Configuring Timer Affinity Optional

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6. Click Save to save your configuration changes.

Note that the Enable Timer Affinity setting is persisted in sipserver.xml in the element, enable-timer-affinity.

3.5.2 Configuring NTP for Accurate SIP Timers

In order for the SIP protocol stack to function properly, all engine and SIP data tier servers must accurately synchronize their system clocks to a common time source, to within one or two milliseconds. Large differences in system clocks cause a number of severe problems such as: ■ SIP timers firing prematurely on servers with fast clock settings. ■ Poor distribution of timer processing in the engine tier. For example, one engine tier server may process all expired timers, whereas other engine tier servers process no timers. Oracle recommends using a Network Time Protocol NTP client or daemon on each Oracle WebLogic Communication Services instance and synchronizing to a common NTP server. Caution: You must accurately synchronize server system clocks to a common time source to within one or two milliseconds in order for the SIP protocol stack to function properly. Because the initial T1 timer value of 500 milliseconds controls the retransmission interval for INVITE request and responses, and also sets the initial values of other timers, even small differences in system clock settings can cause improper SIP protocol behavior. For example, an engine tier server with a system clock 250 milliseconds faster than other servers will process more expired timers than other engine tier servers, will cause retransmits to begin in half the allotted time, and may force messages to timeout prematurely. 4 Managing Network Resources 4-1 4 Managing Network Resources The following sections describe how to configure network resources for use with Oracle WebLogic Communication Services: ■ Section 4.1, Overview of Network Configuration ■ Section 4.2, Configuring Load Balancer Addresses ■ Section 4.3, Enabling Domain Name Service DNS Support ■ Section 4.4, Configuring Network Channels for SIP or SIPS ■ Section 4.5, Configuring TCP and TLS Channels for Diameter Support ■ Section 4.6, Configuring Engine Servers to Listen on Any IP Interface ■ Section 4.7, Configuring Unique Listen Address Attributes for SIP Data Tier Replicas

4.1 Overview of Network Configuration

The default HTTP network configuration for each Oracle WebLogic Communication Services instance is determined from the Listen Address and Listen Port setting for each server. However, Oracle WebLogic Communication Services does not support the SIP protocol over HTTP. The SIP protocol is supported over the UDP and TCP transport protocols. SIPS is also supported using the TLS transport protocol. To enable UDP, TCP, or TLS transports, you configure one or more network channels for a Oracle WebLogic Communication Services instance. A network channel is a configurable WebLogic Server resource that defines the attributes of a specific network connection to the server instance. Basic channel attributes include: ■ The protocols supported by the connection ■ The listen address DNS name or IP address of the connection ■ The port number used by the connection ■ optional The port number used by outgoing UDP packets ■ The public listen address load balancer address to embed in SIP headers when the channel is used for an outbound connection. You can assign multiple channels to a single Oracle WebLogic Communication Services instance to support multiple protocols or to utilize multiple interfaces available with multi-homed server hardware. You cannot assign the same channel to multiple server instances. When you configure a new network channel for the SIP protocol, both the UDP and TCP transport protocols are enabled on the specified port. You cannot create a SIP