HP-UX TCP/IP Performance White Paper, March 2008

Firewall

Web Server

Load balancer

App Server

DB Server

Open Zone

DMZ MZ

http

https

Enterprise Data Center

Internet/Leased lines

4.1.1 Tuning Application Servers

Network traffic characteristics of a physical server which is used to run as an application server varies

based on its usage context and the nature of applications (business logic) that they run. Web applications

are normally implemented using technologies such as servlets and JSP scripts. For example, users first

connect to the Web server which in turn forwards the request to run an application. Such an application

may be implemented as a servlet on an application server. Based on the application logic, the application

server may need to access the back-end database server. Typically, application servers communicate with

front-end web servers or back-end database servers using a shared set of TCP connections – an approach

known as connection pooling. Typically, Web servers reuse these connections for forwarding the requests

from different clients at different point in time. The connection pooling approach is preferred over creation

of new connections when needed for performance reasons. The number of TCP connections in the pool is

often configurable and is based on the number of concurrent users that the system needs to support during

peak load conditions.

Usually application server vendors may suggest a set of networking related tunable parameters that are best

suited to run the application server on a given OS platform. In this section we provide a set of guidelines on

tuning network tunable parameters to run application servers on HP-UX 11i.

Most of the tunable parameters discussed below are queried or set using ndd command on HP-UX. Please

refer to Appendix B for more details on these tunable parameters.

4.1.1.1 tcp_time_wait_interval

A physical server has to support large number of concurrent TCP connections if it is used to run both an

application server and a Web server simultaneously. tcp_time_wait_interval controls how long

connections need to be in the TIME_WAIT state before closing down. Often opening and closing of a large