NonStop Networking Overview

to the Integrity NonStop system, but the hardware for that legacy networking technology is accessible
only by connecting to a NonStop S-series I/O enclosure. (See Networking Software Products
Available on H-Series and J-Series RVUs (page 10) for a list of all networking products available.)
Integrity NonStop System Networking Compared to Other Platforms
The Integrity NonStop system clustering technology makes it possible for the system to appear as
multiple hosts. Also, the system, when combined with the parallel processing architecture of the
NonStop TCP/IPv6 or CIP product, can appear as a single host while allowing all 16 processors
to service one port. The latter feature allows for high scalability of TCP/IP client applications.
The NonStop TCP/IPv6 and CIP products offer the unique ability to bind multiple servers to a single
port. The listening application instances can run in different processors, bind to a shared IP address
and port, and so service a single IP image with 16 processors of computing power.
This feature, called round-robin filtering, allows for scalability of the listening application (in this
example, the web server process). By sharing a port, the web server process can provide a single-IP
host image to the world through either a single IP address or, in the multi-homed situation, using
DNS round-robin address rotation through multiple IP addresses. In the scenario where the web
server processes are sharing an IP address, the answer that the authoritative name server process
provides for the web server process is the same for all 16 instances of that application server.
Requests that come into the web server process at that IP address are distributed among the 16
web server processes.
For example, you can run a website using iTP Secure WebServer on your Integrity NonStop system,
enable round-robin filtering with NonStop TCP/IPv6 or CIP, and benefit in two ways from the
parallel TCP/IP architecture. First, you can run multiple httpd server processes (the listening processes)
each bound to the same port and IP address; this action scales your httpd server process up to 16
processors. Second, no interprocess hop occurs from the processor containing the listening process
and a processor with TCP/IP access to the communication adapter. CIP extends this functionality
to allow more than one process per processor to serve a single IP address.
NOTE: Round-robin filtering needs to be enabled for NonStop TCP/IPv6 and CIP.
NOTE: NonStop TCP/IPv6 had a limitation of one listening process per processor per port. CIP
does not have this limitation. There can be many listening processes per processor per port.
Additionally, the NonStop TCP/IPv6 and CIP architectures allow direct access from each processor
in a node to the adapter or CLIM. Direct access to the adapter is distinct from the architecture of
conventional NonStop TCP/IP, which can involve an interprocess hop from a processor containing
the TCP/IP stack to the processor containing the application.
For more information about the parallel TCP/IP architecture available on NonStop systems, about
the models for listening applications and how they benefit from this architecture, and for procedures
for configuring the networking environment for round-robin filtering, see the TCP/IPv6 Configuration
and Management Manual. For information about configuring CIP, see the Cluster I/O Protocols
(CIP) Configuration and Management Manual.
NOTE: The models for listening applications described in the TCP/IPv6 Configuration and
Management Manual also apply to CIP.
For information about the iTP Secure WebServer, see the iTP Secure WebServer System
Administrator’s Guide.
The remainder of this subsection details the unique characteristics of networking in the NonStop
system environment.
You can use various methods for scaling your DNS implementation, some of which are unique to
the NonStop system and some of which are enhanced by the NonStop system architecture. You
can also use various methods for scaling your network interface capacity as well as scaling your
application through DNS capabilities.
What’s Unique About Networking on Integrity NonStop Systems 15