Contents

Configuring Ethernet interfaces· 1

About Ethernet interface· 1

Configuring common Ethernet interface settings· 1

Configuring basic settings of an Ethernet interface· 1

Configuring jumbo frame support 2

Configuring dampening on an Ethernet interface· 2

Setting the statistics polling interval 4

Restoring the default settings for an interface· 4

Display and maintenance commands· 4

 

 

Configuring Ethernet interfaces

About Ethernet interface

The device supports Layer 2 Ethernet interfaces. They are physical Ethernet interfaces operating at the data link layer (Layer 2) to switch packets.

This chapter describes how to configure Ethernet interfaces.

 

Configuring common Ethernet interface settings

Configuring basic settings of an Ethernet interface

About this task

You can configure an Ethernet interface to operate in auto duplex mode. In this mode, the interface negotiates a duplex mode with its peer.

You can set the speed of an Ethernet interface or enable it to automatically negotiate a speed with its peer.

Procedure

1.     Enter system view.

system-view

2.     Enter Ethernet interface view.

interface interface-type interface-number

3.     Set the description for the Ethernet interface.

description text

The default setting is interface-name Interface. For example, GigabitEthernet1/0/2 Interface.

4.     Set the duplex mode for the Ethernet interface.

duplex auto

Support for this command varies by device model. For more information, see Interface Command Reference.

By default, the duplex mode is auto for Ethernet interfaces.

5.     Set the speed for the Ethernet interface.

speed { 1000 | auto }

By default, the speed is auto for Ethernet interfaces.

6.     Set the expected bandwidth for the Ethernet interface.

bandwidth bandwidth-value

By default, the expected bandwidth (in kbps) is the interface baud rate divided by 1000.

7.     Bring up the Ethernet interface.

undo shutdown

By default, an Ethernet interface is up.

Configuring jumbo frame support

About this task

Jumbo frames are frames larger than a device-specific size and are typically received by an Ethernet interface during high-throughput data exchanges, such as file transfers.

The Ethernet interface processes jumbo frames in the following ways:

·     When the Ethernet interface is configured to deny jumbo frames (by using the undo jumboframe enable command), the Ethernet interface discards jumbo frames.

·     When the Ethernet interface is configured with jumbo frame support, the Ethernet interface performs the following operations:

¡     Processes jumbo frames within the specified length.

¡     Discards jumbo frames that exceed the specified length.

Procedure

1.     Enter system view.

system-view

2.     Enter Ethernet interface view.

interface interface-type interface-number

3.     Configure jumbo frame support.

jumboframe enable [ size ]

By default, The device allows jumbo frames within 1522 bytes to pass through GE interfaces and jumbo frames within 3072 bytes to pass through 10-GE interfaces.

Configuring dampening on an Ethernet interface

About this task

The interface dampening feature uses an exponential decay mechanism to prevent excessive interface flapping events from adversely affecting routing protocols and routing tables in the network. Suppressing interface state change events protects the system resources.

If an interface is not dampened, its state changes are reported. For each state change, the system also generates an SNMP trap and log message.

After a flapping interface is dampened, it does not report its state changes to the CPU. For state change events, the interface only generates SNMP trap and log messages.

Parameters

·     Penalty—The interface has an initial penalty of 0. When the interface flaps, the penalty increases by 1000 for each down event until the ceiling is reached. It does not increase for up events. When the interface stops flapping, the penalty decreases by half each time the half-life timer expires until the penalty drops to the reuse threshold.

·     Ceiling—The penalty stops increasing when it reaches the ceiling.

·     Suppress-limit—The accumulated penalty that triggers the device to dampen the interface. In dampened state, the interface does not report its state changes to the CPU. For state change events, the interface only generates SNMP traps and log messages.

·     Reuse-limit—When the accumulated penalty decreases to this reuse threshold, the interface is not dampened. Interface state changes are reported to the upper layers. For each state change, the system also generates an SNMP trap and log message.

·     Decay—The amount of time (in seconds) after which a penalty is decreased.

·     Max-suppress-time—The maximum amount of time the interface can be dampened. If the penalty is still higher than the reuse threshold when this timer expires, the penalty stops increasing for down events. The penalty starts to decrease until it drops below the reuse threshold.

When configuring the dampening command, follow these rules to set the values mentioned above:

·     The ceiling is equal to 2(Max-suppress-time/Decay)  × reuse-limit. It is not user configurable.

·     The configured suppress limit is lower than or equal to the ceiling.

·     The ceiling is lower than or equal to the maximum suppress limit supported.

Figure 1 shows the change rule of the penalty value. The lines t0 and t2 indicate the start time and end time of the suppression, respectively. The period from t0 to t2 indicates the suppression period, t0 to t1 indicates the max-suppress-time, and t1 to t2 indicates the complete decay period.

Figure 1 Change rule of the penalty value

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Restrictions and guidelines

·     The dampening command does not take effect on the administratively down events. When you execute the shutdown command, the penalty restores to 0, and the interface reports the down event to the upper-layer protocols.

Procedure

1.     Enter system view.

system-view

2.     Enter Ethernet interface view.

interface interface-type interface-number

3.     Enable dampening on the interface.

dampening [ half-life reuse suppress max-suppress-time ]

By default, interface dampening is disabled on Ethernet interfaces.

Setting the statistics polling interval

About this task

To display the interface statistics collected in the last statistics polling interval, use the display interface command. To clear the interface statistics, use the reset counters interface command.

Restrictions and guidelines for setting the statistics polling interval

·     As a best practice, use the default setting when you set the statistics polling interval in system view. A short statistics polling interval might decrease the system performance and result in inaccurate statistics.

Setting the statistics polling interval in Ethernet interface view

1.     Enter system view.

system-view

2.     Enter Ethernet interface view.

interface interface-type interface-number

3.     Set the statistics polling interval for the Ethernet interface.

flow-interval interval

By default, the statistics polling interval is 300 seconds.

Restoring the default settings for an interface

Restrictions and guidelines

	CAUTION: This feature might interrupt ongoing network services. Make sure you are fully aware of the impacts of this feature when you use it in a live network.

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This feature might fail to restore the default settings for some commands because of command dependencies or system restrictions. You can use the display this command in interface view to check for these commands and perform their undo forms or follow the command reference to restore their default settings. If your restoration attempt still fails, follow the error message to resolve the problem.

Procedure

1.     Enter system view.

system-view

2.     Enter Ethernet interface view.

interface interface-type interface-number

3.     Restore the default settings for the interface.

default

Display and maintenance commands

Execute display commands in any view and reset commands in user view.

 

Task	Command
Display interface traffic statistics.	display counters { inbound | outbound } interface [ interface-type [ interface-number ] ]
Display traffic rate statistics of interfaces in up state over the last statistics polling interval.	display counters rate { inbound | outbound } interface [ interface-type [ interface-number ] ]
Display the Ethernet module statistics.	display ethernet statistics slot slot-number
Display the operational and status information of the specified interfaces.	display interface [ interface-type [ interface-number ] ] [ brief [ description | down ] ]
Display information about dropped packets on the specified interfaces.	display packet-drop { interface [ interface-type [ interface-number ] ] | summary }
Clear interface statistics.	reset counters interface [ interface-type [ interface-number ] ]
Clear the Ethernet module statistics.	reset ethernet statistics [ slot slot-number ]
Clear the statistics of dropped packets on the specified interfaces.	reset packet-drop interface [ interface-type [ interface-number ] ]

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