System information

Troubleshooting X.25 Connections 19-417
X.25: Excess Serial Errors on X.25 Link
X.25: Excess Serial Errors on X.25 Link
Symptom: The output of the show interfaces serial command shows REJs, RNRs, FRMRs,
RESTARTs, or DISCs in excess of 0.5% of information frames (IFRAMEs).
Note If any of these fields are increasing and represent more than 0.5% of the number of IFRAMEs,
there is probably a problem somewhere in the X.25 network. There should always be at least one
SABM. However, if there are more than 10, the packet switch probably is not responding.
Table 19–2 outlines the problem that might cause this symptom and describes solutions to that
problem.
Table 19-2 X.25: Excess Serial Errors on X.25 Link
Misconfigured x25 map command
Step 1 Use the show running-config privileged exec command to view the
router configuration. Look for x25 map interface configuration
command entries.
Step 2 Make sure that x25 map commands specify the correct address
mappings.
To retract a prior mapping, use the no form of the x25 map
command with the appropriate network protocol(s) and X.121
address argument:
no x25 map protocol address x121-address
To set up the LAN protocols-to-remote host mapping, use the x25
map interface configuration command:
x25 map protocol address [protocol2 address2[...[protocol9
address9]]] x121-address [option]
Misconfigured x25 map command Syntax Description:
• protocol—Protocol type, entered by keyword. Supported protocols
are entered by keyword. As many as nine protocol and address
pairs can be specified in one command line.
• address—Protocol address.
• x121-address—X.121 address of the remote host.
• option—(Optional) Additional functionality that can be specified
for originated calls.
Step 3 Ensure that all router X.25 configuration options match the settings
of attached switches. Reconfigure the router or switch as necessary.
Step 4 Enable the debug x25 events command and look for RESTART
messages (for PVCs) or CLEAR REQUESTs with nonzero cause
codes (for SVCs).
To interpret X.25 cause and diagnostic codes provided in the debug
x25 events output, refer to the Debug Command Reference.
1 LAPB = Link Access Procedure, Balanced
2 UA = Unnumbered Ack
3 SAMB = Set Asynchronous Balance Mode
4 PVC = permanent virtual circuit
5 SVC = switched virtual circuit
Possible Problem Solution