Distributed architecture of VOIP for firewall/NAT Traversing

With the development of the VOIP technology, firewall and NAT become serious problems in network access. Developed from a new technology named SBC (session border controller), this paper proposes distributed architecture to resolve firewall/NAT traversing. To achieve this, SBC is split into two servers: SAG (signaling access gateway) and MCC (media channel controller) to let signaling and media flow pass through separately. In this way, the capacity of VOIP system can achieve great improvement. The limitation depends on the max signaling traffic but not media packets that a SAG can process. The greater significance is that it proposes a fully distributed architecture in which every element can be easily extended and dynamically controlled without any modification on the existing system.