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Access Protocol (access + protocol)

Distribution by Scientific Domains

Information Science and Computing	33%

Selected Abstracts

Cross-domain authorization for federated virtual organizations using the myVocs collaboration environment

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 4 2009
Jill Gemmill
Abstract This paper describes our experiences building and working with the reference implementation of myVocs (my Virtual Organization Collaboration System). myVocs provides a flexible environment for exploring new approaches to security, application development, and access control built from Internet services without a central identity repository. The myVocs framework enables virtual organization (VO) self-management across unrelated security domains for multiple, unrelated VOs. By leveraging the emerging distributed identity management infrastructure. myVocs provides an accessible, secure collaborative environment using standards for federated identity management and open-source software developed through the National Science Foundation Middleware Initiative. The Shibboleth software, an early implementation of the Organization for the Advancement of Structured Information Standards Security Assertion Markup Language standard for browser single sign-on, provides the middleware needed to assert identity and attributes across domains so that access control decisions can be determined at each resource based on local policy. The eduPerson object class for lightweight directory access protocol (LDAP) provides standardized naming, format, and semantics for a global identifier. We have found that a Shibboleth deployment supporting VOs requires the addition of a new VO service component allowing VOs to manage their own membership and control access to their distributed resources. The myVocs system can be integrated with Grid authentication and authorization using GridShib. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Performance evaluation of GPON vs EPON for multi-service access

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2009
T. Orphanoudakis
Abstract Recently both ITU and IEEE have standardized solutions for passive optical networks (PONs) operating at gigabit per second line rates and optimized for the transport of packet-based traffic to improve the efficiency of previously standardized broadband PONs, which used the ATM cell as the data transport unit. The efficiency and performance of PON systems depend on the transmission convergence layer and mainly on the implemented medium access protocol. Although the latter is not part of the standards and left to the implementer, the standards describe a set of control fields that constitute the tool-set for the media access control (MAC) operation. Though starting from a common and quite obvious basis, the two standards present significant differences with the legacy of Ethernet marking the IEEE approach, while the emphasis of ITU is on demanding services. In this paper we compare the efficiency and performance of the two systems assuming the implementation of as close as possible MAC protocols. The target is twofold: assess and compare the traffic handling potential of each of the two standards and identify the range of applications they can support. Useful insight can also be gained to the MAC tools that could be designed into the next generation extra large WDM PONs. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Hybrid prioritized multiple access protocols for bank LANs

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2004
M. Sklira
Abstract Bank communication networks support four classes of traffic: Alarm, BSC, SNA and IP traffic, with each class of traffic having different priority requirements. In this paper, a framework for the design of multiple access protocols which are capable of handling the above priority classes is introduced. Furthermore, a hybrid multiple access protocol that has been designed according to the proposed framework is presented and evaluated by means of extensive simulation results. The proposed protocol, is applicable to a broad range of prioritized LANs. Copyright © 2004 John Wiley & Sons, Ltd. [source]

A multiple access protocol with explicit and implicit reservation

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2001
F. Davoli
Abstract A new version of a MAC-level protocol is introduced and investigated, operating in a cellular environment, where a base station co-ordinates mobile users within each cell. The channel multiplexing structure is based on time division, and the slots in each frame are dynamically assigned to the users and their service classes by the cell base station. Decisions are taken on the basis of binary channel feedback information (collision/no collision), by assuming independence in the presence of packets at the mobile stations, and aim at maximizing the one-step throughput in the current frame. The frame is divided into two periods: the first (short) one contains a number of minislots, equal to the number of ,real' slots (i.e. those capable of containing a fixed size packet) of the second part. At the beginning of the frame, the access rights are computed and broadcast to the users; the enabled stations that have a packet to transmit respond, by sending a short burst that contains their ID in a minislot. This most recent feedback is used at the base station to update the parameters of the decision algorithm, which is then re-applied to yield the final access rights for the second part of the frame. The performance of the scheme is analysed by simulation in the presence of mixed voice and data traffic, and compared with those of a reservation random access protocol using the same algorithm in a single-phase fashion (RRA-ISA) and PRMA. Copyright © 2001 John Wiley & Sons, Ltd. [source]

ARCMA,adaptive request channel multiple access protocol for wireless ATM networks

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2001
Professor Anna Ha
We propose a new multiple access protocol based on demand assignment. This protocol is designed to reduce contention in the request phase while minimizing transmission delay under various network (ATM) environments. Our protocol uses an adaptive scheme that changes under heavy traffic conditions, and also provides priority to certain delay-sensitive traffic. Copyright © 2001 John Wiley & Sons, Ltd. [source]