Multiple Load Balancers and Multihomed Load Balancers
Network Address Translation Options
Production Network Architectures and WebLogic SIP Server Configuration
Multiple Load Balancers and Multihomed Load Balancers
Multiple load balancers( or a multihomed load balancer) can be configured to provide several virtual IP addresses for a single WebLogic SIP Server cluster. To configure WebLogic SIP Server for use with a multihomed load balancer, you create a dedicated network channel for each load balancer or local server NIC, and set the channel’ s public address to the virtual IP address of the appropriate load balancer. In this configuration, the route resolver associates a configured channel with the NIC used for originating SIP messages. The public address of the selected channel is then used for populating SIP system messages. See“ Understanding the Route Resolver” on page 2-7.
Network Address Translation Options
In the most common case, a load balancer is configured using destination NAT to provide a public IP address that clients use for communicating with one or more internal( private) WebLogic SIP Server addresses. Load balancers may also be configured using source NAT, which modifies the Layer 3 address information originating from a private address to match the virtual IP address of the load balancer itself.
With the default route resolver behavior, a WebLogic SIP Server engine originates UDP packets having a source IP address that matches the address of a local NIC( the private address). This can be problematic for applications that try to respond directly to the Layer 3 address embedded in the transport packet, because the local server address may not be publicly accessible. If your applications exhibit this problem, BEA recommends that you configure the load balancer to perform source NAT to change the transport Layer 3 address to a publicly-accessible virtual IP address.
IP Masquerading Alternative to Source NAT
WARNING: Using the WebLogic SIP Server IP masquerading functionality can lead to network instability, because it requires duplicate IP addresses on multiple servers. Production deployments must use a load balancer configured for source NAT, rather than IP masquerading, to ensure reliable network performance.
If you choose not to enable source NAT on your load balancer, WebLogic SIP Server provides limited IP masquerading functionality. To use this functionality, configure a logical address on each engine tier server using the public IP address of the load balancer for the cluster.( Duplicate the same logical IP address on each engine tier server machine). When a local server interface matches the IP address of a configured load balancer( defined in the public address of a network
2-10 Configuring Network Resources