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ME60 Troubleshooting Guide V2.0 (VRPv8)

This document provides the maintenance guide of the device, including daily maintenance, emergence maintenance, and typical troubleshooting.

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NAT Troubleshooting

NAT Troubleshooting

This section describes how to locate and troubleshoot common NAT faults.

NAT Network IP Address Translation Failures

This section provides the flowchart and procedure for troubleshooting NAT network IP address translation failures.

Common Causes

Common causes are as follows:
  • NAT configuration is incorrect. As a result, sessions fail to be set up.

  • The NAT gateway fails to connect to an external host as no route is configured for the NAT gateway.

  • An ACL is configured incorrectly.

  • An internal host fails to connect to the NAT gateway.

  • ALG is disabled.

Fault Locating Flowchart

To rectify the fault, follow the troubleshooting flowchart shown in Figure 4-121.

Figure 4-121 Troubleshooting NAT network IP address translation failures

Troubleshooting Procedure



Saving the results of each troubleshooting step is recommended. If your troubleshooting fails to correct the fault, you will have a record of your actions to provide Huawei technical support personnel.


  1. Check whether information about NAT sessions is correct.

    Run the display nat session table slot slot-id [ engine engine-id | card card-id ] command and check whether NAT session information is correct. For example:

    <HUAWEI> display nat session table slot 1 engine 0
    This operation will take a few minutes. Press 'Ctrl+C' to break ...
    Slot: 1 Engine: 0
    Current total sessions: 1.
    • If a protocol, IP address, or port number in the command output is incorrect, check NAT configurations. If there are incorrect NAT parameters, reconfigure them.

      For information about how to configure NAT services, see Configuring Basic NAT Functions in HUAWEI ME60 Configuration Guide - NAT and IPv6 Transition Technologies.

    • If the protocol, IP address, and port number in the command output are correct, go to 2.

  2. Check whether a NAT device is correctly connected to an external destination host.

    Run the ping command on the NAT device to ping the external destination host.

    • If the ping fails, perform the following operations:

      1. Run the display ip routing-table command to view routing table information. Check whether a NAT device has a reachable route to the external destination host. If the route is unreachable, reconfigure a route as needed:
        • Configure a static route on the NAT server if the following conditions are met:
          • The address of the external destination host is on a different segment from that of the external network interface on the NAT device.
          • No corresponding route is configured on the NAT device.
          After the static route is configured, an intranet packet can then be forwarded through the static route after being processed on the NAT device.
        • A static route does not need to be configured on the NAT device if the IP address of the external destination host is on the same segment as that of the external network interface on the NAT device.

      2. Check whether the IP address of the external network interface on the NAT device conflicts with that of the external destination host. If the two IP addresses conflict, re-configure a NAT address pool.

    • If the NAT device can ping the external host, go to 3.

  3. Check whether a route is correctly configured for an intranet host.

    Run the display ip routing-table command to check whether a correct route is configured for the intranet host.

    • If the route to the intranet host is unreachable, reconfigure the route.

    • If the route to the intranet host is reachable, go to 4.

  4. Contact Huawei and provide the following information:

    • Results of this troubleshooting procedure

    • Configuration, log, and alarm files

Relevant Alarms and Logs

Relevant Alarms

NAT_1. hwCGNGloablV4SessionNumAlarm

NAT_1. hwCGNGloablV4SessionNumResumeAlarm

NAT_1. hwCGNUserPortNumAlarm

NAT_1. hwCGNPortUsageOfSpecificIpPreAlarm


NAT_1. hwCGNSessionExhaustResumeAlarm

NAT_1. hwCGNSpecificIpExhaustAlarm

NAT_1. hwCGNNoPatAddrGroupExhaustAlarm

NAT_1. hwCGNNoPatAddrGroupExhaustResumeAlarm

NAT_1. hwCGNNoPatAddrGroupThresholdAlarm

NAT_1. hwCGNNoPatAddrGroupThresholdResumeAlarm

NAT_1. hwCGNUserTableExhaustAlarm

NAT_1. hwCGNUserTableExhaustResumeAlarm

NAT_1. hwCGNUserTableThresholdAlarm

NAT_1. hwCGNUserTableThresholdResumeAlarm

Relevant Logs

















Updated: 2019-11-20

Document ID: EDOC1000175918

Views: 26849

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