Do Not Share the Cluster Multicast Address with Other Applications Although If Multicast Storms Occur If server instances in a cluster do not process
3.1.1.1.2 Firewalls Can Break Multicast Communication Although it may be possible to
tunnel multicast traffic through a firewall, this practice is not recommended for WebLogic Server clusters. Treat each WebLogic Server cluster as a logical unit that provides one or more distinct services to clients of a Web application. Do not split this logical unit between different security zones. Furthermore, any technologies that potentially delay or interrupt IP traffic can disrupt a WebLogic Server cluster by generating false failures due to missed heartbeats.3.1.1.1.3 Do Not Share the Cluster Multicast Address with Other Applications Although
multiple WebLogic Server clusters can share a single IP multicast address and port, other applications should not broadcast or subscribe to the multicast address and port used by your cluster or clusters. That is, if the machine or machines that host your cluster also host other applications that use multicast communications, make sure that those applications use a different multicast address and port than the cluster does. Sharing the cluster multicast address with other applications forces clustered server instances to process unnecessary messages, introducing overhead. Sharing a multicast address may also overload the IP multicast buffer and delay transmission of WebLogic Server heartbeat messages. Such delays can result in a WebLogic Server instance being marked as failed, simply because its heartbeat messages were not received in a timely manner. For these reasons, assign a dedicated multicast address for use by WebLogic Server clusters, and ensure that the address can support the broadcast traffic of all clusters that use the address.3.1.1.1.4 If Multicast Storms Occur If server instances in a cluster do not process
incoming messages on a timely basis, increased network traffic, including negative acknowledgement NAK messages and heartbeat re-transmissions, can result. The repeated transmission of multicast packets on a network is referred to as a multicast storm, and can stress the network and attached stations, potentially causing end-stations to hang or fail. Increasing the size of the multicast buffers can improve the Note: Distributing a WebLogic Server cluster over a WAN may require network facilities in addition to the multicast requirements described above. For example, you may want to configure load balancing hardware to ensure that client requests are directed to server instances in the most efficient manner to avoid unnecessary network hops. 3-4 Using Clusters for Oracle WebLogic Server rate at which announcements are transmitted and received, and prevent multicast storms. See Section 10.2.18.3, Configure Multicast Buffer Size.3.1.2 One-to-Many Communication Using Unicast
Parts
» Oracle Fusion Middleware Online Documentation Library
» Document Scope and Audience Guide to this Document
» What Are the Benefits of Clustering? What Are the Key Capabilities of a Cluster?
» Servlets and JSPs EJBs and RMI Objects
» Getting Connections with Clustered JDBC Failover and Load Balancing for JDBC Connections
» Pure-Java Versus Native Socket Reader Implementations
» Client Communication via Sockets
» How WebLogic Server Creates the Cluster-Wide JNDI Tree
» How WebLogic Server Updates the JNDI Tree Client Interaction with the Cluster-Wide JNDI Tree
» Load Balancer Configuration Requirements Load Balancers and the WebLogic Session Cookie
» Related Programming Considerations How Session Connection and Failover Works with a Load Balancer
» Round-Robin Load Balancing Weight-Based Load Balancing
» Transactional Collocation Optimization for Collocated Objects
» Methods of Configuring Clusters Load Balancing for JDBC Connections
» Using Replication Groups HTTP Session State Replication
» Connection with Load Balancing Hardware Failover with Load Balancing Hardware
» Configuration Requirements for Cross-Cluster Replication
» Configuring Session State Replication Across Clusters
» Clustering Objects with Replica-Aware Stubs
» Failover and JDBC Connections Understanding Server and Service Migration
» Migration Terminology Oracle Fusion Middleware Online Documentation Library
» Features That Use Leasing Leasing Versions
» Determining Which Type of Leasing To Use High-availability Database Leasing
» Non-database Consensus Leasing Leasing
» Preparing for Automatic Whole Server Migration
» Configuring Automatic Whole Server Migration
» Startup Process in a Cluster with Migratable Servers
» Automatic Whole Server Migration Process
» Manual Whole Server Migration Process Administration Server Role in Whole Server Migration
» Migratable Server Behavior in a Cluster Node Manager Role in Whole Server Migration
» Cluster Master Role in Whole Server Migration
» JMS-related Services JTA Transaction Recovery Service
» Custom Store Availability for JMS Services Default File Store Availability for JTA
» Best Practices for Targeting JMS when Configuring Automatic Service Migration
» Architecture Web Application Tiers
» Combined Tier Architecture De-Militarized Zone DMZ Load Balancer Proxy Plug-In
» No Collocation Optimization Firewall Restrictions
» Multi-Tier Proxy Architecture Proxy Architecture Benefits Proxy Architecture Limitations
» Proxy Plug-In Versus Load Balancer
» DMZ with Two Firewall Configuration
» Dynamic Cluster Address If you do not explicitly define a cluster address
» Configuration Roadmap Install WebLogic Server
» Starting a WebLogic Server Cluster
» Configure Node Manager Configure Load Balancing Method for EJBs and RMIs
» Sample web.xml This section contains a sample deployment descriptor file
» Accessing Applications Via the Proxy Server Ensure that applications clients will
» Configure Replication Groups Configure Migratable Targets for Pinned Services
» Migrating When the Currently Active Host is Unavailable Use this migration
» Configure Multicast Time-To-Live TTL Configure Multicast Buffer Size
» Cluster-Related Configuration Options Follow Usage and Configuration Guidelines
» Manual Migration of the JTA Transaction Recovery Service State Management in a Cluster
» Naming Considerations Administration Server Considerations
» Firewall Considerations Avoiding Problems
» Check the Server Version Numbers Check the Multicast Address Check the CLASSPATH Value
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