Measured capacity of an Ethernet: myths and reality

Distributed multimedia applications require p erformance guarantees from the underlying network subsystem. Ethernet has been the dominant local area network architecture in the last decade, and we believe that it will remain popular because of its cost-eectiveness and the availability of higherbandwidth Ethernets. We present the design, implementation and evaluation of a software-based timed-token protocol called RETHER that provides real-time performance guarantees to multimedia applications without requiring any modications to existing Ethernet hardware. RETHER features a hybrid mode of operation to reduce the performance impact on non-real-time network trac, a race-condition-free distributed admission control mechanism, and an ecient token-passing scheme that protects the network against token loss due to node failures or otherwise. To our knowledge, this is the rst software implementation of a real-time protocol over existing Ethernet hardware. Performance m e asurements from experiments on a 10 Mbps Ethernet indicate that up to 60% of the raw bandwidth can be r eserved without deteriorating the performance of non-real-time trac. Additional simulations for high bandwidth networks and faster workstation hardware indicate that the protocol allows reservation of a greater percentage of the available bandwidth.1 Introduction With the growing trend towards distributed multimedia applications, it has become essential for the underlying systems to provide resource guarantees. Applications such a s LAN-based teleconferencing and video-on-demand services require support for real-time data transport from the underlying network to support real-time video playback. LANbased real-time transport also plays a critical role in extending WAN-based teleconferencing systems to the end-user's display, which m a y be connected to the site's WAN interface with a local area network. With the large existing base of Ethernets, it is essential to support such applications on the Ethernet. Our work addresses the problem of providing bandwidth guarantees on an Ethernet-based network.

show abstract

“…Secondly, the Ethernet protocol is not \fair" [7]. We conducted the following experiment t o v erify this.…”

Section: Introductionmentioning

confidence: 99%

Design, implementation, and evaluation of a software-based real-time Ethernet protocol

VenkatramaniChitra¹,

ChiuehTzi-cker²

1995

SIGCOMM Comput. Commun. Rev.

View full text Add to dashboard Cite

show abstract

“…For example, utilization of wired local area networks is relatively high (97%) [28] while the utilization of wireless IEEE 802.11 networks is on low level [29].…”

Section: Bandwidth Measurementmentioning

confidence: 99%

Cross-layer congestion control in ad hoc wireless networks

Kliazovich

Granelli

2006

Ad Hoc Networks

View full text Add to dashboard Cite

The paper presents the problem of performance degradation of transport layer protocols due to congestion of wireless local area networks. Following the analysis of available solutions to this problem, a cross-layer congestion avoidance scheme (C 3 TCP) is presented, able to obtain higher performance by gathering capacity information such as bandwidth and delay at the link layer. The method requires the introduction of an additional module within the protocol stack of the mobile node, able to adjust the outgoing data stream based on capacity measurements. Moreover, a proposal to provide optional field support to existing IEEE 802.11 protocol, in order to support the presented congestion control solution as well as many other similar approaches, is presented. Achieved results underline good agreement with design considerations and high utilization of the available resources.

show abstract

“…These assumptions sometimes lead to contradictory results. For example, research has shown maximum achievable CSMA/CD utilization of 60% with one set of assumptions [30], while later work showed utilization up to 97% with large packet sizes [4].…”

Section: Introductionmentioning

confidence: 99%