TCP/IP Configuration and Management Manual

NonStop TCP/IP Processes and Protocols
TCP/IP Configuration and Management Manual—427132-004
B-19
NonStop TCP/IP as a NonStop Process Pair
NonStop TCP/IP as a NonStop Process Pair
Run the NonStop TCP/IP process as a NonStop process pair. When running the
process as a NonStop pair, the primary process attempts to start the backup process
as it completes its initialization. Should the attempt fail, the primary process delays for
a period, then attempts to start the backup process again. After each attempt, the
primary process delays for a slightly longer interval prior to attempting the restart until
the interval reaches a maximum value of 10 minutes.
The primary NonStop TCP/IP process keeps the backup process ready to take over by
checkpointing all configuration changes and socket creation, and deletion and state
changes. A NonStop TCP/IP process provides a persistent TCP/IP process, which
recovers from processor failure and SCF primary requests.
If the backup process of a TCP/IP NonStop pair abends for any reason, the primary
process tries to restart the backup process after a delay. This delay increases after
each failure until it reaches a maximum of 10 minutes. An EMS message is issued
when the backup process has abended and displays the time after which the primary
process attempts to create the backup. The period for recovery initially begins at 5
seconds with a maximum delay of 10 minutes. The period is reset to the initial value
each time the backup processor is reloaded. When the backup process abends, it
Figure B-12. Layered Architecture of NonStop TCP/IP Software
031VST .VSD
IP with ICMP and
ARP
Other
User
Appli-
cations
FTP ECHO FINGE
R
SMTP
TELNET
TN6530
TCP UDP
LLC1 filter
IP filter
SLSA driver/interrupt handler
ARP filter
DOMAIN
NAME
SERVER
(DNS)
TFTP
Other
Services