NS3000/iX Operations and Maintenance Reference Manual (36922-90039)

74 Chapter5
Common Network Problems
Common Problems and Actions
After recovering the file, stop and restart the network transport as
described in Chapter 2, “Operating Your Network,” of this manual.
Incompatible Configuration File Version
Run the NMMGRVER.PUB.SYS program to convert the old configuration
file to the new format. Refer to the Using the NMS Utilities manual for
more information.
Insufficient Configuration File Values
Only change the configured values in the configuration file for a
persistent or widespread problem. The configured values apply to
communication over all the connections and with all the remote nodes
in the internet. The default values are calculated to provide good
performance in a variety of situations. Changes to these values may
improve one situation but affect other situations adversely. If the
recommended action for a particular error or log message is to change
the configured value, do so only for an extremely high number of log
messages or for repeated error messages. Consult your HP
representative for more information.
Retransmission Timeout Errors
The network transport provides reliable end-to-end communication. As
part of ensuring reliable receipt of packets, the transport protocol TCP
keeps track of the packets transmitted. If TCP does not receive an
acknowledgment within the configured time period, TCP retransmits
the packet. If the packet is retransmitted the maximum number of
times configured and is still unacknowledged, then TCP logs a
retransmission timeout error and aborts the connection.
The transport protocol PXP may also log a retransmission timeout
error. This occurs in much the same way as described for TCP, although
PXP retransmits requests, not packets, and waits for replies, not
acknowledgments. PXP is only used whenever an IPCLOOKUP is issued
as part of a NetIPC application, and only communicates with the socket
registry.
Retransmission timeouts can occur for the following reasons:
• Packets were transmitted to a remote node which was not active or
which terminated before the packet arrived.
• Excessive node loads took place during connection establishment.
• The remote node experienced congestion or lack of buffers.
• Possible link or configuration problems.