An Effective Re-marking Scheme for Diffserv AF Service through Multiple Domains

Shoichi MOTOHISA  Hiroyuki FUKUOKA  Ken-ichi BABA  Shinji SHIMOJO  

IEICE TRANSACTIONS on Information and Systems   Vol.E87-D   No.12   pp.2569-2577
Publication Date: 2004/12/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on New Technologies and their Applications of the Internet)
Category: Protocols, Applications and Services
QoS,  Diffserv,  Assured Forwarding,  DSCP re-marking,  

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AF service class in Diffserv by realizes minimum bandwidth guarantee with the use of differentiated drop precedence property marked on each packet. In the context of a multiple domains environment, however, QoS of individual flow is not always preserved due to the re-marking behavior forced at the domain boundaries. Focusing on this point, this paper proposes new packet re-marking schemes that can improve the per-flow QoS of AF service traversing multiple domains. The basic concept of the schemes distinguishes packets re-marked to out-of-profile at the domain boundaries from those already marked as out-of-profile at the time of entering the network, and allows the re-marked packet to recover back to in-of-profile, thus regaining its rightful QoS within the networks. The performance of the proposed schemes is evaluated through simulation. The results on UDP flows show the effectiveness of the proposed schemes for reducing packet losses on the flow through multiple domains and preserving fairness between flows. Simulations on TCP flows show that the proposed schemes improve the throughput of the flows through multiple domains. The proposed scheme is especially effective on the transfer time of short TCP flows such as Web traffic, whose throughput is affected more seriously by a single packet loss due to its flow control mechanisms.