Troubleshoot without overturning | A collection of troubleshooting commands that network engineers must collect

Network engineers need to master a variety of network troubleshooting methods.

to ensure network stability and availability.

The following are 30 commonly used troubleshooting commands

Comes with detailed instructions and some command examples for Huawei network equipment

To help novice network engineers better understand:

1. 1. Ping test：

   • • Method: Use theping command to test the connectivity of the target device.

   • • Command: Enter the following command in the command line interface:

     Ping the IP address or domain name of the target device

   • • Example: (Assume the target IP address is 10.0.0.1)

     <Huawei Equipment> ping 10.0.0.1

2. 2. Traceroute/Tracepath：

   • • Method: Use the tracert command (Windows) or traceroute command (Linux) to view the routing path of the data packet.

   • • Command: Enter the following command in the command line interface:

     tracert IP address or domain name of the target device

   • • Example:

     <Huawei Equipment> tracert 10.0.0.1

3. 3. Telnet/SSH remote login:

   • • Method: Use Telnet or SSH protocol to remotely connect to the target device to view and manage the device.

   • • Command (SSH): Enter the following command in the command line interface:

     ssh username@IP address or domain name of the target device

   • • Example: (Assume the user name is admin and the target IP address is 10.0.0.1)

     <Huawei Equipment> ssh [email protected]

4. 4. Packet capture analysis:

   • • Method: Use packet capture tools such as Wireshark to capture and analyze network data packets.

   • • Command: Download and install Wireshark, then run the application and select the network interface to start capturing packets.

   • • No specific commands, use graphical interface tools such as Wireshark.

5. 5. Check the physical connection:

   • • Method: Check the physical connections to make sure cables, plugs, and ports are all connected.

   • • Example: Check the indicator lights on the device panel to ensure that the port status is normal.

6. 6. Check routing table and ARP table:

   • • Method: Check the routing table and ARP table on the router.

   • • Command (routing table): Enter the following command in the command line interface:

     display ip routing-table

   • • Command (ARP table): Enter the following command in the command line interface:

     display arp

   • • Example:

     <Huawei Equipment> display ip routing-table
     <Huawei Equipment> display arp

7. 7. Log analysis:

   • • Method: View log files on the device and server for errors or exceptions related to network issues.

   • • Example: Use the command to view the log files on the device.

     <Huawei equipment> display logbuffer

8. 8. Port and service check:

   • • Method: Confirm whether the device's port and service configuration are correct, including firewall rules and ACLs.

   • • Example: View the device's port configuration and firewall rules.

     <Huawei Equipment> display current-configuration | include port-group
     <Huawei Equipment> display firewall configuration

9. 9. Performance monitoring:

   • • Method: Use monitoring tools (such as eSight) to monitor the performance of network devices and services.

   • • No specific commands, use monitoring tools to monitor performance.

10. 10. Updates and backups:

    • • Method: Regularly update device firmware and backup configurations to prevent failures and data loss.

    • • Example: Perform backup and update operations.

      <Huawei Equipment> save
      <Huawei Equipment> upgrade software filename.bin

11. 11. DNS query:

    • • Method: Use theping command to test whether the DNS resolution is correct.

    • • Example: Useping to test domain name resolution.

      <Huawei Equipment> ping www.example.com

12. 12. Firewall rule check:

    • • Method: Check the firewall rule configuration to ensure that necessary traffic is allowed to pass.

    • • Example: View firewall rules.

      <Huawei Equipment> display firewall zone
      <Huawei Equipment> display firewall rule

13. 13. VLAN configuration check:

    • • Method: Check the VLAN configuration on the switch to make sure the device is in the correct VLAN.

    • • Example: View VLAN configuration.

      <Huawei equipment> display vlan

14. 14. MTU size check:

    • • Method: Check the maximum transmission unit (MTU) settings of your network devices and make sure they match.

    • • Example: View interface MTU configuration.

      <Huawei Equipment> display interface GigabitEthernet0/0/1

15. 15. Load balancing configuration check:

    • • Method: Check the configuration of the load balancing device to ensure even distribution of traffic.

    • • Example: View server farm configuration.

      <Huawei Equipment> display server-farm

16. 16. BGP neighbor status check:

    • • Method: Check the BGP neighbor status to ensure that BGP routes are propagated normally.

    • • Example: View BGP neighbor status.

      <Huawei equipment> display bgp peer

17. 17. SNMP monitoring:

    • • Method: Use SNMP protocol to monitor device performance and status.

    • • No specific commands, configure the SNMP agent and use SNMP management tools to monitor the device.

18. 18. Traffic analysis:

    • • Method: Use a traffic analysis tool such as NetFlow or sFlow to monitor traffic patterns and bandwidth usage. - No specific commands, configure the traffic analysis tool and analyze the data.

19. 19. Subnet mask check:

    • • Method: Check whether the subnet mask is configured correctly to ensure that the IP address is assigned correctly.

    • • Example: View interface configuration.

      <Huawei Equipment> display ip interface GigabitEthernet0/0/1

20. 20. MTU Path Discovery：

    • • Method: Use MTU Path Discovery to check the maximum transmission unit of a network path.

    • • Example: Enable MTU Path Discovery.

      <Huawei Equipment> system-view
      [Huawei Equipment] ip mtu discovery

21. 21. ACL rule check:

    • • Method: Check access control list (ACL) rules to ensure the correct traffic is allowed or blocked.

    • • Example: View ACL rules.

      <Huawei Equipment> display acl 2000

22. 22 DHCP allocation check:

    • • Method: Check the IP address assigned by the DHCP server to ensure it is configured correctly.

    • • Example: View DHCP allocation information.

      <Huawei equipment> display dhcp server ip-in-use

23. 23. Link aggregation check:

    • • Method: Check the link aggregation group (LAG) configuration to ensure that link balancing is normal.

    • • Example: View LAG configuration.

      <Huawei Equipment> display link-aggregation verbose

24. 24. MAC address table check:

    • • Method: Check the MAC address table of the switch to ensure that the MAC address is distributed correctly.

    • • Example: View MAC address table.

      <Huawei equipment> display mac-address

25. 25. System resource utilization monitoring:

    • • Method: Monitor the utilization of system resources such as CPU, memory and storage.

    • • Example: View system resource utilization.

      <Huawei Equipment> display resource usage

26. 26. ACL log analysis:

    • • Method: Check the ACL rule matching log to check whether any traffic is blocked by the ACL.

    • • Example: View ACL logs.

      <Huawei equipment> display acl log

27. 27. Link status check:

    • • Method: Check the link status and confirm whether the link is connected normally.

    • • Example: View link status.

      <Huawei equipment> display interface brief

28. 28. DNS server availability check:

    • • Method: Use thenslookup command to check the availability of the DNS server.

    • • Example: Testing DNS server availability.

      <Huawei Equipment> ping dns-server-ip

29. 29. OSPF neighbor status check:

    • • Method: Check the OSPF neighbor status to ensure that the routing protocol is working properly.

    • • Example: View OSPF neighbor status.

      <Huawei equipment> display ospf peer

30. 30. Redundant routing and HA status check:

    • • Method: Check redundant routing and high availability (HA) configuration to ensure backup equipment is functioning properly.

    • • Example: View HA status.

      <Huawei equipment> display standby