Improving the DNS mechanism in a data center intranet

Abstract

The Internet Protocol (IP) Multimedia Subsystem (IMS) is an architecture for supporting multimedia services via a Session Initiation Protocol (SIP) infrastructure. IMS is specified in technical releases of the 3rd Generation Partnership Project (3GPP <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> ). With IMS (and similar architecture), each call instance will require many SIP components to interwork, in order to provide the service. Many of them are typically installed together, in a data center in an office building. Between those components, the regular and standard way to obtain the IP address and port number of others is to resolve their unified resource identifier (URI) using the domain name system (DNS). This approach has several drawbacks: it uses CPU resources to retrieve the data, the data may be obsolete, and it does not take into account the actual availability of the peer node. When several peer nodes can fulfill the request, round robin distribution is usually used and thus ignores the actual occupation of the peers. No admission control is provided, and overloaded peer nodes will continue to be used even through other nodes are less heavily loaded. This paper will describe how the Alcatel-Lucent Session Manager has resolved those problems using a generic solution, applicable when many signaling nodes in an office building need to communicate with each other. An important aspect is that this solution is transparent to the applications and is integrated with DNS. © 2007 Alcatel-Lucent.