Contents

Configuring fast log output 1

About fast log output 1

Restrictions and guidelines: fast log output configuration·· 1

Procedure· 2

Fast log output configuration examples· 2

Example: Configuring fast log output to a log host 2

Configuring fast log output

About fast log output

The fast log output feature enables fast output of logs to log hosts.

Typically, logs generated by a service module are first sent to the information center, which then outputs the logs to the specified destination (such as to log hosts). When fast log output is configured, logs of service modules are sent directly to log hosts instead of to the information center. Compared to outputting logs to the information center, fast log output saves system resources. For more information about the information center, see "Configuring the information center."

Logs are classified into eight severity levels from 0 through 7 in descending order.

Table 1 Log levels

Restrictions and guidelines: fast log output configuration

The device supports outputting logs from service modules to log hosts by using the following methods in descending order of priority:

1.        Fast log output. Only NAT logs can be output by using this method in the current software version. For more information about NAT logs, see NAT Configuration Guide.

2.        Flow log. For more information about flow log and the service modules supported by flow log, see "Configuring flow log."

3.        Information center.

If you configure multiple log output methods for a service module, the service module outputs its logs in the method that has the highest priority.

To output NAT logs to a log host, you must specify the log format required by the log host in the customlog format and customlog host commands.

Procedure

1.        Enter system view.

system-view

2.        Enable fast log output.

customlog format { cmcc | telecom | unicom }

By default, fast log output is disabled.

3.        Configure fast log output parameters.

customlog host [ vpn-instance vpn-instance-name ] { hostname | ipv4-address | ipv6 ipv6-address } [ port port-number ] export { cmcc-sessionlog | cmcc-userlog | telecom-sessionlog | telecom-userlog | unicom-sessionlog | unicom-userlog } * [ sysname sysname ]

By default, no fast log output parameters are configured.

The value for the port-number argument must be the same as the port number configured on the log host. Otherwise, the log host cannot receive logs.

4.        (Optional.) Specify the source IP address for fast log output.

customlog host source interface-type interface-number

By default, the source IP address of fast output logs is the primary IP address of the outgoing interface.

If this command is configured, the primary IP address of the specified interface is used as the source IP address of fast output logs regardless of the outgoing interface.

Configure this command when you need to filter logs by source IP address on the log host.

5.        (Optional.) Configure the timestamp of fast output logs to show the system time.

customlog timestamp localtime

By default, the timestamp of fast output logs shows the Greenwich Mean Time (GMT).

Fast log output configuration examples

Example: Configuring fast log output to a log host

Network configuration

As shown in Figure 1, configure fast log output on the device to send NAT444 user logs to the log host in CMCC format.

Figure 1 Network diagram

Procedure

1.        Make sure the device and the log host can reach each other. (Details not shown.)

2.        Configure the device:

# Enable fast log output in CMCC format.

<Device> system-view

[Device] customlog format cmcc

# Output NAT444 user logs in CMCC format to the log host at 1.2.0.1/16.

[Device] customlog host 1.2.0.1 port 1000 export cmcc-userlog

# Enable NAT444 user log.

[Device] nat log enable

[Device] nat log port-block-assign

[Device] nat log port-block-withdraw

3.        Configure the log host:

The log host configuration varies by log host. For more information, see related document of the log host.