Congestion window-based adaptive burst assembly for TCP traffic in OBS networks
Author
Ozsarac, S.
Karasan, E.
Date
2010-06-29Source Title
Photonic Network Communications
Print ISSN
1387-974X
Publisher
Springer
Volume
20
Issue
2
Pages
138 - 150
Language
English
Type
ArticleItem Usage Stats
107
views
views
87
downloads
downloads
Abstract
Burst assembly is one of the key factors affecting the TCP performance in optical burst switching (OBS) networks. When the TCP congestion window is small, the fixed-delay burst assembler waits unnecessarily long, which increases the end-to-end delay and thus decreases the TCP goodput. On the other hand, when the TCP congestion window becomes larger, the fixed-delay burst assembler may unnecessarily generate a large number of small-sized bursts, which increases the overhead and decreases the correlation gain, resulting in a reduction in the TCP goodput. In this paper, we propose adaptive burst assembly algorithms that use the congestion window sizes of TCP flows. Using simulations, we show that the usage of the congestion window size in the burst assembly algorithm significantly improves the TCP goodput (by up to 38.4% on the average and by up to 173.89% for individual flows) compared with the timerbased assembly, even when the timer-based assembler uses the optimum assembly period. It is shown through simulations that even when estimated values of the congestion window size, that are obtained via passive measurements, are used, TCP goodput improvements are still close to the results obtained by using exact values of the congestion window.
Keywords
Adaptive burst assemblyTCP over OBS
Burst assembly
Congestion window
End to end delay
Fixed-delay
Key factors
OBS networks
Passive measurements
TCP congestion
TCP flows
Optical switches
Optical burst switching