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Proceedings Paper

Implementation of NAT for VoIP based on H.323 protocol
Author(s): Yong-feng Huang; Shi-ming Xu; Xing Li
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Paper Abstract

In this paper, firstly, we introduce the protocol of VoIP, and analyze the process of a call establishment based on H.323, including RAS, H.225, and H.245 phases. Then, we focus on implementing ALG, which allow an application on a host in one address realm to connect to its counterpart running on a host in different realm transparently. An ALG may interact with NAT to set up state, use NAT state information, modify application specific payload and perform whatever else necessary to get the application running across disparate address realm. In addition, this section presents many important data structures and algorithms, for example, the algorithm to check for match of remote IP address and port, the algorithm for classifier to look at both outbound as well as an inbound packets, and etc. Finally, the paper describes and analyzes the results of experiments, and we obtain some significant parameters, namely, call setup latency and packet forwarding latency. The experiments and applications demonstrate it feasible for ALG to realize NAT for VoIP.

Paper Details

Date Published: 15 April 2004
PDF: 7 pages
Proc. SPIE 5282, Network Architectures, Management, and Applications, (15 April 2004); doi: 10.1117/12.519418
Show Author Affiliations
Yong-feng Huang, Tsinghua Univ. (China)
Shi-ming Xu, Tsinghua Univ. (China)
Xing Li, Tsinghua Univ. (China)

Published in SPIE Proceedings Vol. 5282:
Network Architectures, Management, and Applications
S. J. Ben Yoo; Kwok-wai Cheung; Yun-Chur Chung; Guangcheng Li, Editor(s)

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