Study On Access Gateway In Next Generation Network

Next Generation Network (NGN) refers to a convergence network with IP as the uniform infrastructure and core, pushing access networks to various services to the edge. In the NGN environment, SIP and H.323 will be two important signaling protocols which are able to function in establishing and terminating sessions.The existence of NAT and private IP addresses breaks network transparency and peer-to-peer connectivity. SIP, which needs the address information contained in the packet payload to complete the session, is not able to complete signaling in a NAT environment. As to the pre-existing H.323 terminals, a certain function is needed to enable their communication with SIP user agents.The two problems raised above can be resolved with a gateway on the network edge. After the analysis of the two problems, this paper investigates into several open-source projects which may be of help to the...