BEA WebLogic Server Tuning Guide

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WebServer is a multi-threaded server but the Plug-in is a single-threaded server. In either case, the serverclasses are
typically configured to have enough headroom to handle peak usage scenarios. Under peak usage, the number of
instances (and hence the QIO resource consumption by the resources) can exhaust the QIO segment space and
lead to application processing failures and potentially processor halts.
3.15 Restricting the List of Ports that Can Be Filtered
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Two additional defines can be used to restrict ports allowed for TCP/IP V6 stack filtering.
TCP/IP V6 stack filtering lets ports be shared by multiple processes. These processes should be running in separate
processors (one per processor) except for multicast sockets, where processes can be on the same or different
processors and there is no restriction on the number of processes joining the same multicast group.
In WebLogic Server configuration, we need TCP/IP V6 stack filtering enabled by default (by specifying the filter
key) as described previously. Unfortunately, this means that all listen ports opened by the WebLogic Server instance
are then considered for filtering. This affects the execution of the instances, if two instances are wrongly configured
with the same IP:port combination.
To avoid this situation, the list of TCP/IP V6 stack filtered ports can be restricted using the following defines, one for
stream sockets and one for datagram sockets. Both defines have the same format.
The define =PTCPIP^FILTER^TCP^PORTS specifies the ports for which the TCP/IP V6 stack software will provide
filtering support. The format is as follows:
$ add_define =PTCPIP^FILTER^TCP^PORTS class=map\
file=P<startport>.P<endport>
where startport and endport are the starting and ending port numbers (inclusive) for which PTCPIP filtering
will be provided.
Similarly, the define =PTCPIP^FILTER^UDP^PORTS specifies the range of UDP ports for which PTCPIP filtering will be
provided.
The recommendation is to specify the define =PTCPIP^FILTER^TCP^PORTS such that it excludes the listen ports used
by all the instances in the cluster. Set =PTCPIP^FILTER^UDP^PORTS to a range of only one port – the multicast port
that is specified in the cluster configuration.
3.16 Ephemeral Ports Configuration
Ports are used in the TCP/IP protocol communication mechanisms to name the ends of logical connections that carry
long-term conversations. For the purpose of providing services to unknown callers, a service contact port is defined
by server processes offering the respective services. For example, a server offering the HTTP service is by default
expected to service requests arriving at the port 80 on a TCP/IP stack.
IANA (Internet Assigned Numbers Authority) defines the port namespace in each TCP stacks into three regions:
• Well Known Ports are those from 0 through 1023.
Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root)
processes or by programs executed by privileged users.
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This is needed only if multiple WebLogic Server instances are configured with the same IP address, but different ports (foregoing the failover capabilities for entity
beans and EJB handles).