以SIP為基礎之IPv4/IPv6網路電話轉換器之研發

Abstract

隨著SIP（Session Initiation Protocol）網路電話的普及，每個網路電話裝置都至少需要一個IP（Internet Protocol）位址，IPv4（IP version 4）將不足以分配給每一台網路電話。雖然IPv6（IP version 6）提供大量的IP位址來解決IPv4位址不足的問題，但在IPv6佈建初期大多數的SIP網路電話仍只支援IPv4。本論文提出SIPv6 Translator系統之設計與實作，提供一個SIP協定的轉換機制，讓IPv6網路電話使用者與IPv4網路電話使用者可以互相通訊。SIPv6 Translator系統以NAT-PT（Network Address Translation and Protocol Translation）機制為基礎，加入了SIP-ALG（Application Level Gateway）轉換機制，針對SIP訊息內的IP資訊作轉換，讓SIP訊息可以在IPv6與IPv4網路SIP設備之間正確的傳遞。本論文針對SIPv6 Translator系統作了互通性測試與效能評估，得知本系統對於通話建立所造成的影響非常小，幾乎可以忽略。此成果對於IPv6與VoIP（Voice over IP）的推廣均有相當大的助益。

Session Initiation Protocol（SIP）-based Voice over IP（VoIP） services have become popular recently. Since each SIP phone needs at least one Internet Protocol（IP） address, shortage of IP version 4（IPv4） address resource becomes a problem. IP version 6 （IPv6）provides a large address space for solving this problem, but most SIP phones support only IPv4 in the early deployment of IPv6. This thesis proposes design and implementation of SIPv6 Translator, which provides a transition mechanism for SIP between IPv6 and IPv4 users. SIPv6 Translator, which includes Network Address Translation and Protocol Translation（NAT-PT）and SIP-Application Level Gateway（ALG） mechanisms, translates IP information embedded in SIP messages, so that SIP messages can be delivered correctly between IPv6 and IPv4 SIP devices. In the interoperability and performance evaluation experiments, we observe that SIPv6 Translator contribute negligible overheads on call setup time.