TCP/IP (Parallel Library) Configuration and Management Manual

Introduction
HP NonStop TCP/IP (Parallel Library) Configuration and Management Manual—522271-006
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Round-Robin Filtering
robin feature, however, you must explicitly configure it; the default configuration is for
non-round-robin. (See Round-Robin Filtering.)
Subnet-Level Binding: How to Isolate Subnets in a Single-IP
Environment
When you configure the SUBNET object in both conventional TCP/IP and Parallel
Library TCP/IP, you specify a subnet IP address which associates the subnet with a
particular physical interface (PIF). (See ADD SUBNET Command for TCPMAN on
page 5-21.)
In conventional TCP/IP, you could easily isolate an application on a particular subnet
by associating the application with a separate TCP/IP process.
By contrast, in Parallel Library TCP/IP, all applications share a single subnet and
physical interface. In this configuration, you can still achieve application isolation on
particular subnets/PIFs by using subnet-level binding. In Parallel Library TCP/IP, if you
want to force traffic from a particular subnet to go to a particular application, bind the
application to that subnet’s IP address rather than binding the application to
INADDR_ANY. When the application is bound to a particular subnet’s IP address,
TCP/IP directs traffic coming in from that subnet to that socket only. Traffic coming in
from other subnets would not be directed to that socket.
With subnet-level binding, you have a one-to-one correspondence between a PIF and
a socket and correspondingly between an application and that socket. So if you have
multiple application instances, each having performed a subnet-level socket bind, then
traffic coming in on one subnet would go to application one, traffic from the next subnet
would go to application two, and so on.
Alternatively, you can have multiple application instances, each doing INADDR_ANY
socket binds, and causing traffic from any of the subnets that are configured to be
distributed to any of those sockets..
Round-Robin Filtering
Parallel Library TCP/IP uses filters in the adapter to provide a new functionality called
round-robin filtering. Round-robin filtering allows the adapter to distribute incoming
connections to multiple listening processes in different processors sharing the same
port (PIF). Round-robin filtering refers to the distribution of incoming connections to the
first listening process in line, then the second, then the third, and so on, until the last
listening process is reached, at which point the distribution returns again to the first
listening process in line.