Expand Configuration and Management Manual (G06.24+)

Troubleshooting
Expand Configuration and Management Manual—523347-008
21-13
Expand Line-Handler Process Problems
Expand Line-Handler Process Problems
Table 21-7 lists procedures to help you resolve Layer 4 and Layer 2 Expand line-
handler process problems.
Note. You should be familiar with the Expand End-to-End protocol before attempting to
analyze Layer 4 and Layer 2 problems. The End-to-End protocol is described in Path Function
of the Expand Subsystem on page 18-13.
Table 21-7. Expand Line-Handler Process Problem-Resolution Procedures
Problem Procedure
Expand Layer 4
(End-to-End)
protocol
The End-to-End protocol accepts packets for the line(s) from the local
node and passthrough packets destined for other nodes. The End-to-
End protocol also selects the line or manages the interface for the
X25AM subsystem, the SNAX/APN subsystem, the NonStop TCP/IP
subsystem, the Asynchronous Transfer Mode (ATM) subsystem, the
SWAN concentrator, or the ServerNet/FX adapter subsystem.
You can use the Expand subsystem SCF STATS PATH command to
obtain a detailed listing of the Layer 4 statistics.
Layer 4 statistics indicate Layer 4 checksum errors, buffer pool failures,
and out-of-sequence (OOS) errors. These errors can point to the
following problems:
•
Inadequate buffer pool allocation
•
Excessive traffic causing activation of Layer 4 flow control
•
A high number of packets arriving on different lines out of sequence,
contributing to processing overhead
Expand Layer 2
protocol
You can use the SCF STATS LINE command to examine Layer 2
statistics. Figure 21-1
(earlier in this section) is an example of an SCF
STATS LINE command.