Expand Configuration and Management Manual (G06.24+)

Configuring Expand-Over-IP Lines
Expand Configuration and Management Manual—523347-008
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NonStop TCP/IP Process
NonStop TCP/IP Process
The Expand-over-IP line-handler process uses the services of a NonStop TCP/IP
process to provide TCP/IP connectivity. The NonStop TCP/IP process and SUBNET
associated with the Expand-over-IP line-handler process must be defined and started
before the Expand-over-IP line-handler process can be started. It must be configured
in the same processor pair as the Expand-over-IP line-handler process.
For information about configuring and managing NonStop TCP/IP processes, refer to
the TCP/IP Configuration and Management Manual.
Parallel Library TCP/IP and NonStop TCP/IPv6 Processes
Parallel Library TCP/IP and NonStop TCP/IPv6 can also provide TCP/IP connectivity
for the Expand-over-IP line-handler process. NonStop TCP/IPv6 can optionally provide
support for IP version 6 communications and also has a feature called logical network
partitioning (LNP) that allows you to configure the line-handler process such that it only
has access to a configured set of IP addresses. (In both Parallel Library TCP/IP and
NonStop TCP/IPv6 without LNP, the Expand line-handler process has access to all the
IP addresses in the subsystem.) Both products provide performance enhancements
and eliminate the need to configure the line-handler processes in the same CPU pair
as the TCP/IP processes. In addition, both Parallel Library TCP/IP and NonStop
TCP/IPv6 provide Ethernet failover capabilities. (Parallel Library TCP/IP and NonStop
TCP/IPv6 only support Ethernet adapters.)
The line handler supports the 128-bit addressing scheme used in IPv6
communications, as well as the 32-bit addresses used by IPv4.
Redundancy in Ethernet Adapters
Redundancy in Ethernet adapters and IP network routes can be applied by multi-line
Expand-over-IP paths and multi-CPU paths, where the member paths are Expand-
over-IP. These configurations offer multiple, parallel connections between a NonStop
system and one of its neighbors. With these configurations, there is potentially greater
bandwidth and fault tolerance. For the full benefit to exist, however, all elements,
including the network itself, must have redundancy.
The decision of which adapter/path to apply for a particular Expand connection in
conventional NonStop TCP/IP and in LNP-configured NonStop TCP/IPv6 is made
explicitly by how you configure the adapters, NonStop TCP/IP processes, and lines.
This selection is independent of the external network. The adapters and lines will be
applied in parallel, but if there is no redundancy in the network to which they connect,
the effectiveness of the parallelism is considerably reduced. In these cases, the fault-
tolerance decisions made in Expand for multi-line IP paths may be disruptive rather
than helpful.
Parallel Library TCP/IP and NonStop TCP/IPv6 configured without LNP make a
dynamic choice of which adapter/line to employ, among any configured redundant
assortment, based on the destination address of the IP connection and the best route