RTP_Relay(局端媒體交換系統)為現今VoIP非常熱門語音交換中心,本論文從電信的角度看待網路電話,在與SIP Proxy整合、RTP封包交互傳送處理、智慧型分散處理、RTP_Relay局端效能分析…等方面做深入研究分析與實作。 另外網路電信系統於現行網路環境下所需面臨的問題,如在NAT(Network Address Translator)與防火牆之下的通訊限制、即時訊息(語音、影像等)傳輸於網路的干擾等之下的影響,提出局端媒體交換的概念與架構。 本論文所提出局端媒體交換系統具有以下特色: 1. RTP_Relay與SIP Proxy搭配相容機制,利用智慧型分散處理演算法,提高媒體交換可靠度,並排除網路延遲可能性。 2. 針對不同NAT型態,提出Firewall內外用戶有效穿越法方法,讓媒體能順利交換。 3. 即時記錄雙方通話資料,如Payload Type、IP Address..等,以便觀察雙方任何媒體資料。 4. 具監聽功能,只需在Public Network,就可監聽欲監聽號碼,並可錄製該媒體檔,以利監控。
Due to the drawback of SIP protocol, the communication between two virtual clients will fail. In this thesis, the RTP_Relay is researched and implemented. The RTP_Relay will co-work with SIP proxy to make the communication between two virtual node successful. In the RTP_Relay system, some subsystems and functions are researched and listed as below: a. Negotiation with SIP Proxy b. RTP packet exchange c. Modified RTP(MRTP) exchange d. TCP80-based RTP exchange e. System capacity improvement f. Distribution architecture design g. Firewall traversal solution