TCP/IP Configuration and Management Manual

NonStop TCP/IP Processes and Protocols
TCP/IP Configuration and Management Manual—427132-004
B-20
TN6530 Emulation Utility
creates a save abend dump file. The save file created only contains the stack area of
the process and not the full QIO segment. If the backup abends during its initialization
code, no save abend file is created.
TN6530 Emulation Utility
The multiple-page terminal emulation utility (TN6530) is a UNIX TELNET client that
interfaces to NonStop TCP/IP and TELSERV. TN6530 emulates a 6530 terminal,
including its block-mode support. TN6530 allows a user on a UNIX system to connect
to a NonStop system and run applications that require a multiple-page terminal such as
the 6530. Figure B-13
shows the software layout of the TN6530 utility and its
relationship to the Internet.
Transmission Control Protocol (TCP)
The Transmission Control Protocol (TCP) is used by applications that require reliable
end-to-end data transfer. It is a stream-oriented protocol that has no concept of packet
boundaries. TCP guarantees that all data sent will be received and will arrive in the
same order in which it was sent.
The NonStop TCP/IP process provides a socket interface to the Transmission Control
Protocol (TCP, RFC 793), which uses Guardian file-system procedures for interprocess
communication. TCP is a stream-oriented protocol with no concept of record
boundaries.
Application processes call a socket routine to request that the NonStop TCP/IP
software create a socket when needed; the application specifies the type of service.
Port Numbers
Both TCP and UDP use a 16-bit port number to select a socket on the host. Client
programs normally use more-or-less random port numbers; however, specific port
numbers (called well-known ports) are assigned for use by server programs. Each
well-known port is associated with a specific service. A client requesting a particular
service specifies as the destination port the well-known port associated with that
service. The server program listens at that port for requests. The well-known port
numbers are listed in Appendix C, Well-Known Port Numbers for TCP and UDP
.
Figure B-13. TN6530 Software Layout and Relationship to Internet
032VST .VSD
User Terminal
6530
Display Routines
TELNET
Protocol
TCP/IP
Network
6530
Keyboard Mapping