engleski

Architecture of SIP Load Balancer

As a consequence of the expected expansion in the number of VoIP technology users in the near future, congestion of nodes that manage VoIP traffic (User Agent Servers - UAS'es) will most likely become a significant problem. This problem can be dealt in two ways: either by using extremely powerful UAS'es or by using traffic balancing among several UAS'es. The latter represents a better solution from economical point of view. It also improves the reliability of the system, potentially increasing the provided quality of service (QoS) as well. Because of SIP's (Session Initiation Protocol) domination among similar VoIP protocols, our work is focused on this protocol. SIP load balancing mechanism has purpose of distributing SIP traffic among several SIP servers using an additional load-balancing device. This device intercepts traffic designated for the SIP domain and directs it to one of the available servers. The load-balancing process is completely transparent to the end user. This work analyzes two basic architectures. The first architecture is called "Flat based" architecture which is network implementation where the IP addresses of the VIP addresses (Virtual IP) and the IP addresses of the real servers are on the same subnet. The second one is known as the NAT-based (Network Address Translator) network architecture, which is network implementation where the IP addresses of the VIP addresses and real servers are on different subnets.

SIP; Load Balancer; Proxy; VoIP; DSR

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