Expand Configuration and Management Manual (H06.21+, J06.10+)

Subsystem Description
Expand Configuration and Management Manual — 529522-013
17 - 53
Expand-to-IP Interface
Expand-to-IP Interface
This subsection describes how the Expand-over-IP line-handler process accesses an
Internet Protocol (IP) network. You should be familiar with the information presented in
this subsection before attempting to configure, manage, or troubleshoot an Expand
network that includes IP connections.
Topics discussed in this subsection include
•
NonStop TCP/IP Processes on page 17-53
•
Expand-over-IP Connection Establishment on page 17-54
•
Sending and Receiving Data on page 17-56
•
Forwarding Expand-over-IP Packets to Other Expand Line-Handler Processes on
page 17-56
NonStop TCP/IP Processes
Expand-over-IP line-handler processes do not use the Data Link Layer (OSI Layer 2)
services of the Expand End-to-End protocol; instead, these line-handler processes use
the NETIP protocol at Layer 2 to communicate with a NonStop TCP/IP or NonStop
TCP/IPv6 (TCP6SAM) process. The QIO mechanism is used to transfer data between
the Expand-over-IP line-handler process and its associated NonStop TCP/IP or
TCP6SAM process.
NonStop TCP/IP and TCP6SAM processes provide a Guardian file-system interface to
the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) in
addition to raw (direct) access to the Internet Protocol (IP). (However, raw-socket
support is limited with the NonStop TCP/IPv6 subsystem. For more information on the
raw-socket programming limitations, see the TCP/IP and TCP/IPv6 Programming
Manual. The Expand-over-IP line-handler process uses the UDP services provided by
the TCP/IP subsystem to transmit data across an IP network. UDP is a minimal
datagram protocol that provides a mechanism for identifying the ultimate destination in
a host, such as an application program or other high-level process.
Note. This subsection refers to modifiers that allow you to control various aspects of the
Expand-to-IP interface. For more information on these modifiers, see Section
16, Expand
Modifiers.
Note. Because the QIO mechanism involves data sharing, the Expand-over-IP line-handler
pro
cess and its associated NonStop TCP/IP process must reside in the same processor pair.
However, the TCP/IPv6 architecture removes this restriction, so when the NonStop TCP/IPv6
subsystem is used for TCP/IP connectivity, the Expand-over-IP line-handler process does not
need to reside in the same processor pair as the TCP6SAM process.
Note. The Expand End-to-End protocol already provides the sequencing, error-recovery
, and
congestion control functions that a reliable stream transport service such as TCP/IP provides,
making it unnecessary for the Expand-to-IP interface to duplicate these functions.