing from routers

Abstract: Over the past decade, the complexity of the Internet's routing infrastructure has increased dramatically. This complexity and the problems it causes stem not just from various new demands made of the routing infrastructure, but also from fundamental limitations in the ability of today's distributed infrastructure to scalably cope with new requirements.The limitations in today's routing system arise in large part from the fully distributed path-selection computation that the IP routers in an autonomous system (AS) must perform. To overcome this weakness, interdomain routing should be separated from today's IP routers, which should simply forward packets (for the most part). Instead, a separate Routing Control Platform (RCP) should select routes on behalf of the IP routers in each AS and exchange reachability information with other domains.Our position is that an approach like RCP is a good way of coping with complexity while being responsive to new demands and can lead to a routing system that is substantially easier to manage than today. We present a design overview of RCP based on three architectural principles path computation based on a consistent view of network state, controlled interactions between routing protocol layers, and expressive specification of routing policies and discuss the architectural strengths and weaknesses of our proposal.

Method for configuring and routing data within a wireless multihop network and a wireless network for implementing the same

Abstract: A method for configuring a wireless data packet network comprising a control node and multiple individual nodes includes the following steps: organizing the network into multiple bands Bi each band including individual nodes located i hops away from the control node; assigning a logical address to each individual node. A routing logical address is added to every data packet and each individual node compares its own logical address to the routing address of a received packet. In dependence on the result of the comparison, the packet is discarded, re-transmitted or processed in the node. The network is preferably a packet-hopping wireless network in which data packets are transferred from node to node over a common RF channel.

Maximum lifetime routing in wireless ad-hoc networks

Abstract: Routing problems in mobile ad-hoc networks (MANET) have been receiving increasing attention in the last few years. Most of the proposed routing protocols concentrate on finding and maintaining routes in the face of changing topology caused by mobility or other environmental changes. More recently, power-aware routing protocols and topology control algorithms have been developed to address the issue of limited energy reserve of the nodes in ad-hoc networks. We consider the routing problem in MANET with the goal of maximizing the life time of the network. We propose a distributed routing algorithm that reaches the optimal (centralized) solution to within an asymptotically small relative error. Our approach is based on the formulation of multicommodity flow, and it allows to consider different power consumption models and bandwidth constraints. It works for both static and slowly changing dynamic networks.

Longest prefix match lookup using hash function

Abstract: A method and apparatus are used for finding the longest prefix match in a variable length prefix search when searching a direct table within a routing table structure of a network processor. The search through the routing table structure is expedited by hashing a first segment of an internet protocol address with a virtual private network number followed by concatenating the unhashed bits of the IP address to the result of the hash operation to form an input key. Patterns are compared a bit at a time until an exact match or the best match is found. The search is conducted in a search tree that provides that the matching results will be the best possible match.

BeeHive: An efficient fault-tolerant routing algorithm inspired by honey bee behavior

Abstract: Bees organize their foraging activities as a social and communicative effort, indicating both the direction, distance and quality of food sources to their fellow foragers through a ”dance” inside the bee hive (on the ”dance floor”). In this paper we present a novel routing algorithm, BeeHive, which has been inspired by the communicative and evaluative methods and procedures of honey bees. In this algorithm, bee agents travel through network regions called foraging zones. On their way their information on the network state is delivered for updating the local routing tables. BeeHive is fault tolerant, scalable, and relies completely on local, or regional, information, respectively. We demonstrate through extensive simulations that BeeHive achieves a similar or better performance compared to state-of-the-art algorithms.

Dynamics of hot-potato routing in IP networks

Abstract: Despite the architectural separation between intradomain and interdomain routing in the Internet, intradomain protocols do influence the path-selection process in the Border Gateway Protocol (BGP). When choosing between multiple equally-good BGP routes, a router selects the one with the closest egress point, based on the intradomain path cost. Under such hot-potato routing, an intradomain event can trigger BGP routing changes. To characterize the influence of hot-potato routing, we conduct controlled experiments with a commercial router. Then, we propose a technique for associating BGP routing changes with events visible in the intradomain protocol, and apply our algorithm to AT&T's backbone network. We show that (i) hot-potato routing can be a significant source of BGP updates, (ii) BGP updates can lag 60 seconds or more behind the intradomain event, (iii) the number of BGP path changes triggered by hot-potato routing has a nearly uniform distribution across destination prefixes, and (iv) the fraction of BGP messages triggered by intradomain changes varies significantly across time and router locations. We show that hot-potato routing changes lead to longer delays in forwarding-plane convergence, shifts in the flow of traffic to neighboring domains, extra externally-visible BGP update messages, and inaccuracies in Internet performance measurements.

Independent zone routing: an adaptive hybrid routing framework for ad hoc wireless networks

Abstract: To effectively support communication in such a dynamic networking environment as the ad hoc networks, the routing framework has to be adaptable to the spatial and temporal changes in the characteristics of the network, such as traffic and mobility patterns. Multiscoping, as is provided through the concept of the Zone Routing Protocol (ZRP) for example, can serve as a basis for such an adaptive behavior. The Zone Routing framework implements hybrid routing by every network node proactively maintaining routing information about its local neighborhood called the routing zone, while reactively acquiring routes to destinations beyond the routing zone. In this paper, we propose the Independent Zone Routing (IZR) framework, an enhancement of the Zone Routing framework, which allows adaptive and distributed configuration for the optimal size of each node's routing zone, on the per-node basis. We demonstrate that the performance of IZR is significantly improved by its ability to automatically and dynamically tune the network routing operation, so as to flexibly and robustly support changes in the network characteristics and operational conditions. As a point of reference, through this form of adaptation, we show that the volume of routing control traffic overhead in the network can be reduced by an order of magnitude, under some set of parameter values. Furthermore, the adaptive nature of IZR enhances the scalability of these networks as well.

Method and apparatus for routing and forwarding between virtual routers within a single network element

Abstract: A method and apparatus for routing and forwarding between virtual routers is described. A method in a single network element comprises peering a first virtual router to a second virtual router, wherein the first and second virtual routers have separate address spaces and separate routing tables, distributing a set of one or more routes from the first virtual router to the second virtual router, wherein a first of the set of routes identifies the first virtual router as a next hop of the first route, said first route including a destination, and downloading to a set of one or more forwarding tables, the destination and the next hop.

Router and network connecting method

Abstract: Route information used for dynamic route control can be shared by an active router and a standby router even in normal operation. After route calculation is performed according to a routing protocol, the calculated route information can be shared, enabling efficient operation. Protocol engine sections (31a to 31d) communicate with routers (41, 42), calculate a route to be selected for the routing according to the corresponding protocol. When the route information is altered, a route sharing information transmitting section (33) transmits the route information to the standby router. The protocol engine section in each router acting as an active router communicates with the router (41, 42), calculates a route to be selected for the routing according to the corresponding protocol, and transmits the route information, if it is altered. A route sharing information receiving section (34) receives the route information.

Optimal local topology knowledge for energy efficient geographical routing in sensor networks

Abstract: Since sensor networks can be composed of a very large number of nodes, the developed protocols for these networks must be scalable. Moreover, these protocols must be designed to prolong the battery lifetime of the nodes. Typical existing routing techniques for ad hoc networks are known not to scale well. On the other hand, the so-called geographical routing algorithms are known to be scalable but their energy efficiency has never been extensively and comparatively studied. For this reason, a novel analytical framework is introduced. In a geographical routing algorithm, the packets are forwarded by a node to its neighbor based on their respective positions. The proposed framework allows to analyze the relationship between the energy efficiency of the routing tasks and the extension of the range of the topology knowledge for each node. The leading forwarding rules for geographical routing are compared in this framework, and the energy efficiency of each of them is studied. Moreover partial topology knowledge forwarding, a new forwarding scheme, is introduced. A wider topology knowledge can improve the energy efficiency of the routing tasks but can increase the cost of topology information due to signaling packets that each node must transmit and receive to acquire this information, especially in networks with high mobility. The problem of determining the optimal knowledge range for each node to make energy efficient geographical routing decisions is tackled by integer linear programming. It is demonstrated that the problem is intrinsically localized, i.e., a limited knowledge of the topology is sufficient to take energy efficient forwarding decisions, and that the proposed forwarding scheme outperforms the others in typical application scenarios. For online solution of the problem, a probe-based distributed protocol which allows each node to efficiently select its topology knowledge, is introduced and shown to converge to a near-optimal solution very fast

Routing design in operational networks: a look from the inside

Abstract: In any IP network, routing protocols provide the intelligence that takes a collection of physical links and transforms them into a network that enables packets to travel from one host to another. Though routing design is arguably the single most important design task for large IP networks, there has been very little systematic investigation into how routing protocols are actually used in production networks to implement the goals of network architects. We have developed a methodology for reverse engineering a coherent global view of a network's routing design from the static analysis of dumps of the local configuration state of each router. Starting with a set of 8,035 configuration files, we have applied this method to 31 production networks. In this paper we present a detailed examination of how routing protocols are used in operational networks. In particular, the results show the conventional model of "interior" and "exterior" gateway protocols is insufficient to describe the diverse set of mechanisms used by architects, and we provide examples of the more unusual designs and examine their trade-offs. We discuss the strengths and weaknesses of our methodology, and argue that it opens paths towards new understandings of network behavior and design.

Content-based routing

Abstract: Implementations are described and claimed herein for content-based routing of messages in an overlay network. According to an exemplary implementation, routing nodes receive messages and return routing policies to the sending node based at least in part on content of the message. The routing policies include instructions for redirecting similar messages to other nodes in the overlay network. The sending node determines which policies to apply to the message. The sending node may then iterate through the routing policies, modifying the address in the message according to instructions included in the routing policies so that the message is sent, e.g., directly to the intended destination. Accordingly, the sending node is able to bypass one or more intermediary nodes to reduce latency in the overlay network.

Method for programming a routing layout design through one via layer

Abstract: A method for programming a routing layout design through one via layer includes forming a plurality of metal traces on a first routing layer and a second routing layer, and positioning a plurality of vias within a via layer disposed between the first and second routing layers for connecting the metal traces on the first and second routing layers according to a first current route defined by a predetermined circuit layout design to connect a first node and a second node so as to establish a second current route equivalent to the first current route.

Methods and systems for monitoring network routing

Abstract: The disclosed methods and systems include collecting routing data from a plurality of network routers (108), and collecting data across routers (104a, 106a) and across time to obtain network data. The network data can be streamed to a user (114) in real-time and the user (114) can interactively query the data. In one embodiment, interactive routing analyses, drill-down, and forensics can be performed using a repository of Border Gateway Protocol (BGP) (112) update traffic. Alarms can be set to detect selected routing problems. In setting the alarms, the message data for each router (104, 106) can be processed in timestamp order. Current message data from each router (104, 106) can be compared with previous message data to determine a condition status. An alarm can be provided when the condition status meets a temporal correlation criterion and/or spatial correlation criterion.

Proactive vs reactive approaches to failure resilient routing

Abstract: Dealing with network failures effectively is a major operational challenge for Internet service providers. Commonly deployed link state routing protocols such as OSPF react to link failures through global (i.e., network-wide) link state advertisements and routing table recomputations, causing significant forwarding discontinuity after a failure. The drawback with these protocols is that they need to trade off routing stability and forwarding continuity. To improve failure resiliency without jeopardizing routing stability, we propose a proactive local rerouting based approach called failure insensitive routing (FIR). The proposed approach prepares for failures using interface-specific forwarding, and upon a failure, suppresses the link state advertisement and instead triggers local rerouting using a backwarding table. In this paper, we prove that when no more than one link failure notification is suppressed, FIR always finds a loop-free path to a destination if one such path exists. We also formally analyze routing stability and network availability under both proactive and reactive approaches, and show that FIR provides better stability and availability than OSPF.

Rbridges: transparent routing

Abstract: This work describes a method of interconnecting links that combines the advantages of bridging and routing. The basic design is a replacement for a transparent bridge and makes no assumption about higher layer protocols. It involves creating an infrastructure of switches (which we call Rbridges, for "routing bridges") in which packets are routed, although, as with bridges, layer 2 end code location is learned through receipt of data packets. It avoids the disadvantages of bridges, since packets within the infrastructure need not be confined to a spanning tree, and packets are protected with a hop count and not proliferated while in transit, so there is no need for any artificial startup delay on ports to avoid temporary loops. This allows IP nodes to travel within a multi-link campus without changing IP addresses. The paper introduces further optimizations for IP, such as avoiding hooding ARP messages through the infrastructure, and (for IP nodes), allowing Rbridges to avoid learning on data packets.

Selection of routing paths based upon path quality of a wireless mesh network

Abstract: The invention includes an apparatus and method for determining an optimal route based upon path quality of routes to an access node of a wireless mesh network. The method includes receiving routing packets at the access node through at least one wireless route. Each routing packet including route information that identifies the wireless route of the routing packet. A success ration of a number of successfully received routing packets versus a number of transmitted routing packets is determined over a time Tl, for each wireless route. The wireless route having a greatest success ration is first selected, as are other wireless routes that have success rations within a predetermined amount of greatest success ratio. Of the first selected routes, routing packets are at the access node through the first selected routes. Again, each routing packet including route information that identifies the wireless route of the routing packet.

On the fundamental tradeoffs between routing table size and network diameter in peer-to-peer networks

Abstract: We study a fundamental tradeoff issue in designing a distributed hash table (DHT) in peer-to-peer (P2P) networks: the size of the routing table versus the network diameter. Observing that existing DHT schemes have either 1) a routing table size and network diameter both of O(log/sub 2/n), or 2) a routing table of size d and network diameter of O(n/sup 1/d/), S. Ratnasamy et al. (2001) asked whether this represents the best asymptotic "state-efficiency" tradeoffs. We show that some straightforward routing algorithms achieve better asymptotic tradeoffs. However, such algorithms all cause severe congestion on certain network nodes, which is undesirable in a P2P network. We rigorously define the notion of "congestion" and conjecture that the above tradeoffs are asymptotically optimal for a congestion-free network. The answer to this conjecture is negative in the strict sense. However, it becomes positive if the routing algorithm is required to eliminate congestion in a "natural" way by being uniform. We also prove that the tradeoffs are asymptotically optimal for uniform algorithms. Furthermore, for uniform algorithms, we find that the routing table size of O(log/sub 2/n) is a magic threshold point that separates two different "state-efficiency" regions. Our third result is to study the exact (instead of asymptotic) optimal tradeoffs for uniform algorithms. We propose a new routing algorithm that reduces the routing table size and the network diameter of Chord both by 21.4% without introducing any other protocol overhead, based on a novel number-theory technique. Our final result is to present Ulysses, a congestion-free nonuniform algorithm that achieves a better asymptotic "state-efficiency" tradeoff than existing schemes in the probabilistic sense, even under dynamic node joins/leaves.

Compact routing on Internet-like graphs

Abstract: The Thorup-Zwick (TZ) compact routing scheme is the first generic stretch-3 routing scheme delivering a nearly optimal per-node memory upper bound. Using both direct analysis and simulation, we derive the stretch distribution of this routing scheme on Internet-like inter-domain topologies. By investigating the TZ scheme on random graphs with power-law node degree distributions, P/sub k//spl sime/k/sup -/spl gamma//, we find that the average TZ stretch is quite low and virtually independent of /spl gamma/. In particular, for the Internet inter-domain graph with /spl gamma//spl sime/2.1, the average TZ stretch is around 1.1, with up to 70% of all pairwise paths being stretch-1 (shortest possible). As the network grows, the average stretch slowly decreases. We find routing table sizes to be very small (around 50 records for 104-node networks), well below their theoretical upper bounds. Furthermore, we find that both the average shortest path length (i.e. distance) d~ and width of the distance distribution /spl sigma/ observed in the real Internet inter-AS graph have values that are very close to the minimums of the average stretch in the d~- and /spl sigma/ -directions. This leads us to the discovery of a unique critical point of the average TZ stretch as a function of d~ and /spl sigma/. The Internet's distance distribution is located in a close neighborhood of this point. This is remarkable given the fact that the Internet inter-domain topology has evolved without any direct attention paid to properties of the stretch distribution. It suggests the average stretch function may be an indirect indicator of the optimization criteria influencing the Internet's inter-domain topology evolution.

Methods and apparatuses for routing data in a personal area network

Abstract: The invention is a routing method for data in a personal area network. The personal area network includes a plurality of nodes. The method includes receiving a frame at a node, determining whether the node contains a routing table entry for the frame destination, and when the node contains a routing table entry, determining a route for the frame based on a first routing protocol. The method further includes, when the node does not contain a routing table entry for the frame destination, determining whether a route should be discovered for the frame destination, and when a route should not be discovered, determining a route for the frame based on a second routing protocol.

SPROUT: P2P routing with social networks

Abstract: In this paper, we investigate how existing social networks can benefit P2P data networks by leveraging the inherent trust associated with social links We present a trust model that lets us compare routing algorithms for P2P networks overlaying social networks.We propose SPROUT, a DHT routing algorithm that, by using social links, significantly increases the number of query results and reduces query delays.We discuss further optimization and design choices for both the model and the routing algorithm Finally, we evaluate our model versus regular DHT routing and Gnutella-like flooding.