Showing papers on "Routing protocol published in 1989"

A loop-free extended Bellman-Ford routing protocol without bouncing effect

Abstract: Distributed algorithms for shortest-path problems are important in the context of routing in computer communication networks. We present a protocol that maintains the shortest-path routes in a dynamic topology, that is, in an environment where links and nodes can fail and recover at arbitrary times. The novelty of this protocol is that it avoids the bouncing effect and the looping problem that occur in the previous approaches of the distributed implementation of Bellman-Ford algorithm. The bouncing effect refers to the very long duration for convergence when failures happen or weights increase, and the nonterminating exchanges of messages, or counting-to-infinity behavior, in disconnected components of the network resulting from failures. The looping problems cause data packets to circulate and, thus, waste bandwidth. These undesirable effects are avoided without any increase in the overall message complexity of previous approaches required in the connected part of the network. The time complexity is better than the distributed Bellman-Ford algorithm encountering failures. The key idea in the implementation is to maintain only loop-free paths, and search for the shortest path only from this set.

Border Gateway Protocol (BGP)

Abstract: This RFC, together with its companion RFC-1164, "Application of the Border Gateway Protocol in the Internet", specify an inter-autonomous system routing protocol for the Internet. [STANDARDS-TRACK]

High Performance Communications In Processor Networks

Abstract: In order to provide an arbitrary and fully dynamic connectivity in a network of processors, transport mechanisms must be implemented, which provide the propagation of data from processor to processor, based on addresses contained within a packet of data. Such data transport mechanisms must satisfy a number of requirements - deadlock and livelock freedom, good hot-spot performance, high throughput and low latency. This paper proposes a solution to these problems, which allows deadlock free, adaptive, high throughput packet routing to be implemented on networks of processors. Examples are given which illustrate the technique for 2-D array and toroidal networks. An implementation of this scheme on arrays of transputers is described. The scheme also serves as a basis for a very low latency routing strategy named the mad postman, a detailed implementation of which is described here as well.

Expanders might be practical: fast algorithms for routing around faults on multibutterflies

Abstract: Simple deterministic O(log N)-step algorithms for routing packets on a multibutterfly are described. The algorithms are shown to be robust against faults, even in the worst case, and to be efficient from a practical point of view. As a consequence, the multibutterfly is shown to be an excellent candidate for a high-bandwidth, low-diameter switching network underlying a distributed-memory machine. >

A distributed time-slot assignment protocol for mobile multi-hop broadcast packet radio networks

Abstract: A distributed time-slot-assignment protocol for a mobile multihop broadcast packet radio network, using time division multiple access channel access, virtual circuit switching, and minimum hop path routing is developed. The protocol eliminates the single-point failure mode of centralized network management and the delays of centralized processing. It is applicable to the user-to-user communications functions of such systems as the Army's Enhanced Position Location and Reporting System (EPLRS). The important functions of the distributed protocol, including time-slot assignment, virtual circuit setup, and network synthesis, are identified, and implementing algorithms are presented and analyzed. >

An adaptive hierarchical routing protocol

Abstract: An adaptive hierarchical routing protocol based on the extension of the new Arpanet scheme is proposed and its simulated performance is presented. The protocol can adapt to rapidly changing environments and works for arbitrarily large networks. A number of existing schemes as well as the proposed scheme are simulated under many different environments and clustering structures. The proposed protocol is found to be superior to the other protocols tested in many different types of network traffic and topological configurations. The results indicate that intercluster links must be reliable, because (1) the failure of these links can significantly degrade the routing performance, even though the protocol does not degrade as badly as the existing scheme and (2) hierarchical routing protocols usually prefer small clusters, which means that there will be many intercluster links. The tradeoff between two conflicting performance criteria, response speed and communication overhead, is shown. >

Sirpent: a high-performance internetworking approach

Abstract: A clear target for computer communication technology is to support a high-performance global internetwork. Current internetworking approaches use either concatenated virtual circuits, as in X.75, or a “universal” internetwork datagram, as in the DoD Internet IP protocol and the ISO connectionless network protocol (CLNP). Both approaches have significant disadvantages.This paper describes Sirpent™ (Source Internetwork Routing Protocol with Extended Network Transfer)1, a new approach to an internetwork architecture that makes source routing the basis for interconnection, rather than an option as in IP. Its benefits include simple switching with low per-packet processing and delay, support for accounting and congestion control, and scalability to a global internetwork. It also supports flexible, user-controlled routing such as required for security, policy-based routing and realtime applications. We also propose a specific internetwork protocol, called VIPER™2, as a realization of the Sirpent approach.

An optimal shortest-path routing policy for network computers with regular mesh-connected topologies

Abstract: A probabilistic routing policy, the Z/sup 2/ (zigzag) routing policy, is presented within the class of nonadaptive, shortest-path routing policies for regular mesh-connected topologies such as n-dimensional toroids and hypercubes. The focus of the research is routing in networks of computers in a distributed computing environment, where constituent subcomputers are organized in a mesh-connected topology and communication among individual computers takes places by some form of message exchange. The authors prove the optimality of this policy with respect to two criteria: (1) maximizing the probability of reaching the destination from a given source without delays at intermediate nodes; and (2) minimizing the expected lifetime of a message. >

Compact distributed data structures for adaptive routing

Abstract: In designing a routing scheme for a communication network it is desirable to use as short as possible paths for routing messages, 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 cost of a route computed by the scheme and that of a cheapest path connecting the same pair of vertices.This paper presents a family of adaptive routing schemes for general networks. The hierarchical schemes H Sk (for every fixed k ≥ 1) guarantee a stretch factor of O (k2 · 3k) and require storing at most O (knk log n) bits of routing information per vertex. The new important features, that make the schemes appropriate for adaptive use, are applicability to networks with arbitrary edge costs;name-independence, i.e., usage of original names;a balanced distribution of the memory;an efficient on-line distributed preprocessing.

Markovian network processes: congestion-dependent routing and processing

Abstract: A Markovian network process describes the movement of discrete units among a set of nodes that process the units. There is considerable knowledge of such networks, often called queueing networks, in which the nodes operate independently and the routes of the units are independent. The focus of this study, in contrast, is on networks with dependent nodes and routings. Examples of dependencies are parallel processing across several nodes, blocking of transitions because of capacity constraints on nodes, alternate routing of units to avoid congestion, and accelerating or decelerating the processing rate at a node depending on downstream congestion. We introduce a general network process representing the numbers of units at the nodes and derive its equilibrium distribution. This distribution takes the form of a product of functions of vectors in which the arguments of the functions satisfy an interchangeability property. This new type of distribution may apply to other multi-variate processes as well. A basic idea in our approach is a linking of certain micro-level balance properties of the network routing to the processing rates at the nodes. The link is via “ routing-balance partitions” of nodes that are inherent in any network. A byproduct of this approach is a general characterization of blocking of transitions without the restriction that the process is reversible, which had been a standard assumption. We also give necessary and sufficient conditions under which a unit moving in the network sees a time average for the unmoved units (called the MUSTA property). Finally, we discuss when certain flows between nodes in an open network are Poisson processes.

Robust design and planning of a worldwide intelligent network

Abstract: The authors describe the structure of the worldwide intelligent network (WIN), describe methods for its design and planning, investigate the adequacy of decentralized control for problem-free worldwide call completion, explore the feasibility of adaptive routing and control concepts, discuss network robustness/reliability objectives, and describe a strategy for achieving these objectives for all cooperating international carriers. Several decentralized adaptive routing policies that are particularly attractive in the WIN environment and network performance improvements that can be achieved with the introduction of flexible routing capabilities are characterized. It is shown by example that network integration coupled with flexible routing and bandwidth allocation for preferential treatment of new services provides an effective approach for robust and economical new service provisioning. >

A distributed routing algorithm for mobile radio networks

Abstract: The authors present a distributed routing protocol intended for use in networks where the rate of topological change is not so fast as to make 'flooding' the only possible routing method but not so slow as to make one of the existing protocols for a static topology applicable. The routing algorithm adapts asynchronously in a distributed fashion to arbitrary changes in topology in the absence of global topological knowledge. The protocol maintains a set of loop-free routes to each destination from any node that desires a route. The protocol's performance, measured in terms of end-to-end packet delay and throughput, is compared with that of pure flooding and an alternative algorithm that is well suited to the medium-rate topological change environment envisioned here. The results show that, when the rate of topological change becomes very high, flooding is preferable to the other alternatives. For lower rate of change, it appears that, when the effects of channel access are accounted for, the performance of the new algorithm is encouraging in that it has been generally superior to that of the alternative protocols. >

Security issues in policy routing

Abstract: Most routing protocols, including proposed policy routing protocols, focus on environments where detection of an attack after it has taken place is sufficient. The authors explore the design of policy routing mechanisms for sensitive environments where more aggressive preventative measures are mandated. In particular, they detail the design of four secure protocol versions that prevent abuse by cryptographic checks of data integrity. They analyze and compare these schemes in terms of their prepacket processing overhead. It is concluded that preventative security is feasible, although the overhead cost is quite high. Consequently, it is critical that prevention-based schemes coexist with detection-based schemes. >

Goals and functional requirements for inter-autonomous system routing

Abstract: This document describes the functional requirements for a routing protocol to be used between autonomous systems. This document is intended as a necessary precursor to the design of a new inter- autonomous system routing protocol and specifies requirements for the Internet applicable for use with the current DoD IP, the ISO IP, and future Internet Protocols. It is intended that these requirements will form the basis for the future development of a new inter-autonomous systems routing architecture and protocol. This memo does not specify a standard.

Internet routing

Abstract: Comprising an estimated 60,000 hosts, the DARPA Internet is the largest existing internet. This paper traces the routing information protocols used by Internet gateways to build routing tables that define the paths datagrams traverse as they travel between end systems. We articulate the weaknesses and limitations of the most commonly used routing protocols, including RIP, GGP, and HELLO and examine how the protocols interact with each other and with EGP. Finally, we trace the evolution of routing as the Internet has grown from a single backbone (ARPANET) to its present inclusion of the ARPANET, Milnet, and NSFnet cross-country networks.

Dynamic routing in the AT&T network-improved service quality at lower cost

Abstract: The introduction of dynamic nonhierarchical routing (DNHR) into the AT&T switched network was completed in 1987. It has resulted in a marked improvement in AT&T network connection availability while simultaneously reducing network costs. The concept of dynamic routing and its implementation in the network over a several-year period by a multiorganizational team with AT&T are described. Dynamic routing has dramatically improved network service and robustness, particularly in responding to abnormal traffic or failure conditions. DNHR performance, systems engineering and development, and operation are discussed. >

Datagram authentication in internet gateways: implications of fragmentation and dynamic routing

Abstract: The implications of fragmentation and dynamic routing for datagram authentication at the gateway level are discussed. Two protocols are presented that permit varying degrees of fragmentation and dynamic routing, while allowing the gateways to authenticate successive packets belonging to authorized connections. The first adapts to changing paths and fragmentation by keeping state information on a per-packet basis, while the second restricts fragmentation but incurs little state overhead. The two methods vary in implementation complexity, overhead, number of extra packets sent, and host modification requirements. They were designed with different network characteristics in mind, and, since they are not mutually exclusive, both can be incorporated and used depending on the nature of communication. >

Routing using a pyramid data structure

Abstract: A general-purpose routing algorithm is proposed. Ideas behind both the maze-running algorithm and the hierarchical routing algorithm are combined into a hybrid routing algorithm. The new algorithm demonstrates a speed compatible to a hierarchical router and produces routings with quality equivalent to that by a maze router. Hybrid routing is based on the maze-running method with a third search dimension added. The extra search space is built by recursively constructing a hierarchy of coarser grid meshes. A user-given parameter can turn this algorithm into a pure maze router, a pure hierarchical router, or a wide spectrum of hybrid routers with different speed/quality characteristics between the extremes. With this approach, it is possible to handle easily a routing of large size, such as those encountered in the sea-of-gate layout. >

Computer-aided algorithmic design in the vehicle routing domain

Abstract: This paper advocates computer-aided algorithmic design as a means to enhance the development of expertise in the vehicle routing domain. The authors present a computer system, called ALTO, that supports the development of routing algorithms for transportation vehicles. ALTO provides a general framework modelling generic problem-solving procedures for vehicle routing problems. Within this general framework, specific procedures can be created via an instantiation process controlled by the user. In this way, many different heuristic strategies can be quickly designed and tested on complex problems for which no efficient algorithms are currently known.

Autonomous routing scheme for large scale network based on neural processing

Abstract: The authors discuss an autonomous routing scheme (called Holonic Routing) for large-scale networks that uses the principle of neural networks. In this scheme each node computes the optimal route whenever it tries to transmit a packet; thus the network can always maintain a balanced load, providing maximum transmission capacity in response to changes in traffic and topology. Because the routing procedure is packet by packet, even if a failure occurs in transit the packet will automatically be routed to avoid failed parts. Thus, a reliable nonstop network can be easily constructed using this scheme. The scheme is especially suitable for multimedia networks where large capacity and high reliability are needed. >

A routing architecture for very large networks undergoing rapid reconfiguration

Abstract: A routing architecture is described for very large communications networks with greater than 10,000 routing nodes and 100,000 end nodes. This architecture, called the Traveler Architecture, is designed to be independent of network configuration and to be robust even under conditions of rapid reconfiguration. Traveler is an extension of the ISO routing protocols. The Traveler architecture is designed to work with traffic characteristic of existing large networks, such as the Internet. While Traveler does not require a particular routing algorithm, it is designed to work in conjunction with families of distributed routing algorithms. Because Traveler is based on the paradigm of a human traveler, it attempts to use non-deterministic and heuristic methods rather than purely algorithmic methods to determine high quality routes between two points. Traveler builds on the Landmark and Area routing architectures.

Routing in multiple domain networks

Abstract: The problem of management and control in a large and, for simplicity, homogeneous packet-switched network is investigated. In particular, routing is considered as an important function of network management. The network consists of several individually controlled domains interconnected via gateway links. Each domain is controlled by its own network control center, while the overall network performance is managed by the integrated network control center. Each center has only a portion of the information required for global routing. The impact of the reduced information available at each center on network performance is investigated. A general approach to designing a hierarchical algorithm for routing in multi-domain networks is presented. A heuristic procedure suitable for packet-switched networks is proposed. An example of the algorithm is shown. Its performance is compared against a lower bound to the network performance. >

Performance evaluation of adaptive traffic routing in a metropolitan network: a case study

Abstract: A performance analysis of adaptive traffic in the telephone network of Marseilles, France is presented. The authors give the main reasons for introducing flexible routing-especially, state-dependent routing-in modern telephone networks. They present the Marseilles network under study and briefly describe the routing algorithm and the network design method used. They consider a number of scenarios ranging from traffic overloads to network failures in order to evaluate the robustness and performance of the adaptively routed network. Simulations that emphasize the role of state-dependent routing in network efficiency are presented and analyzed. In some specific cases, the state-dependent routing is complemented with predictive control actions to limit low priority or overflow traffic. This results in an improved grade of service. It is concluded that adaptive traffic routing can cope with a large range of network conditions, such as traffic overloads and equipment failures. >

Packet routing on grids of processors

Abstract: The problem of packet routing on n1 × ... × n r mesh-connected arrays or grids of processors is studied. For two-dimensional grids a deterministic routing algorithm is given for n × n meshes where each processor has a buffer of size f(n)

An Algorithm for Joint Routing and Scheduling in Radio Networks

Abstract: The problem of evacuation in minimum time of a PRN is considered. We decompose the problem into a scheduling problem for one hop neighbor transmissions and a routing problem. We propose an iterative algorithm for the routing problem. Finally we view the routing problem as a sequence of maxflow problems.

Acknowledgment-based broadband switching architecture

Abstract: A simple architecture for broadband switching based on a multistage interconnection network without internal buffers is proposed. An acknowledgment-based mechanism to manage contention situations that arise in the routing network is provided. The proposed architecture can be used with different kinds of routing networks to obtain a compromise between performance and complexity. For this purpose, performance comparisons between some significant examples of routing networks are also presented.

Adaptive forwarding and routing in frequency-hop spread-spectrum packet radio networks with partial-band jamming

Abstract: The authors consider adaptive protocols for routing around localized partial-band jamming in a frequency-hop (FH) packet radio network. With such protocols, a radio is permitted to modify its normal routing procedures according to local information. A computer program has been developed to simulate an FH packet radio network with partial-band jamming and interference due to other FH and narrowband radios. The network uses time-slotted, receiver-directed, FH spread-spectrum signaling. Results on throughput are presented, and comparisons between different protocols are obtained for a static network topology with both static and mobile network jamming. The authors also introduce least-resistance routing, a routing algorithm that accounts for multiple-access interference, jamming, and other partial-band interference. >

Bounded delay routing for real-time communication in tactical radio networks

Abstract: To deal with the need for availability and real time response, military communication has employed protocols with deterministic service such as that found in SS/TDMA (spread-spectrum/time-division multiple-access) control of satellite links, or T1, T2, or T3 ground relay optic fibers. The author addresses the problem of providing network layer communication with deterministic service in multihop radio networks. First, he investigates the complexity of the problem of minimizing delay in routing algorithms, showing that its complexity is high. He then presents a simple, efficient, and fully distributed control policy for packet-switched networks that guarantees bounded time-delay packet switching for any static or mobile network topology and any loop-free routing protocol. The proposed control thus provides deterministic packet delivery service in multihop radio networks without the significant overhead associated with circuit switching. >