Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523680
H. Akhtar
This paper describes AT&T's efforts in the area of networking with specific reference to modeling and simulation for the design of enterprise networks especially with upcoming ATM/BISDN technologies. A brief review of the tools researched and evaluated by AT&T is conducted followed by a detailed simulation example using ATM in LAN/WAN design. This is followed by a discussion of how this experience could be utilized internationally in the developing nations with specific reference to the Middle-East. This paper is supplemented with a separate tutorial on simulation and modeling in general and simulation tool usage in particular using OPNET. This is one of the leading tools that is now being widely used along with other tools within different business units at AT&T to develop professional services including enterprise networking, telecom and LAN/WAN architecture studies, network management and network operations support systems.
{"title":"Enterprise networking, modeling and simulation: status and prospects for the Middle-East","authors":"H. Akhtar","doi":"10.1109/SCAC.1995.523680","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523680","url":null,"abstract":"This paper describes AT&T's efforts in the area of networking with specific reference to modeling and simulation for the design of enterprise networks especially with upcoming ATM/BISDN technologies. A brief review of the tools researched and evaluated by AT&T is conducted followed by a detailed simulation example using ATM in LAN/WAN design. This is followed by a discussion of how this experience could be utilized internationally in the developing nations with specific reference to the Middle-East. This paper is supplemented with a separate tutorial on simulation and modeling in general and simulation tool usage in particular using OPNET. This is one of the leading tools that is now being widely used along with other tools within different business units at AT&T to develop professional services including enterprise networking, telecom and LAN/WAN architecture studies, network management and network operations support systems.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"10 1","pages":"289-294"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76266511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523670
C. Kang, Byung-Seok Park, Ill-Keun Rhee
Much has been previously written about the performance of slotted ring networks. However, the results are not appropriate to apply for the new generation slotted rings, like counter-rotating multichannel slotted rings. In this paper, a novel technique for quantitative measurement of average transfer delay of a class of slotted rings is presented. The approach is expanded to compare the average transfer delay of various slotted rings including counter-rotating multichannel slotted ring networks. An extensive simulation study has been carried out to verify the derived analytical results. The analytical results show an excellent agreement with simulation results over a broad range of parameters. The average transfer delay of the counter-rotating slotted ring network is about half that of the conventional multichannel slotted rings. Spatial reuse using the counter-rotating channel configuration also increases the effective ring throughput significantly, compared to conventional simple multichannel ring networks. The results show that the major part of the cell transfer delay comes from the propagation delay from a source to a destination. It is also observed that the network throughput depends upon the aggregated transmission capacity of the network.
{"title":"Performance comparison of a class of slotted ring networks","authors":"C. Kang, Byung-Seok Park, Ill-Keun Rhee","doi":"10.1109/SCAC.1995.523670","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523670","url":null,"abstract":"Much has been previously written about the performance of slotted ring networks. However, the results are not appropriate to apply for the new generation slotted rings, like counter-rotating multichannel slotted rings. In this paper, a novel technique for quantitative measurement of average transfer delay of a class of slotted rings is presented. The approach is expanded to compare the average transfer delay of various slotted rings including counter-rotating multichannel slotted ring networks. An extensive simulation study has been carried out to verify the derived analytical results. The analytical results show an excellent agreement with simulation results over a broad range of parameters. The average transfer delay of the counter-rotating slotted ring network is about half that of the conventional multichannel slotted rings. Spatial reuse using the counter-rotating channel configuration also increases the effective ring throughput significantly, compared to conventional simple multichannel ring networks. The results show that the major part of the cell transfer delay comes from the propagation delay from a source to a destination. It is also observed that the network throughput depends upon the aggregated transmission capacity of the network.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"28 1","pages":"220-226"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76128174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523644
S. Dimolitsas, J. G. Phipps, M. Sherif
This paper provides information on a laboratory study conducted by COMSAT Laboratories to evaluate the effect of echo and delay on facsimile call retention rates. The term "call retention" is defined as the ability of a pair of facsimile terminals to maintain a circuit connection until all pages have been successfully transmitted after negotiation of the high speed signaling rate. The results of this study indicate that the effect of network echo has the potential of degrading facsimile call retention. In addition, propagation delay reduces retention rates even further. The results of this work are currently under consideration by the International Telecommunication Union (formerly CCITT) in the formulation of test methodologies for assessing facsimile terminal implementation performance.
{"title":"Impact of network transmission delay and echo on Group 3 facsimile performance","authors":"S. Dimolitsas, J. G. Phipps, M. Sherif","doi":"10.1109/SCAC.1995.523644","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523644","url":null,"abstract":"This paper provides information on a laboratory study conducted by COMSAT Laboratories to evaluate the effect of echo and delay on facsimile call retention rates. The term \"call retention\" is defined as the ability of a pair of facsimile terminals to maintain a circuit connection until all pages have been successfully transmitted after negotiation of the high speed signaling rate. The results of this study indicate that the effect of network echo has the potential of degrading facsimile call retention. In addition, propagation delay reduces retention rates even further. The results of this work are currently under consideration by the International Telecommunication Union (formerly CCITT) in the formulation of test methodologies for assessing facsimile terminal implementation performance.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"283 1","pages":"37-41"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74379154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523675
C. Perkins, Tangirala Jagannadh
Mobile-IP and the Dynamic Host Configuration Protocol (DHCP) are two protocols which are likely to be implemented together for use with wireless computers. We explore the ways that they can be used with in mobile computers. These protocols interact in subtle ways, presenting a system architect with a variety of trade-offs that need careful analysis. We detail the important interactions and system design issues, and also explain the design and implementation of a new DHCP option for mobile computers. The difference between mobility and portability is explained; this paper only emphasizes approaches for mobility. We explore implementation issues that we have encountered.
{"title":"DHCP for mobile networking with TCP/IP","authors":"C. Perkins, Tangirala Jagannadh","doi":"10.1109/SCAC.1995.523675","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523675","url":null,"abstract":"Mobile-IP and the Dynamic Host Configuration Protocol (DHCP) are two protocols which are likely to be implemented together for use with wireless computers. We explore the ways that they can be used with in mobile computers. These protocols interact in subtle ways, presenting a system architect with a variety of trade-offs that need careful analysis. We detail the important interactions and system design issues, and also explain the design and implementation of a new DHCP option for mobile computers. The difference between mobility and portability is explained; this paper only emphasizes approaches for mobility. We explore implementation issues that we have encountered.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"8 1","pages":"255-261"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79635305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523661
W. D. Maughan, Amy B. Reiss, Mark Schertler
History tells us that Julius Cesar shifted each letter in his messages to his generals by three places in the alphabet. The generals knew to shift back by three letters to read the message. Securing information for transfer between entities requires an agreement on how the information will be protected. Modern science and technology has brought more advanced methods of protecting information, but the basic need for an agreement between entities desiring to communicate securely still exists. In modern terms this agreement is a security association (SA). There are varying definitions of a security association in current standards and this paper attempts to clarify, these definitions. Security protocols requiring security associations as well as emerging protocols that establish and manage security associations are presented. If future global interoperability is to be provided securely one of the first building blocks will be the ability to negotiate and establish security associations. Therefore, issues that must be resolved for future global interoperability are discussed. Our work to create a network security research environment for future global needs is also presented.
{"title":"Security associations: building blocks for secure communications","authors":"W. D. Maughan, Amy B. Reiss, Mark Schertler","doi":"10.1109/SCAC.1995.523661","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523661","url":null,"abstract":"History tells us that Julius Cesar shifted each letter in his messages to his generals by three places in the alphabet. The generals knew to shift back by three letters to read the message. Securing information for transfer between entities requires an agreement on how the information will be protected. Modern science and technology has brought more advanced methods of protecting information, but the basic need for an agreement between entities desiring to communicate securely still exists. In modern terms this agreement is a security association (SA). There are varying definitions of a security association in current standards and this paper attempts to clarify, these definitions. Security protocols requiring security associations as well as emerging protocols that establish and manage security associations are presented. If future global interoperability is to be provided securely one of the first building blocks will be the ability to negotiate and establish security associations. Therefore, issues that must be resolved for future global interoperability are discussed. Our work to create a network security research environment for future global needs is also presented.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"30 1","pages":"157-163"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83309477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523681
M. Sherif, A. Crossman
There have been significant advances in the design and development of "toll-quality" packetization systems. The paper presents various issues that affect the packetization of speech such as robustness to noise, reconstitution of the flow of speech and congestion control. The target audience consists of designers and implementers of speech packetization systems as well as service providers concerned with the quality of service and efficiency of transmission.
{"title":"Overview of speech packetization","authors":"M. Sherif, A. Crossman","doi":"10.1109/SCAC.1995.523681","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523681","url":null,"abstract":"There have been significant advances in the design and development of \"toll-quality\" packetization systems. The paper presents various issues that affect the packetization of speech such as robustness to noise, reconstitution of the flow of speech and congestion control. The target audience consists of designers and implementers of speech packetization systems as well as service providers concerned with the quality of service and efficiency of transmission.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"515 1","pages":"296-304"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77087754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523657
S. Shaikh
Diversity has been widely recognized as a critical factor for robustness in networks. In order to resist isolations due to link and node failures, we need to route along paths which are both span-disjoint (physically disjoint) and node-disjoint. In this way we can design the network for fault tolerance or graceful degradation. We demonstrate the procedure to obtain span-disjoint paths. This procedure may be applied to an arbitrary network topology, without restrictions on the span sharing configurations. In those cases where two completely disjoint paths do not exist, the procedure still tries to find a pair of paths which are as diverse as possible. The solution path pair we obtain is not guaranteed to be optimal, but gives us an optimal or near-optimal design, relatively quickly. The algorithm also accepts parameters which can be used to specify the cost-robustness tradeoffs.
{"title":"Span-disjoint paths for physical diversity in networks","authors":"S. Shaikh","doi":"10.1109/SCAC.1995.523657","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523657","url":null,"abstract":"Diversity has been widely recognized as a critical factor for robustness in networks. In order to resist isolations due to link and node failures, we need to route along paths which are both span-disjoint (physically disjoint) and node-disjoint. In this way we can design the network for fault tolerance or graceful degradation. We demonstrate the procedure to obtain span-disjoint paths. This procedure may be applied to an arbitrary network topology, without restrictions on the span sharing configurations. In those cases where two completely disjoint paths do not exist, the procedure still tries to find a pair of paths which are as diverse as possible. The solution path pair we obtain is not guaranteed to be optimal, but gives us an optimal or near-optimal design, relatively quickly. The algorithm also accepts parameters which can be used to specify the cost-robustness tradeoffs.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"30 1","pages":"127-133"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88868248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523665
Carlos Hirsch Ganievich
We present a dynamic econometric model of the Mexican Telephone Company (Telmex). This model is used to compare different management strategies (state-owned monopoly, unregulated monopoly, regulated monopoly and competition) to find out the essential parameters that are pressing Latin American countries to restructure the telecom sector and to finally open it to competition. Simulating 16 years of behavior in various scenarios we show that long distance rates are the main reason forcing these fundamental changes.
{"title":"Economics behind Latin American telecom privatizations?","authors":"Carlos Hirsch Ganievich","doi":"10.1109/SCAC.1995.523665","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523665","url":null,"abstract":"We present a dynamic econometric model of the Mexican Telephone Company (Telmex). This model is used to compare different management strategies (state-owned monopoly, unregulated monopoly, regulated monopoly and competition) to find out the essential parameters that are pressing Latin American countries to restructure the telecom sector and to finally open it to competition. Simulating 16 years of behavior in various scenarios we show that long distance rates are the main reason forcing these fundamental changes.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"4 1","pages":"189-195"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76787577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523674
S. El-Khamy, A. Ali, H. Elragal
The blind equalization of data distorted in dispersive channels with considerable ISI is investigated. The blind channel estimation is realized without using training sequences. Two methods based on the higher order spectra and polycepstra are considered. The estimated channel response is used to adaptively equalize the distorted data. The speed of convergence of the adaptive equalizer is highly increased by suitable filtration of the estimated channel impulse response before adaptive equalization. This is done by providing smart initial weights for the adaptive equalizer through inverse filtering or matched filtering of the estimated channel response. The addition of a deconvolving filter to the matched filter is suggested to cancel the effects of the high offset correlation values of the channel impulse response that is characteristic of channels with severe ISI.
{"title":"Fast blind equalization using higher-order-spectra channel-estimation in the presence of severe ISI","authors":"S. El-Khamy, A. Ali, H. Elragal","doi":"10.1109/SCAC.1995.523674","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523674","url":null,"abstract":"The blind equalization of data distorted in dispersive channels with considerable ISI is investigated. The blind channel estimation is realized without using training sequences. Two methods based on the higher order spectra and polycepstra are considered. The estimated channel response is used to adaptively equalize the distorted data. The speed of convergence of the adaptive equalizer is highly increased by suitable filtration of the estimated channel impulse response before adaptive equalization. This is done by providing smart initial weights for the adaptive equalizer through inverse filtering or matched filtering of the estimated channel response. The addition of a deconvolving filter to the matched filter is suggested to cancel the effects of the high offset correlation values of the channel impulse response that is characteristic of channels with severe ISI.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"6 4 1","pages":"248-254"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82908822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-27DOI: 10.1109/SCAC.1995.523696
Ka-Cheong Leung, M. Hamdi
The performance of distributed supercomputing computing environments are mainly dependent on three factors: distributed programming tools, computing nodes, and LANs employed. In this paper, we analyze the performance of all these factors experimentally and analytically. The distributed programming tools that we employed are PVM and Express. The computing nodes that we employed are SUN and HP workstations, and the LANs that we considered are an Ethernet and FDDI networks. Extensive timing experiments, including one-to-one communications, exchange operations, and broadcast operations, have been performed and analyzed. Moreover, analytic models have been developed to analyze the behavior of the network protocols employed by the LAN-based platforms as well as to estimate the communication overhead for the computing software tools.
{"title":"Assessment of network protocols and software tools for distributed computing","authors":"Ka-Cheong Leung, M. Hamdi","doi":"10.1109/SCAC.1995.523696","DOIUrl":"https://doi.org/10.1109/SCAC.1995.523696","url":null,"abstract":"The performance of distributed supercomputing computing environments are mainly dependent on three factors: distributed programming tools, computing nodes, and LANs employed. In this paper, we analyze the performance of all these factors experimentally and analytically. The distributed programming tools that we employed are PVM and Express. The computing nodes that we employed are SUN and HP workstations, and the LANs that we considered are an Ethernet and FDDI networks. Extensive timing experiments, including one-to-one communications, exchange operations, and broadcast operations, have been performed and analyzed. Moreover, analytic models have been developed to analyze the behavior of the network protocols employed by the LAN-based platforms as well as to estimate the communication overhead for the computing software tools.","PeriodicalId":90699,"journal":{"name":"Proceedings. IEEE Symposium on Computers and Communications","volume":"191 1","pages":"414-420"},"PeriodicalIF":0.0,"publicationDate":"1995-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75831281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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