This paper presents ongoing work in the field of the IEEE 802.3x flow control scheme within a full-duplex Ethernet LAN. Our simulation-based investigations compare the throughput of TCP streams in selected network topologies when either the Ethernet flow control is disabled or enabled. In general, Ethernet's hop-by-hop flow control leads to good performance of TCP in homogenous networks where all clients are connected to a congested switch with the same link speed. However, as soon as a network consists of clients connected with slow (e.g. 10 Mb/s) and fast (e.g. 100 Mb/s) links to the switch, the effect known as 'head of line blocking' shows up as congestion occurs and flow control is triggered. As a result of this, the throughput of data streams destined to slow clients increases because packets are no longer discarded but the throughput of streams destined to fast clients is reduced considerably.
{"title":"On the effects of the IEEE 802.3x flow control in full-duplex Ethernet LANs","authors":"Oliver Feuser, A. Wenzel","doi":"10.1109/LCN.1999.802012","DOIUrl":"https://doi.org/10.1109/LCN.1999.802012","url":null,"abstract":"This paper presents ongoing work in the field of the IEEE 802.3x flow control scheme within a full-duplex Ethernet LAN. Our simulation-based investigations compare the throughput of TCP streams in selected network topologies when either the Ethernet flow control is disabled or enabled. In general, Ethernet's hop-by-hop flow control leads to good performance of TCP in homogenous networks where all clients are connected to a congested switch with the same link speed. However, as soon as a network consists of clients connected with slow (e.g. 10 Mb/s) and fast (e.g. 100 Mb/s) links to the switch, the effect known as 'head of line blocking' shows up as congestion occurs and flow control is triggered. As a result of this, the throughput of data streams destined to slow clients increases because packets are no longer discarded but the throughput of streams destined to fast clients is reduced considerably.","PeriodicalId":265611,"journal":{"name":"Proceedings 24th Conference on Local Computer Networks. LCN'99","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126226754","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}
Markus Albrecht, M. Frank, P. Martini, Markus Schetelig, Asko Vilavaara, A. Wenzel
We present protocol concepts for an extension of IP for mobility issues in Bluetooth networks. The protocol is called BLUEPAC IP, where BLUEPAC stands for "BLUEtooth Public ACcess". "Public access" means access to various kinds of information in public areas, e.g. airplane, train, hotel room, department store, museum. Bluetooth will reside in low-cost chips that provide wireless communication up to OSI Layer 2. By the end of this year many mobile devices, e.g. notebooks, PDAs, cell phones, will contain Bluetooth chips as a cable replacement. But Bluetooth is move powerful: with a suitable network protocol that inherits all aspects of IP, it will be possible to provide IP services over Bluetooth. BLUEPAC IP takes IP as a basis and additionally includes functionalities of mobile IP and cellular IP for local IP address assignment, routing issues and handoff support.
{"title":"IP services over Bluetooth: leading the way to a new mobility","authors":"Markus Albrecht, M. Frank, P. Martini, Markus Schetelig, Asko Vilavaara, A. Wenzel","doi":"10.1109/LCN.1999.801990","DOIUrl":"https://doi.org/10.1109/LCN.1999.801990","url":null,"abstract":"We present protocol concepts for an extension of IP for mobility issues in Bluetooth networks. The protocol is called BLUEPAC IP, where BLUEPAC stands for \"BLUEtooth Public ACcess\". \"Public access\" means access to various kinds of information in public areas, e.g. airplane, train, hotel room, department store, museum. Bluetooth will reside in low-cost chips that provide wireless communication up to OSI Layer 2. By the end of this year many mobile devices, e.g. notebooks, PDAs, cell phones, will contain Bluetooth chips as a cable replacement. But Bluetooth is move powerful: with a suitable network protocol that inherits all aspects of IP, it will be possible to provide IP services over Bluetooth. BLUEPAC IP takes IP as a basis and additionally includes functionalities of mobile IP and cellular IP for local IP address assignment, routing issues and handoff support.","PeriodicalId":265611,"journal":{"name":"Proceedings 24th Conference on Local Computer Networks. LCN'99","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131405394","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}
The practical network performances of two commercial IEEE 802.11 compliant wireless local area networks (WLANs) are measured at the medium access control sublayer. A number of tests conducted on the WLANs yielded important characteristics such as throughput and response time under various network loads. The results reveal that the buffering and fragmentation of data frames can seriously influence the performance of an IEEE 802.11 WLAN. Although the length of a data frame and the bit rate of the wireless transceiver also affect the WLANs transmission capabilities, its performance is generally unaffected by the type of frame addressing and the use of reservation frames such as request-to-send (RTS) and clear-to-send (CTS). These observations have not been reported in the analytical, simulation or measurement studies carried out so far. Thus, the detailed empirical results presented in this paper will be useful for administrators of IEEE 802.11 WLAN systems.
{"title":"Measured performance of the IEEE 802.11 wireless LAN","authors":"B. Bing","doi":"10.1109/LCN.1999.801993","DOIUrl":"https://doi.org/10.1109/LCN.1999.801993","url":null,"abstract":"The practical network performances of two commercial IEEE 802.11 compliant wireless local area networks (WLANs) are measured at the medium access control sublayer. A number of tests conducted on the WLANs yielded important characteristics such as throughput and response time under various network loads. The results reveal that the buffering and fragmentation of data frames can seriously influence the performance of an IEEE 802.11 WLAN. Although the length of a data frame and the bit rate of the wireless transceiver also affect the WLANs transmission capabilities, its performance is generally unaffected by the type of frame addressing and the use of reservation frames such as request-to-send (RTS) and clear-to-send (CTS). These observations have not been reported in the analytical, simulation or measurement studies carried out so far. Thus, the detailed empirical results presented in this paper will be useful for administrators of IEEE 802.11 WLAN systems.","PeriodicalId":265611,"journal":{"name":"Proceedings 24th Conference on Local Computer Networks. LCN'99","volume":"09 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124643173","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}
In a typical real-time voice application, voice packets are produced at deterministically-spaced time intervals. In the network they encounter a variable amount of delay that changes the deterministic time intervals. A receiving host can employ a buffer to delay the playout of the voice packets in order to reconstruct the original timing. Adaptive techniques can perform continuous estimations of the network delays and dynamically adjust the buffering delay at the beginning of each talkspurt. Such adjustments are usually undetectable by the human listener. This research develops a new, adaptive "gap-based" algorithm that can be tuned for both end-to-end delay and packet loss to satisfy a user-desired tolerance. This new gap based algorithm adapts the buffering delay based on historical information of arrival and playout times of received voice packers in the previous talkspurt. A simulation study shows that the new gap based algorithm can reduce delay by 10% when compared with existing methods.
{"title":"An algorithm for playout of packet voice based on adaptive adjustment of talkspurt silence periods","authors":"Jesus Pinto, Kenneth J. Christensen","doi":"10.1109/LCN.1999.802033","DOIUrl":"https://doi.org/10.1109/LCN.1999.802033","url":null,"abstract":"In a typical real-time voice application, voice packets are produced at deterministically-spaced time intervals. In the network they encounter a variable amount of delay that changes the deterministic time intervals. A receiving host can employ a buffer to delay the playout of the voice packets in order to reconstruct the original timing. Adaptive techniques can perform continuous estimations of the network delays and dynamically adjust the buffering delay at the beginning of each talkspurt. Such adjustments are usually undetectable by the human listener. This research develops a new, adaptive \"gap-based\" algorithm that can be tuned for both end-to-end delay and packet loss to satisfy a user-desired tolerance. This new gap based algorithm adapts the buffering delay based on historical information of arrival and playout times of received voice packers in the previous talkspurt. A simulation study shows that the new gap based algorithm can reduce delay by 10% when compared with existing methods.","PeriodicalId":265611,"journal":{"name":"Proceedings 24th Conference on Local Computer Networks. LCN'99","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127825510","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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