H3C S12500G-AF Series User manual

H3C S12500G-AF Switch Series
Troubleshooting Guide
Software version: Release 7595
Document version: 6W100-20200930
Copyright © 2020 New H3C Technologies Co., Ltd. All rights reserved.
No part of this manual may be reproduced or transmitted in any form or by any means without prior written consent of New
H3C Technologies Co., Ltd.
Except forthe trademarks of NewH3C Technologies Co.,Ltd., anytrademarks that may be mentioned in this document are
the property of their respective owners.
The information in this document is subject to change without notice.

i
Contents
Introduction····································································································1
General guidelines·············································································································································1
Collecting log and operating information············································································································1
Collecting common log messages ·············································································································2
Collecting diagnostic log messages···········································································································4
Collecting operating statistics·····················································································································5
Contacting technical support······························································································································9
Removing deployment errors·······································································10
Dealing with password loss··········································································16
Dealing with console login password loss········································································································16
Telnetting to the device to change the console login password·······························································16
Using BootWare menus to change the console login password······························································17
Dealing with Telnet password loss···················································································································21
Troubleshooting configuration loss ······························································23
Startup configuration file failure························································································································23
Symptom··················································································································································23
Solution····················································································································································23
Related commands··········································································································································24
Troubleshooting hardware···········································································25
MPU reboot failure···········································································································································25
Symptom··················································································································································25
Troubleshooting flowchart························································································································25
Solution····················································································································································25
Newly installed standby MPU boot failure········································································································26
Symptom··················································································································································26
Troubleshooting flowchart························································································································26
Solution····················································································································································27
Service module reboot failure··························································································································27
Symptom··················································································································································27
Troubleshooting flowchart························································································································27
Solution····················································································································································27
Newly installed service module boot failure·····································································································28
Symptom··················································································································································28
Troubleshooting flowchart························································································································29
Solution····················································································································································29
Operating power module failure·······················································································································30
Symptom··················································································································································30
Troubleshooting flowchart························································································································31
Solution····················································································································································31
Newly installed power module failure···············································································································33
Symptom··················································································································································33
Troubleshooting flowchart························································································································33
Solution····················································································································································33
Fan tray failure·················································································································································34
Symptom··················································································································································34
Troubleshooting flowchart························································································································35
Solution····················································································································································35
Related commands··········································································································································36
Troubleshooting system management·························································37
High CPU usage on a module··························································································································37
Symptom··················································································································································37
Troubleshooting flowchart························································································································37

ii
Solution····················································································································································37
High memory usage on a module····················································································································39
Symptom··················································································································································39
Troubleshooting flowchart························································································································39
Solution····················································································································································39
Temperature alarms·········································································································································41
Symptom··················································································································································41
Troubleshooting flowchart························································································································42
Solution····················································································································································42
Related commands··········································································································································42
Troubleshooting ports··················································································44
10-Gigabit SFP+ fiber port fails to come up·····································································································44
Symptom··················································································································································44
Troubleshooting flowchart························································································································45
Solution····················································································································································45
40-GE QSFP+ fiber port fails to come up ········································································································46
Symptom··················································································································································46
Troubleshooting flowchart························································································································47
Solution····················································································································································47
100-GE QSFP28 fiber port fails to come up·····································································································48
Symptom··················································································································································48
Troubleshooting flowchart························································································································48
Solution····················································································································································48
Reporting non-H3C transceiver modules·········································································································49
Symptom··················································································································································49
Troubleshooting flowchart························································································································50
Solution····················································································································································50
Failure to support digital diagnosis on a transceiver module···········································································50
Symptom··················································································································································50
Troubleshooting flowchart························································································································51
Solution····················································································································································51
Error frames (for example, CRC errors) on a port····························································································51
Symptom··················································································································································51
Troubleshooting flowchart························································································································52
Solution····················································································································································52
Failure to receive packets································································································································54
Symptom··················································································································································54
Troubleshooting flowchart························································································································54
Solution····················································································································································54
Failure to send packets····································································································································55
Symptom··················································································································································55
Troubleshooting flowchart························································································································56
Solution····················································································································································56
Related commands··········································································································································57
Troubleshooting IRF····················································································58
IRF fabric setup failure·····································································································································58
Symptom··················································································································································58
Troubleshooting flowchart························································································································59
Solution····················································································································································60
IRF split····························································································································································61
Symptom··················································································································································61
Troubleshooting flowchart························································································································62
Solution····················································································································································62
BFD MAD failure··············································································································································62
Symptom··················································································································································62
Troubleshooting flowchart························································································································63
Solution····················································································································································63
LACP MAD failure············································································································································65
Symptom··················································································································································65
Troubleshooting flowchart························································································································65

iii
Solution····················································································································································65
Related commands··········································································································································66
Troubleshooting QoS and ACL····································································68
ACL application failure for unsupported ACL rules··························································································68
Symptom··················································································································································68
Troubleshooting flowchart························································································································68
Solution····················································································································································68
ACL application failure for insufficient resources·····························································································68
Symptom··················································································································································68
Troubleshooting flowchart························································································································69
Solution····················································································································································69
ACL application failure without an error message····························································································70
Symptom··················································································································································70
Troubleshooting flowchart························································································································70
Solution····················································································································································71
Related commands··········································································································································71
Troubleshooting MDC··················································································72
Service module assignment failure··················································································································72
Symptom··················································································································································72
Troubleshooting flowchart························································································································72
Solution····················································································································································72
Interface assignment failure·····························································································································74
Symptom··················································································································································74
Troubleshooting flowchart························································································································74
Solution····················································································································································74
Related commands··········································································································································77
Troubleshooting DRNI·················································································78
DR system setup failure···································································································································78
Symptom··················································································································································78
Troubleshooting flowchart························································································································78
Solution····················································································································································78
DR system split················································································································································79
Symptom··················································································································································79
Troubleshooting flowchart························································································································80
Solution····················································································································································80
Member ports of a DR interface cannot be selected························································································81
Solution····················································································································································81
Troubleshooting flowchart························································································································81
Solution····················································································································································81
Related commands··········································································································································82

1
Introduction
This document provides information about troubleshooting common software and hardware issues
with H3C S12500G-AF switches.
General guidelines
IMPORTANT:
To prevent an issue from causing loss of configuration, save
the configuration each time you finish
configuring a feature. For configuration recovery, regularly back up the configuration to a remote
server.
When you troubleshoot the switch, follow these general guidelines:
•
To help identify the cause of the issue, collect system and configuration information, including:
Symptom, time of failure, and configuration.
Network topology information, including the network diagram, port connections, and points
of failure.
Log messages and diagnostic information. For more information about collecting this
information, see "Collecting log and operating information."
Physical evidence of failure:
−Photos of the hardware.
−Status of the card, power, and fan status LEDs.
Steps you have taken, such as reconfiguration, cable swapping, and reboot.
Output from the commands executed during the troubleshooting process.
•
To ensure safety, wear an ESD wrist strap when you replace or maintain a hardware
component.
•
If hardware replacement is required, use the release notes to verify the hardware and software
compatibility.
Collecting log and operating information
IMPORTANT:
By default, the information center is enabled. If the feature
is disabled, you must use the
info-center enable command to enable the feature for collecting log messages.
Table 1 shows the types of files that the system uses to store operating log and status information.
You can export these files by using FTP or TFTP.
These files are stored on the active MPU (in standalone mode) or global active MPU (in IRF mode).
Multiple MPUs will have log files if active/standby or master/subordinate switchovers have occurred.
You must collect log files from all these MPUs. To more easily locate log information, use a consistent
rule to categorize and name files. For example, save log information files to a separate folder for
each MPU, and include their chassis and slot numbers in the folder names.
Table 1 Log and operating information
Category
File name format
Content
Common log logfile.log Command execution and operational log messages.

2
Category
File name format
Content
Diagnostic log diagfile.log
Diagnostic log messages about device operation, including the
following items:
•Parameter settings in effect when an error occurs.
•Information about a card startup error.
•Handshaking information between the MPU and interface
module when a communication error occurs.
Operating
statistics file-basename.gz
Current operating statistics for feature modules, including the
following items:
•Device status.
•CPU status.
•Memory status.
•Configuration status.
•Software entries.
•Hardware entries.
Collecting common log messages
1. Save common log messages from the log buffer to a log file:
By default, the log file is saved in the logfile directory of the flash memory on the active MPU (in
standalone mode) or global active MPU (in IRF mode).
# Save log messages to the log file on the default MDC (Admin).
<Sysname> logfile save
The contents in the log file buffer have been saved to the file
flash:/logfile/logfile1.log
# Identify non-default MDCs created on the device.
<Sysname> display mdc
ID Name Status
---------------------------------
1 Admin active
2 mdc2 active
3 mdc3 active
# Save log messages to the log file on each non-default MDC.
<Sysname> system-view
[Sysname] switchto mdc mdc2
******************************************************************************
* Copyright (c) 2004-2020 New H3C Technologies Co., Ltd. All rights reserved.*
* Without the owner's prior written consent, *
* no decompiling or reverse-engineering shall be allowed. *
******************************************************************************
<Sysname> logfile save
The contents in the log file buffer have been saved to the file
flash:/logfile/logfile1.log
<Sysname> switchback
[Sysname] switchto mdc 3
******************************************************************************
* Copyright (c) 2004-2020 New H3C Technologies Co., Ltd. All rights reserved.*

3
* Without the owner's prior written consent, *
* no decompiling or reverse-engineering shall be allowed. *
******************************************************************************
<Sysname> logfile save
The contents in the log file buffer have been saved to the file
flash:/logfile/logfile1.log
<Sysname> switchback
2. On the default MDC, identify the log file on each MPU for each MDC:
# Display the log file on the active MPU (in standalone mode) or global active MPU (in IRF
mode) for the default MDC.
<Sysname> dir flash:/logfile/
Directory of flash:/logfile
0 -rw-97764 Apr 27 2020 15:55:32 logfile1.log
3710740 KB total (2508852 KB free)
# Display the log file on each standby MPU for the default MDC:
In standalone mode, display the log file on the standby MPU.
<Sysname> dir slot1#flash:/logfile/
Directory of slot1#flash:/logfile
0 -rw-21863 Apr 27 2020 16:00:37 logfile1.log
3710740 KB total (3002308 KB free)
In IRF mode, display the log file on each standby MPU.
<Sysname> dir chassis2#slot1#flash:/logfile/
Directory of chassis2#slot1#flash:/logfile
0 -rw-21863 Apr 27 2020 16:00:37 logfile1.log
3710740 KB total (3273812 KB free)
NOTE:
If a subordinate chassis has two MPUs, make sure you identify and export
the log files on
both MPUs.
# Display the log file on each MPU for each non-default MDC.
<Sysname> dir flash:/mdc/
Directory of flash:/mdc
0 drw-- Apr 27 2020 14:56:50 mdc2
1 drw-- Apr 27 2020 16:48:04 mdc3
<Sysname> dir flash:/mdc/mdc2/logfile/
Directory of flash:/mdc/mdc2/logfile
0 -rw-465 Apr 27 2020 16:08:51 logfile1.log
3710740 KB total (2508852 KB free)
<Sysname> dir flash:/mdc/mdc3/logfile/
Directory of flash:/mdc/mdc3/logfile
0 -rw-465 Apr 27 2020 16:10:39 logfile1.log

4
3710740 KB total (2508852 KB free)
3. Transfer the files to the desired destination by using FTP or TFTP. (Details not shown.)
Collecting diagnostic log messages
1. Save diagnostic log messages from the diagnostic log file buffer to a diagnostic log file:
By default, the diagnostic log file is saved in the diagfile directory of the flash memory on each
MPU.
# Save diagnostic log messages to the diagnostic log file on the default MDC (Admin).
<Sysname> diagnostic-logfile save
The contents in the diagnostic log file buffer have been saved to the file
flash:/diagfile/diagfile1.log
# Identify non-default MDCs created on the device.
<Sysname> display mdc
ID Name Status
---------------------------------
1 Admin active
2 mdc2 active
3 mdc3 active
# Save diagnostic log messages to the diagnostic log file on each non-default MDC.
<Sysname> system-view
[Sysname] switchto mdc mdc2
******************************************************************************
* Copyright (c) 2004-2020 New H3C Technologies Co., Ltd. All rights reserved.*
* Without the owner's prior written consent, *
* no decompiling or reverse-engineering shall be allowed. *
******************************************************************************
<Sysname> diagnostic-logfile save
The contents in the diagnostic log file buffer have been saved to the file
flash:/diagfile/diagfile1.log
<Sysname> switchback
[Sysname] switchto mdc 3
******************************************************************************
* Copyright (c) 2004-2020 New H3C Technologies Co., Ltd. All rights reserved.*
* Without the owner's prior written consent, *
* no decompiling or reverse-engineering shall be allowed. *
******************************************************************************
<Sysname> diagnostic-logfile save
The contents in the diagnostic log file buffer have been saved to the file
flash :/diagfile/diagfile1.log
<Sysname> switchback
2. On the default MDC, identify the diagnostic log file on each MPU for each MDC:
# Display the diagnostic log file on the active MPU (in standalone mode) or global active MPU
(in IRF mode) for the default MDC.
<Sysname> dir flash:/diagfile/
Directory of flash:/diagfile

5
0 -rw-161321 Apr 27 2020 16:16:00 diagfile1.log
3710740 KB total (2508852 KB free)
# Display the diagnostic log file on each standby MPU for the default MDC:
In standalone mode, display the diagnostic log file on the standby MPU.
<Sysname> dir slot1#flash:/diagfile/
Directory of flash:/diagfile
0 -rw-161321 Apr 27 2020 16:16:00 diagfile1.log
3710740 KB total (2508852 KB free)
In IRF mode, display the diagnostic log file on each standby MPU.
<Sysname> dir chassis2#slot0#flash:/diagfile/
Directory of chassis2#slot0#flash:/diagfile
0 -rw-161321 Apr 27 2020 16:16:00 diagfile1.log
3710740 KB total (3002308 KB free)
NOTE:
If a subordinate chassis has two MPUs, make sure you identify and export
the diagnostic log
files on both MPUs.
# Display the diagnostic log file on each MPU for each non-default MDC.
<Sysname> dir flash:/mdc/
Directory of flash:/mdc
0 drw-- Apr 27 2020 14:56:50 mdc2
1 drw-- Apr 27 2020 16:48:04 mdc3
<Sysname>dir flash:/diagfile/
Directory of flash:/diagfile
0 -rw-349 Apr 27 2020 16:21:38 diagfile1.log
3710740 KB total (2508852 KB free)
<Sysname> dir flash:/diagfile/
Directory of flash:/diagfile
0 -rw-349 Apr 27 2020 16:24:41 diagfile1.log
3710740 KB total (2508852 KB free)
3. Transfer the files to the desired destination by using FTP or TFTP. (Details not shown.)
Collecting operating statistics
You can collect operating statistics by saving the statistics to a file or displaying the statistics on the
screen.
When you collect operating statistics, follow these guidelines:
•
Log in to the device through a network port or management port instead of the console port, if
possible. Network and management ports are faster than the console port.
•
Do not execute commands while operating statistics are being collected.
•
As a best practice, save operating statistics to a file to retain the information.

6
To collect operating statistics:
1. Disable pausing between screens of output if you want to display operating statistics on the
screen. Skip this step if you are saving statistics to a file.
<Sysname> screen-length disable
2. Execute the display cpu-usage and display memory commands to verify that the CPU
usage is lower than 100% and the memory usage is lower than 90%.
<Sysname> display cpu-usage
...
<Sysname> display memory
...
3. Collect operating statistics for multiple feature modules.
<Sysname> display diagnostic-information
Save or display diagnostic information (Y=save, N=display)? [Y/N] :
4. At the prompt, choose to save or display operating statistics:
# To save operating statistics, enter yat the prompt and then specify the destination file path.
Save or display diagnostic information (Y=save, N=display)? [Y/N]:y
Please input the file name(*.tar.gz)[flash:/diag_H3C_20200523-151204.tar.gz]:
Diagnostic information is outputting to flash:/diag_H3C_20200523-151204.tar.gz.
Please wait...
Save successfully.
<Sysname> dir flash:/
Directory of flash:
……
9 -rw-236011 May 23 2020 14:56:45 diag_H3C_20200523-151204.tar.gz
3710740 KB total (2508852 KB free)
# To display operating statistics on the monitor terminal, enter nat the prompt. (Operating
statistics vary by software version.)
Save or display diagnostic information (Y=save, N=display)? [Y/N] :N
===============================================
===============display clock===============
10:27:16 UTC Wed 05/23/2020
=================================================
===============display version===============
H3C Comware Software, Version 7.1.070, Release
7595
Copyright (c) 2004-
2020 New H3C Technologies Co., Ltd. All rights reserved.
H3C S12508G-AF uptime is 0 weeks
, 1 day, 6 hours, 23 minutes
Last reboot reason : USER reboot
Boot image: flash:/S12500G-CMW710-BOOT-E7595.bin
Boot image version: 7.1.070, Release 7595
Compiled May 19 2020 11:00:00
System image: flash:/S12500G-CMW710-SYSTEM-E7595.bin
System image version: 7.1.070, Release 7595
Compiled May 19 2020 11:00:00
Feature image(s) list:
flash:/S12500G-CMW710-DEVKIT-E7595.bin, version: 7.1.070, Release 7595
Compiled May 19 2020 11:00:00

7
flash:/S12500G-CMW710-FREERADIUS-E7595.bin, version: 7.1.070, Release 7595
Compiled May 19 2020 11:00:00
Patch image(s) list:
flash:/S12500G-CMW710-SYSTEM-E7595H01.bin, version: 7.1.070
Compiled May 19 2020 11:00:00
MPU(M) 0:
Uptime is 0 weeks,1 days,8 hours,41 minutes
BOARD TYPE: LSXM2SUPT2
DRAM: 16384M bytes
FLASH: 3630M bytes
NVRAM: 512K bytes
PCB 1 Version: VER.A
PCB 2 Version: VER.A
PCB 3 Version: VER.A
PCB 4 Version: VER.B
Basic BootWare Version: 107
Extended BootWare Version: 302
CPLD 1 Version: 002
CPLD 2 Version: 002
CPLD 3 Version: 002
CPLD 4 Version: 002
PowChip Version: NONE
PLL Version: None
Release Version: H3C S12516G-AF-7595
Patch Version: None
Reboot Cause: UserReboot
MPU(S) 1:
Uptime is 0 weeks,1 days,8 hours,41 minutes
BOARD TYPE: LSXM2SUPT2
DRAM: 16384M bytes
FLASH: 3630M bytes
NVRAM: 512K bytes
PCB 1 Version: VER.A
PCB 2 Version: VER.A
PCB 3 Version: VER.A
PCB 4 Version: VER.B
Basic BootWare Version: 107
Extended BootWare Version: 302
CPLD 1 Version: 002
CPLD 2 Version: 002
CPLD 3 Version: 002
CPLD 4 Version: 002
PowChip Version: NONE
PLL Version: None
Release Version: H3C S12516G-AF-7595

8
Patch Version: None
Reboot Cause: UserReboot
LPU 3:
Uptime is 0 weeks,1 day,8 hours,51 minutes
BOARD TYPE: LSXM1CGQ36TE2
DRAM: 8192M bytes
FLASH: 0M bytes
NVRAM: 0K bytes
PCB 1 Version: VER.A
PCB 2 Version: VER.A
PCB 3 Version: VER.A
PCB 4 Version: VER.A
Basic BootWare Version: 100
Extended Bootrom Version: 100
CPLD 1 Version: 001
CPLD 2 Version: 001
CPLD 3 Version: 002
FPGA 1 Version: 006
Power CPLD Version: 007
PowChip Version: NONE
PLL Version: None
PCIE 1 Version: 001
PCIE 2 Version: 001
PCIE 3 Version: 001
PCIE 4 Version: 001
Release Version: H3C S12516G-AF-7595
Patch Version: None
Reboot Cause: UserReboot
NPU 18:
Uptime is 0 weeks,1 day,8 hours,51 minutes
BOARD TYPE: LSXM1SFT16F2
DRAM: 8192M bytes
FLASH: 0M bytes
NVRAM: 0K bytes
PCB 1 Version: VER.A
PCB 2 Version: VER.B
PCB 3 Version: VER.A
Basic BootWare Version: 100
Extended Bootrom Version: 100
CPLD 1 Version: 001
CPLD 2 Version: 002
PowChip Version: NONE
PLL Version: None
Release Version: H3C S12516G-AF-7595
Patch Version: None
Reboot Cause: UserReboot

9
……
Contacting technical support
If an issue persists after you perform the troubleshooting procedures in this document, contact H3C
Support. When you contact an authorized H3C support representative, be prepared to provide the
following information:
•
Information described in "General guidelines."
•
Product serial numbers.
This information will help the support engineer assist you as quickly as possible.
You can contact H3C Support at mailto:[e-mail].

10
Removing deployment errors
Use the deployment checklist in Table 2 to eliminate issues that might be introduced at the
deployment stage. Select items that are suitable for your site.
Table 2 Deployment checklist
Question
Command or method
Result
Remarks
Environment and card hardware status
Is the switch temperature
20°C (68°F) lower than the
warning temperature
threshold?
display environment
□OK
□Not OK
□Not related
Make sure the temperature
of the switch is 20°C (68°F)
lower than
the warning
temperature threshold.
Are the fan trays operating
correctly? display fan
□OK
□Not OK
□Not related
Make sure the fan trays are
operating correctly.
Are sufficient power
supplies installed
and are
they operating correctly? display power
□OK
□Not OK
□Not related
Make sure the following
conditions are met:
•
You have installed
sufficient power
suppl
ies to provide
power redundancy.
•
The power supplies
are operating
correctly. The
display power
command shows that
their state is Normal.
Are the LEDs all displaying
correct statuses? Visually check the RUN LED and alarm LED on each card
□OK
□Not OK
□Not related
Verify that the RUN LED
flashes slowly, and the
alarm LED is off.
Are all cards operating
correctly? display device
□OK
□Not OK
□Not related
Make sure all cards are
operating correctly.
•All service cards are in
Normal state.
•T
he active MPU is in
Master state.
•
The standby MPUs
are in
Standby
state.
Active and standby MPUs
Are the software versions
of the active and standby
MPUs the same? display boot-loader
□OK
□Not OK
□Not related
Make sure the software
versions of the active and
standby MPUs are the
same.
Do the standby MPUs
have a startup
configuration file? dir
□OK
□Not OK
□Not related
If any standby MPUs do not
have a startup
configuration file, execute
the save command without
specifying any parameters.
This command enables
you to save the running
configuration to a

11
Question
Command or method
Result
Remarks
configuration file and
specifies the file as the
next-
startup configuration
file on each MPU.
CPU and memory usage
Does the CPU usage
change rate of any cards
(MPUs and LPUs) exceed
10%? Does the sustained
CPU usage exceed 60%?
display cpu-usage
□OK
□Not OK
□Not related
Execute the
display
cpu-usage command
repeatedly.
If the CPU of a card
sustains a usage level of
over 60% or has a change
rate higher than 10%,
execute the debug
ip
packet command to view
the packets delivered to the
CPU for analysis.
Does the memory usage of
the MPUs and service
modules exceed 60%? display memory
□OK
□Not OK
□Not related
If memory usa
ge exceeds
60%, execute the
display
system internal
kernel memory pool
slot command
in probe
view to identify the module
that is using the most
memory.
Ports
Is there a port operating in
half-duplex mode?
display interface
brief
□OK
□Not OK
□Not related
If there is a port operating
in half-
duplex mode,
identify
whether the two
ends are consistent in
configuration.
Is flow control
unnecessarily enabled on
ports?
display
current-configuration
interface
□OK
□Not OK
□Not related
Execute the
undo
flow-control command
if flow control is not needed
on a port.
Are large numbers of error
packets generated
continuously in the
outbound or inbound
direction of the port?
display interface
□OK
□Not OK
□Not related
If an error counter displays
a non-zero value and the
value is increasing, check
for the following errors:
•
Link and
optical-electrical
converter errors.
•
Port setting
inconsistencies with
the peer port.
Does the port change
between an up and down
state frequently? display logbuffer
□OK
□Not OK
□Not related
If the port state flaps, check
for the following errors:
•L
ink and
optical-electrical
converter errors.
•
Optical power
threshold crossing
events if the port is a
fiber port.
•
Port setting
inconsistencies with

12
Question
Command or method
Result
Remarks
the peer port.
Fiber ports
Do the ports at the two
ends use the same port
settings?
display
current-configuration
interface
□OK
□Not OK
□Not related
To connect an H3C device
to a device from another
vendor, set the same port
rate and duplex mode
settings at the two ends as
a best practice.
Are CRC errors present on
any fiber port? Is the
number of CRC errors
increasing?
display interface
□OK
□Not OK
□Not related
If CRC errors persist,
replace the transceiver
module or pigtail fiber, or
clean the transceiver
module connector.
Trunk port configuration
Do the peer trunk ports use
the same PVID?
display
current-configuration
interface
□OK
□Not OK
□Not related
Make sure the same PVID
is configured on the trunk
ports between two devices.
Are the
peer ports
assigned to the same
VLANs?
display
current-configuration
interface
□OK
□Not OK
□Not related
Make sure the trunk ports
between two devices are
assigned to the same
VLANs.
For example, if you assign
a trunk port to all VLANs,
also assign its peer port to
all VLANs.
Are the peer ports set to
the same link type?
display
current-configuration
interface
□OK
□Not OK
□Not related
Make sure the ports
between
two devices use
the same link type.
Is a loop present in VLAN
1? loopback-detection
global enable vlan 1
□OK
□Not OK
□Not related
Remove ports from VLAN 1
as needed.
Spanning tree feature
Is the
timeout factor
correctly set? display
current-configuration
□OK
□Not OK
□Not related
As a best practice to avoid
unnecessary
recalculations
, set a
timeout factor in the range
of 5 to 7 on
a stable
network.
Are ports connected to
end-
user devices
configured as edge ports?
display
current-configuration
interface
□OK
□Not OK
□Not related
Verify that the output from
the
display
current-configuratio
n interface command
contains the "
stp
edged-port enable"
string for ports connected
to end-user devices.
As a best practice,
configure ports connected
to end-user devices (PCs,
for example) as edge ports,
or disable the spanning

13
Question
Command or method
Result
Remarks
tree feature on the ports.
Is the device running
MSTP, STP, or RSTP, and
working with a Cisco
PVST+ device?
display stp
□OK
□Not OK
□Not related
As a best practice to avoid
interoperability issues, set
up a Layer 3 connection to
the Cisco device.
Do the topologies of MSTIs
meet the design?
Are there as few
overlapping paths as
possible among MSTIs?
display
current-configuration
interface
□OK
□Not OK
□Not related
If the topologies deviate
from the design, reassign
ports to VLANs and revise
the
VLAN and instance
mappings.
For optimal load balancing,
plan VLANs and
VLAN-to-instance
mapping
s to minimize
overlapping paths among
different MSTIs.
Does a TC
attack exist to
cause frequent STP status
changes on any ports?
display stp tc
display stp history
□OK
□Not OK
□Not related
Examine the following
items in the command
output for TC attacks:
•
Incoming and
outgoing TC/TCN
BPDU statistics.
•H
istorical port role
calculation
information.
There is a risk of TC attack
if frequent STP status
changes occur on a stable
network.
Make sure
you have
configured
the following
settings:
•Configure ports
connected to end-user
devices as edge ports,
and enable BPDU
guard. Alternatively,
disable the spanning
tree feature on the
ports.
•
Disable the spanning
tree feature on ports
connected to devices
that do not support
spanning tree
protocols.
•Do not disable
TC-BPDU guard.
VRRP
Is the handshake interval
correctly set?
Are the handshake
intervals of the two ends
the same?
display vrrp
□OK
□Not OK
□Not related
Change the handshake
interval to 3 seconds if the
number of VRRP groups is
smaller than 5.
If five or more VRRP
groups exist, assign three
or five VRRP groups to one
group, and configure the

14
Question
Command or method
Result
Remarks
handshake interval as 3
seconds, 5 seconds, and 7
seconds for the groups,
respectively.
ARP
Are there ARP conflicts? display logbuffer
□OK
□Not OK
□Not related
If the log contains ARP
conflict records, verify that
the hosts in conflict are
legitimate, and remove the
conflicts.
OSPF
Is the router ID of the
device unique on the
network? display ospf peer
□OK
□Not OK
□Not related
Change the router ID if it is
not unique on the network.
T
o restart route learning
after you remove the router
ID conflict, you must
execute the r
eset ospf
process
command.
Are there a lot of errors in
the output from the
d
isplay ospf
statistics error
command?
display ospf
statistics error
□OK
□Not OK
□Not related
If a large number of OSPF
errors has occur
red and
the number
continues to
increase,
collect the error
information
for further
analysis.
Are there severe route
flappings?
display ip
routing-table
statistics
□OK
□Not OK
□Not related
Examine the statistics for
added and
deleted routes
during the system uptime.
If route flapping occurs,
locate the flapping route
and the source device to
analyze the cause. You
can use the display
ospf lsdb command
multiple times to view the
age of routes and locate
the flapping route.
Is the OSPF status stable? display ospf peer
□OK
□Not OK
□Not related
View the up time of the
OSPF neighbor.
Routes
Is the default route
correct?
Are there any routing
loops?
tracert
debug ip packet
□OK
□Not OK
□Not related
Use the tracert
command to trace the path
to a nonexistent network
(1.1.1.1
, for example) to
check for routing loops. If a
routing loop exists, check
the configuration of the
involved devices for errors.
Adjust the route to remove
the loop.
Use the debug ip packet
command to check for

15
Question
Command or method
Result
Remarks
packets with TTL 0 or 1. If
TTL exceeded packets are
received, check for network
route errors.
CPU security
Are there packet attacks
on the CPU? debug rxtx softcar show
□OK
□Not OK
□Not related
Execute the
debug rxtx
softcar show command
in probe view to view
packet rate limit
information for cards.
The CPU is under attack if
the number of packets of a
type keeps increasing
unusually.

16
Dealing with password loss
Dealing with console login password loss
Use either of the following methods:
•
(Preferred.) Telnetting to the device to change the console login password
•
Using BootWare menus to change the console login password
Telnetting to the device to change the console login
password
Before you Telnet to the device, make sure the following requirements are met:
•
You can log in to the device by using Telnet.
•
After login, you are assigned the user role network-admin or level-15.
To Telnet to the device to change the console login password:
1. Telnet to the device. (Details not shown.)
2. Determine the user line you are using.
<Sysname> display users
Idx Line Idle Time Pid Type
1 AUX 1/1 00:00:36 Jun 14 16:35:09 543
+ 16 VTY 0 00:00:00 Jun 14 17:02:03 566 TEL
Following are more details.
VTY 0 :
Location: 192.168.29.1
+ : Current operation user.
F : Current operation user works in async mode.
The output shows that two users are online. You are using VTY 0. Your IP address is
192.168.29.1. The other user is using AUX 1/1.
3. Display the user roles assigned to the user line you are using.
[Sysname] line vty 0
[Sysname-line-vty0] display this
#
line aux 1/1
user-role network-operator
#
line vty 0
authentication-mode none
user-role level-15
user-role network-admin
user-role network-operator
#
return
The output shows that VTY 0 has the user role level-15. You have the right to change the
console login password.