test 24781785-BEA-WebLogic | Page 20

Pr od uct io n Ne tw ork Ar ch it ect ur es an d Web Lo gic SI P S er ver Con f igu ra t ion z Multiple engine tier servers arranged in a cluster. z Multiple network channels per engine tier server instance, in support of multiple SIP transport protocols or multiple Network Interface Cards (NICs) on multihomed hardware. z One or more load balancers, or a multihomed load balancer, performing server failover and possibly Network Address Translation (NAT) for source or destination network packets. A combination of these network elements can make it difficult to understand how elements interact with one another, and how a particular combination of elements or configuration options affects the contents of a SIP message or transport protocol datagram. The sections that follow attempt to describe common WebLogic SIP Server network architectures and explain how servers are configured in each architecture. The sections also explain how information in SIP messages and transport datagrams is affected by each configuration. Figure 2-1 shows the typical Open Systems Interconnect (OSI) model layers that can be affected by different network configurations. Figure 2-1 OSI Layers Affected by WebLogic SIP Server Network Configuration Layer 3 (Network) and Layer 4 (Transport) contain the source or destination IP address and port numbers for both outgoing and incoming transport datagrams. Layer 7 (Application) may also be affected because the SIP protocol specifies that certain SIP headers include addressing information for contacting the sender of a SIP message. 2-2 Configuring Network Resources