Refer to the following section for details about the new feature released in version 7.2.60.1.

Ephemeral Port Range Selection

“Ephemeral ports” refers to the range of source ports used by the system for initiating outbound communications, particularly to Real Servers. By default (as recommended in RFC 6506) the LoadMaster uses a wide range of ports for ephemeral port selection – ports 1024 through 63999.

Some customers may require the ability to restrict the port range used for ephemeral port selection, so that dedicated ports used by specific applications on Real Servers can be excluded from the port selection process.

Starting with this release, the System Configuration > Miscellaneous Options > Network Options > Local Reserved Ports parameter allows you to specify a list of ports that will be excluded from the source port selection process. Some things to note about the Local Reserved Ports are as follows:

  • You can specify a single port (or a list of comma-separated ports) that will not be used when initiating connections to Real Servers.
  • Ports specified in the list must be between 1024 and 63999, inclusive.
  • A port cannot appear more than once in the list.
  • The total length of the list cannot exceed 128 characters.
  • When making changes to an existing list, the entire list of ports must be specified.
Warning: Significantly reducing the number of ports available for connections to Real Servers could lead to port exhaustion (that is, dropped server-side connections) during heavy traffic periods. Best practice is to keep the number of ports removed low – a single-digit percentage of all ports.