(Optional) Setting Interface Parameters

This section describes how to set parameters for an interface based on the actual service requirements. The parameters include the description and maximum transmission unit (MTU).

Context

Table 1 describes the configurable parameters of an interface.

**Table 1** Configurable parameters of an interface
Parameter	Description
Interface description	When you maintain a large number of interfaces, an interface description helps identify an interface easily.
Interface MTU	After the MTU is configured for an interface, the device fragments a packet transmitted on the interface if the size of the packet exceeds the MTU. NOTE: Loopback and NULL interfaces do not support the MTU.
Interface bandwidth that can be obtained by the NMS through the MIB	You can calculate the bandwidth usage by setting the interface bandwidth that can be obtained by the NMS through the MIB.
Whether the device sends a trap message to the NMS when the interface status changes	You can enable the device to send a trap message to the NMS when the interface status changes. After this function is enabled, the NMS monitors the interface status in real time. However, if an interface alternates between up and down, the device will frequently send trap messages to the NMS, which increases the processing load on the NMS. In this situation, you can disable the device from sending trap messages to the NMS to avoid adverse impact on the NMS.
Interval at which traffic statistics are collected	After setting the interval at which traffic statistics are collected for an interface, you can view the traffic volumes and rates of the interface in different time ranges.
Whether the control-flap function is enabled	Control-flap controls the frequency of interface status alternations between up and down, which minimizes the impact on device and network stability. NOTE: Loopback and NULL interfaces do not support the control-flap function.

Procedure

Run system-view
The system view is displayed.
Run interface interface-type interface-number
The interface view is displayed.

In this command, interface-type specifies the type of the interface, and interface-number specifies the number of the interface.

Perform one or more operations in Table 2 to set the desired interface parameters.

**Table 2** Setting interface parameters
Operation	Description
Configure a description for an interface.	Run the description regular-expression command to configure a description for an interface. You can view the description of an interface using the following commands: display interface description [ interface-type [ interface-number ] \| slot slot-id [ card card-number ] ] display ip interface description [ interface-type [ interface-number ] \| interface-name \| slot slot-number [ card card-number ] \| ip-configured [ except interface-type ] ] display ipv6 interface description [ interface-type [ interface-number ] \| interface-name \| slot slot-id [ card card-number ] ] NOTE: The parameters slot slot-id and card card-number in the preceding commands are supported only on the Admin VS in VS mode.
Set an MTU for an interface.	Run the mtu mtu or ipv6 mtu mtu command to set an MTU for an interface. Run the mtu mtu spread or ipv6 mtu mtu spread command to set an MTU for an interface and apply the MTU to all the sub-interfaces on the interface. NOTE: After changing the MTU on a interface using the mtu or mtu spread command, run the shutdown and undo shutdown commands in the interface view for the change to take effect. Alternatively, you can run the restart command in the interface view to restart the interface for the change to take effect. If IPv4 attributes are configured on an interface, run the mtu or mtu spread command to set an MTU for the IPv4 packets to be sent by the interface. If IPv6 attributes are configured on an interface, run the ipv6 mtu or ipv6 mtu spread command to set an MTU for the IPv6 packets to be sent by the interface.
Set configuration bandwidth for an interface.	Run the bandwidth command to set configuration bandwidth for an interface. NOTE: To view the command configurations, you can check the ifSpeed and ifHighSpeed objects in the IF-MIB on the NMS.
Configure whether the device sends a trap message to the NMS when the interface status changes.	Run the enable snmp trap updown command to enable the device to send a trap message to the NMS when the interface status changes. NOTE: If an interface alternates between up and down, the device will frequently send trap messages to the NMS, which increases the processing load on the NMS. In this situation, you can run the undo enable snmp trap updown command to disable the device from sending trap messages to the NMS to avoid adverse impact on the NMS.
Set the interval at which traffic statistics are collected.	Run the set flow-stat interval interval command to set the interval at which traffic statistics are collected. NOTE: To set a global interval at which traffic statistics are collected, run the set flow-stat interval interval command in the system view, and you do not need to run the interface interface-type interface-number command. The global interval applies to all interfaces for which the interval at which traffic statistics are collected is not set. The new interval takes effect after the original interval expires. For a logical interface, traffic statistics will be updated since the second statistical cycle of the new interval. For a physical interface, traffic statistics are updated immediately after the new interval takes effect.
Enable the control-flap function.	Run the control-flap [ suppress reuse ceiling decay-ok decay-ng ] command to enable the control-flap function on an interface. The value of suppress is 1000 times the interface suppression threshold. It ranges from 1 to 20000. The default value is 2000. The value of suppress must be greater than the value of reuse and less than the value of ceiling. The value of reuse is 1000 times the interface reuse threshold. It ranges from 1 to 20000. The default value is 750. The value of reuse must be less than the value of suppress. The value of ceiling is 1000 times the maximum interface suppression penalty value. It ranges from 1001 to 20000. The default value is 6000. The value of ceiling must be greater than the value of suppress. decay-ok specifies the half life for the penalty value when an interface is up. It ranges from 1 to 900, in seconds. The default value is 54. decay-ng specifies the half life for the penalty value when an interface is down. It ranges from 1 to 900, in seconds. The default value is 54.

Run commit
The configuration is committed.