· Layer 3 Ethernet interfaces—Physical Ethernet interfaces operating at the network layer (Layer 3) to route packets. You can assign an IP address to a Layer 3 Ethernet interface.

· Layer-configurable Ethernet interfaces—Physical Ethernet interfaces that can be configured to operate in bridge mode as Layer 2 Ethernet interfaces or in route mode as Layer 3 Ethernet interfaces.

· Layer 3 Ethernet subinterfaces—Logical interfaces operating at the network layer. You can assign an IP address to a Layer 3 Ethernet subinterface. On a Layer 3 Ethernet interface, you can create multiple Layer 3 subinterfaces.

This chapter describes how to configure management Ethernet interfaces and Ethernet interfaces.

Configuring a management Ethernet interface

About management Ethernet interface

A management Ethernet interface uses an RJ-45/LC connector. You can connect the interface to a PC for software loading and system debugging, or connect it to a remote NMS for remote system management.

Restrictions and guidelines

The management Ethernet interface can be a copper port or fiber port.

· By default, the duplex mode is auto for a copper port and full for a fiber port. The duplex command cannot modify the duplex mode to any value other than the default for the copper port or fiber port.

· By default, the speed is auto for a copper port and 1000 Mbps for a fiber port. The speed command cannot modify the speed to any value other than the default for the copper port or fiber port.

In standalone mode, when the switch has multiple management Ethernet interfaces, only the management Ethernet interface on the active MPU processes management traffic.

In IRF mode, when an IRF system has multiple management Ethernet interfaces, only the management Ethernet interface on the global active MPU processes management traffic.

Configuration procedure

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter management Ethernet interface view.	interface M-GigabitEthernet interface-number	N/A
3. (Optional.) Set the interface description.	description text	The default setting is M-GigabitEthernet0/0/0 Interface.
4. (Optional.) Shut down the interface.	shutdown	By default, the management Ethernet interface is up.

Ethernet interface naming conventions

When the switches operate in standalone mode, the Ethernet interfaces are named in the format of interface-type A/B/C, where the following definitions apply:

· A—Represents the slot number of a card.

· B—Represents the number of a subcard on a card. If the card has no subcards, this value is 0.

· C—Represents the number of an interface.

When the switches operate in IRF mode, the Ethernet interfaces are named in the format of interface-type A/B/C/D, where the following definitions apply:

· A—Represents the member ID of an IRF member switch. This value is 1 or 2.

· B—Represents the slot number of the card.

· C—Represents the number of a subcard on a card. If the card has no subcards, this value is 0.

· D—Represents the number of an interface.

Configuring common Ethernet interface settings

This section describes the settings common to Layer 2 Ethernet interfaces, Layer 3 Ethernet interfaces, and Layer 3 Ethernet subinterfaces. For more information about the settings specific to Layer 2 Ethernet interfaces or subinterfaces, see "Configuring a Layer 2 Ethernet interface." For more information about the settings specific to Layer 3 Ethernet interfaces or subinterfaces, see "Configuring a Layer 3 Ethernet interface or subinterface."

A combo interface is a logical interface that physically comprises one fiber combo port and one copper combo port. The two ports share one forwarding channel and one interface view. As a result, they cannot work simultaneously. When you activate one port, the other port is automatically disabled. In the interface view, you can activate the fiber or copper combo port, and configure other port attributes such as the interface rate and duplex mode.

Configuration prerequisites

Before you configure combo interfaces, complete the following tasks:

· Determine the combo interfaces on your device. Identify the two physical interfaces that belong to each combo interface according to the marks on the device panel.

· Use the display interface command to determine which port (fiber or copper) of each combo interface is active:

¡ If the copper port is active, the output includes "Media type is twisted pair."

¡ If the fiber port is active, the output does not include this information.

Changing the active port of a combo interface

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Activate the copper combo port or fiber combo port.	combo enable { copper \| fiber }	By default, the fiber combo port is active.

Splitting a 40-GE interface and combining 10-GE breakout interfaces

Restrictions and guidelines

This feature is not supported on non-default MDCs.

On an LSUM2QGS24RSG0 interface module, this feature is supported on interfaces 1 through 16.

On an LSUM1CGS8QSSH0 interface module, this feature is not supported on 40-GE interfaces.

On an LSUM1CQGS32SF0 interface module, this feature is not supported on 40-GE interfaces.

Splitting a 40-GE interface into four 10-GE breakout interfaces

IMPORTANT:

For this configuration to survive a reboot, save the configuration before rebooting the switch.

You can use a 40-GE interface as a single interface. To improve port density, reduce costs, and improve network flexibility, you can also split a 40-GE interface into four 10-GE breakout interfaces. The 10-GE breakout interfaces support the same configuration and attributes as common 10-GE interfaces, except that they are numbered differently.

For example, you can split 40-GE interface FortyGigE 1/0/1 into four 10-GE breakout interfaces Ten-GigabitEthernet 1/0/1:1 through Ten-GigabitEthernet 1/0/1:4.

A 40-GE interface split into four 10-GE breakout interfaces must use a dedicated 1-to-4 cable. For more information about the cable, see the installation guide.

After you configure this feature on a 40-GE interface on an interface card, reboot the interface card to make the configuration take effect. Do not assign the changed interfaces to any non-default MDC before rebooting the interface card.

To split a 40-GE interface into four 10-GE breakout interfaces:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter 40-GE interface view.	interface interface-type interface-number	N/A
3. Split the 40-GE interface into four 10-GE breakout interfaces.	using tengige	By default, a 40-GE interface is not split and operates as a single interface.

Combining four 10-GE breakout interfaces into a 40-GE interface

IMPORTANT:

For this configuration to survive a reboot, save the configuration before rebooting the switch.

If you need higher bandwidth on a single interface, you can combine the four 10-GE breakout interfaces into a 40-GE interface.

After you combine the four 10-GE breakout interfaces, replace the dedicated 1-to-4 cable with a dedicated 1-to-1 cable or a 40-GE transceiver module. For more information about the cable or transceiver module, see the installation guide.

After you configure this feature on a 10-GE breakout interface on an interface card, reboot the interface card to make the configuration take effect. Do not assign the changed interfaces to any non-default MDC before rebooting the interface card.

To combine four 10-GE breakout interfaces into a 40-GE interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter the view of any 10-GE breakout interface.	interface interface-type interface-number	N/A
3. Combine the four 10-GE breakout interfaces into a 40-GE interface.	using fortygige	By default, a 40-GE interface is not split and operates as a single interface.

Splitting a 100-GE interface and combining 10-GE breakout interfaces

About 100-GE interface splitting and 10-GE breakout interface combining

You can use a 100-GE interface as a single interface. To improve port density, reduce costs, and improve network flexibility, you can also split a 100-GE interface into multiple 10-GE breakout interfaces. The 10-GE breakout interfaces support the same configuration and attributes as common 10-GE interfaces, except that they are numbered differently. For example, you can split 100-GE interface HundredGigE 1/0/1 installed with a split-capable 40-GE transceiver module or copper cable into four 10-GE breakout interfaces Ten-GigabitEthernet 1/0/1:1 through Ten-GigabitEthernet 1/0/1:4.

If you need higher bandwidth on a single interface, you can combine the four 10-GE breakout interfaces into a 100-GE interface. You can execute the combining command on any of the four 10-GE breakout interfaces.

Restrictions and guidelines for 100-GE interface splitting and 10-GE breakout interface combining

· This feature is supported only on the following interfaces:

¡ All 100-GE interfaces on the LSUM1CGS20XSH0 interface modules.

¡ 100-GE interfaces numbered 5 through 12 on the LSUM1CGS8QSSH0 interface modules.

¡ The first seven 100-GE interfaces on the LSUM1CGS8SH0 interface modules.

· This feature is supported only on the default MDC.

· A 100-GE interface split into multiple 10-GE breakout interfaces must use a dedicated cable. After you combine the multiple 10-GE breakout interfaces, replace the dedicated cable with a dedicated 1-to-1 cable or a 100-GE transceiver module. For more information about the cable or transceiver module, see the installation guides.

· For the interface type changes to take effect, you must reboot the interface module where the interface resides.

Splitting a 100-GE interface into multiple 10-GE breakout interfaces

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter 100-GE interface view.	interface hundredgige interface-number	N/A
3. Split the 100-GE interface into multiple 10-GE breakout interfaces.	using tengige	By default, a 100-GE interface is not split and operates as a single interface.

Combining multiple 10-GE breakout interfaces into a 100-GE interface

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter the view of any 10-GE breakout interface.	interface ten-gigabitethernet interface-number	N/A
3. Combine the multiple 10-GE breakout interfaces into a 100-GE interface.	using hundredgige	By default, a 100-GE interface is not split and operates as a single interface.

Splitting a 100-GE interface and combining 25-GE breakout interfaces

About 100-GE interface splitting and 25-GE breakout interface combining

You can use a 100-GE interface as a single interface. To improve port density, reduce costs, and improve network flexibility, you can also split a 100-GE interface into four 25-GE breakout interfaces. The 25-GE breakout interfaces support the same configuration and attributes as common 25-GE interfaces, except that they are numbered differently.

For example, you can split 100-GE interface HundredGigE 1/0/1 into four 25-GE breakout interfaces Twenty-FiveGigE 1/0/1:1 through Twenty-FiveGigE 1/0/1:4.

If you need higher bandwidth on a single interface, you can combine the four 25-GE breakout interfaces into a 100-GE interface.

Restrictions and guidelines for 100-GE interface splitting and 25-GE breakout interface combining

· This feature is supported only on the following interfaces:

¡ All 100-GE interfaces on the LSUM1CGS20XSH0 interface modules.

¡ 100-GE interfaces numbered 5 through 12 on the LSUM1CGS8QSSH0 interface modules.

¡ The first seven 100-GE interfaces on the LSUM1CGS8SH0 interface modules.

· This feature is supported only on the default MDC.

· A 100-GE interface split into four 25-GE breakout interfaces must use a dedicated 1-to-4 cable. After you combine the four 25-GE breakout interfaces, replace the dedicated 1-to-4 cable with a dedicated 1-to-1 cable or a 100-GE transceiver module. For more information about the cable or transceiver module, see the installation guides.

· For the interface type changes to take effect, you must reboot the interface module where the interface resides.

Splitting a 100-GE interface into four 25-GE breakout interfaces

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter 100-GE interface view.	interface hundredgige interface-number	N/A
3. Split the 100-GE interface into four 25-GE breakout interfaces.	using twenty-fivegige	By default, a 100-GE interface is not split and operates as a single interface.

Combining four 25-GE breakout interfaces into a 100-GE interface

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter the view of any 25-GE breakout interface.	interface twenty-fivegige interface-number	N/A
3. Combine the four 25-GE breakout interfaces into a 100-GE interface.	using hundredgige	By default, a 100-GE interface is not split and operates as a single interface.

Changing the interface type of 100-GE interfaces in batches

IMPORTANT:

· This feature is not supported on non-default MDCs.

· The interfaces to be changed in batches must be on the same card.

Restrictions and guidelines

This feature is supported only on the LSUM1CGS8QSSH0LSUM2CQGS12SG0 and LSUM1CQGS32SF0 interface modules.

On the LSUM1CGS8QSSH0 interface modules, only 40-GE interfaces numbered 1 through 4 and 13 through 16 can be changed to 100-GE interfaces when they operate in Layer 2 mode and are not configured as IRF physical interfaces. After you change the interface type, only odd-numbered interfaces (interfaces numbered 1, 3, 13, and 15) are available, and these interfaces do not support 40-GE transceiver modules. For more information about IRF physical interfaces, see IRF configuration in Virtual Technologies Configuration Guide.

On the LSUM2CQGS12SG0 interface modules, after you change each group of 40-GE interfaces to 100-GE interfaces, only interfaces 1, 4, 7, and 10 are available. On the LSUM1CQGS32SF0 interface modules, after you change each group of 40-GE interfaces to 100-GE interfaces, only interfaces of odd number are available.

Reboot the interface module after you configure this feature. Do not assign the changed interfaces to any non-default MDC before rebooting the interface module.

For this configuration to survive a reboot, save the running configuration before rebooting the device.

Changing 100-GE interfaces to 40-GE interfaces in batches

To improve network flexibility, you can change 100-GE interfaces to 40-GE interfaces in batches. For this configuration to succeed, you must specify the available interface numbers. For this configuration to succeed on the LSUM1CQGS32SF0 interface modules, make sure all interfaces in one group are specified in this configuration. Two continuous interfaces of odd number starting from 1 are organized into one group.

To change 100-GE interfaces to 40-GE interfaces in batches:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Change 100-GE interfaces to 40-GE interfaces.	using fortygige-from-hundredgige interface { interface-type interface-number [ to interface-type interface-number ] } &<1-24>	N/A

Changing 40-GE interfaces to 100-GE interfaces in batches

To improve network flexibility, you can change 40-GE interfaces to 100-GE interfaces in batches. For this configuration to succeed, make sure all interfaces in one group are specified in this configuration.

On the LSUM2CQGS12SG0 interface modules, three continuous interfaces starting from 1 are organized into one group and are changed to one 100-GE interface. On the LSUM1CQGS32SF0 interface modules, four continuous interfaces starting from 1 are organized into one group and are changed to two 100-GE interfaces.

On the LSUM1CGS8QSSH0 interface modules, FortyGigE 1/0/1 through FortyGigE 1/0/4 are in one group, and FortyGigE 1/0/13 through FortyGigE 1/0/16 are in one group. Each group of interfaces can be changed to two 100-GE interfaces.

To change 40-GE interfaces to 100-GE interfaces in batches:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Change 40-GE interfaces to 100-GE interfaces.	using hundredgige-from-fortygige interface { interface-type interface-number [ to interface-type interface-number ] } &<1-24>	N/A

Configuring basic settings of an Ethernet interface or subinterface

About basic settings of an Ethernet interface

You can configure an Ethernet interface to operate in one of the following duplex modes:

· Full-duplex mode—The interface can send and receive packets simultaneously.

· Half-duplex mode—The interface can only send or receive packets at a given time.

· Autonegotiation 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.

Restrictions and guidelines

The internal interfaces of OAP modules do not support the duplex mode and speed configuration. For more information, see OAA Configuration Guide.

You cannot configure both 10 Mbps and half duplex mode for interfaces with copper port transceiver modules installed on the following interface modules:

· FD interface modules

· SE interface modules

When a 25-GE interface on an LSUM1YGS48XSH0 interface module has a 10-Gbps or 1-Gbps transceiver module installed, set the speed of the interface to the speed of the transceiver module. When you set the speed for an interface, the speed will also be set for interfaces in the same group. Four continuous interfaces starting from 1 are organized into one group.

Set the duplex mode to full and speed to 1000 Mbps for the specified 10GE interfaces with 1-Gbps transceiver modules installed on the following interface modules:

· FD interface modules: interfaces 29 through 36 on LSUM1GP40TS8FD0, interfaces 17 through 24 on LSUM1TGS24FD0, and interfaces 9 through 16 on LSUM1TGS16FD0

· LSUM1TGS48RSH0 interface modules: all 10-GE interfaces.

· LSUM1TGS48SH0 interface modules: all 10-GE interfaces.

Set the duplex mode to full and speed to 1000 Mbps for both the local interface and the peer inter when a 25-GE interface has a 1-Gbps transceiver module installed on the following interface modules:

· LSUM1YGS24CSSH0 interface modules.

· LSUM1YGS48XSH0 interface modules.

The last eight 10-GE interfaces on the LSUM1TGT24FD0 interface module support only the speed higher than 100 Mbps. The system prompts this interface speed restriction when you configure an unsupported speed.

Configuration procedure

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Set the description for the Ethernet interface.	description text	The default setting is interface-name Interface.
4. Set the duplex mode for the Ethernet interface.	duplex { auto \| full \| half }	Fiber ports do not support the half keyword. By default, the duplex mode is auto for Ethernet interfaces. For interfaces at two ends of a physical link to operate correctly, configure the same duplex mode for them. Interfaces that operate in 1000 Mbps or a higher speed do not support the half keyword and cannot autonegotiate the half duplex mode with the peer.
5. Set the speed for the Ethernet interface.	speed { 10 \| 100 \| 1000 \| 2500 \| 5000 \| 10000 \| 25000 \| 40000 \| 100000 \| auto }	By default, an Ethernet interface autonegotiates the speed with its peer. Support for the keywords of this command varies by interface type. For more information, execute the speed ? command in interface view. For interfaces at two ends of a physical link to operate correctly, configure the same speed for them. The speed of a 10-Gbps or faster fiber port cannot be configured or autonegotiated as 100 Mbps or lower.
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. Restore the default settings for the Ethernet interface.	default	N/A
8. Bring up the Ethernet interface.	undo shutdown	B y default, an Ethernet interface is up. The shutdown, port up-mode, and loopback commands are mutually exclusive.

Configuring an Ethernet subinterface

When you configure an Ethernet subinterface, follow these restrictions and guidelines:

· To transmit packets between a local Ethernet subinterface and a remote Ethernet subinterface, configure them with the same subinterface number and VLAN ID.

· Do not use the VLAN whose ID is an Ethernet subinterface number.

To configure an Ethernet subinterface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Create an Ethernet subinterface.	interface interface-type interface-number.subnumber	N/A
3. Set the description for the Ethernet subinterface.	description text	The default setting is interface-name Interface.
4. Restore the default settings for the Ethernet subinterface.	default	N/A
5. Set the expected bandwidth for the Ethernet subinterface.	bandwidth bandwidth-value	By default, the expected bandwidth (in kbps) is the interface baud rate divided by 1000.
6. Bring up the Ethernet subinterface.	undo shutdown	By default, an Ethernet subinterface is up. Do not use the shutdown command on an interface configured with the loopback command.

Configuring the link mode of an Ethernet interface

CAUTION:

After you change the link mode of an Ethernet interface, all commands (except the shutdown commands) on the Ethernet interface are restored to their defaults in the new link mode.

The Ethernet interfaces can operate either as Layer 2 or Layer 3 Ethernet interfaces. You can set the link mode to bridge or route.

In an IRF 3.1 system, Ethernet interfaces on PEXs cannot be configured as Layer 3 Ethernet interfaces.

The following interfaces do not support the link mode configuration:

· IRF physical interfaces (see Virtual Technologies Configuration Guide).

· Reflector ports used in remote source mirroring groups (see Network Management and Monitoring Configuration Guide).

· EVB-enabled interfaces (see EVB Configuration Guide).

To configure the link mode of an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Configure the link mode of the Ethernet interface.	port link-mode { bridge \| route }	By default, an Ethernet interfaces operates in bridge mode.

Configuring jumbo frame support

An Ethernet interface might receive frames larger than the standard Ethernet frame size during high-throughput data exchanges, such as file transfers. These frames are called jumbo frames.

The Ethernet interface processes jumbo frames in the following ways:

· When you configure the Ethernet interface to deny jumbo frames by using the undo jumboframe enable command, the Ethernet interface discards jumbo frames.

· When you configure the Ethernet interface 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.

To configure jumbo frame support in interface view:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Configure jumbo frame support.	jumboframe enable [ size ]	By default, an Ethernet interface allows jumbo frames within 9126 bytes to pass through. If you set the size argument multiple times, the most recent configuration takes effect.

Configuring physical state change suppression on an Ethernet interface

The physical link state of an Ethernet interface is either up or down. Each time the physical link of an interface comes up or goes down, the interface immediately reports the change to the CPU. The CPU then performs the following operations:

· Notifies the upper-layer protocol modules (such as routing and forwarding modules) of the change for guiding packet forwarding.

· Automatically generates traps and logs to inform users to take the correct actions.

To prevent frequent physical link flapping from affecting system performance, configure physical state change suppression. You can configure this feature to suppress only link-down events, only link-up events, or both. If an event of the specified type still exists when the suppression interval expires, the system reports the event to the CPU.

Configuration restrictions and guidelines

Do not enable this feature on an interface with RRPP, spanning tree protocols, or Smart Link enabled.

This command, the dampening command, and the port link-flap protect enable command are mutually exclusive on an interface.

You can configure different suppression intervals for link-up and link-down events.

If you execute the link-delay command multiple times on an interface, the following rules apply:

· You can configure the suppression intervals for link-up and link-down events separately.

· If you configure the suppression interval multiple times for link-up or link-down events, the most recent configuration takes effect.

Configuration procedure

To configure physical state change suppression on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Configure physical state change suppression.	link-delay { down \| up } [ msec ] delay-time	By default, an Ethernet interface immediately reports the physical state change to the CPU.

Configuring dampening on an Ethernet interface

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

Configuration restrictions and guidelines

When you configure dampening on an Ethernet interface, follow these restrictions and guidelines:

· The dampening, link-delay, and port link-flap protect enable commands are mutually exclusive on an interface.

· 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.

· Do not enable the dampening feature on an interface with RRPP, MSTP, or Smart Link enabled.

Configuration procedure

To configure dampening on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable dampening on the interface.	dampening [ half-life reuse suppress max-suppress-time ]	By default, interface dampening is disabled on Ethernet interfaces.

Enabling link flapping protection on an interface

Link flapping on an interface changes network topology and increases the system overhead. For example, in an active/standby link scenario, when interface status on the active link changes between UP and DOWN, traffic switches between active and standby links. To solve this problem, configure this feature on the interface.

With this feature enabled on an interface, when the interface goes down, the system enables link flapping detection. During the link flapping detection interval, if the number of detected flaps reaches or exceeds the link flapping detection threshold, the system shuts down the interface.

Configuration restrictions and guidelines

This feature takes effect only if it is configured in both the system view and interface view.

The dampening, link-delay, and port link-flap protect enable commands are mutually exclusive on an Ethernet interface.

To bring up an interface that has been shut down by link flapping protection, execute the undo shutdown command.

In the display interface command output, the Link-Flap DOWN value of the Current state field indicates that the interface has been shut down by link flapping protection.

Configuration procedure

To enable link flapping protection on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable link flapping protection globally.	link-flap protect enable	By default, link flapping protection is disabled globally.
3. Enter Ethernet interface view.	interface interface-type interface-number	N/A
4. Enable link flapping protection on the Ethernet interface.	port link-flap protect enable [ interval interval \| threshold threshold ] *	By default, link flapping protection is disabled on an Ethernet interface.

Configuring FEC

About FEC

The forward error correction (FEC) feature corrects packet errors to improve transmission quality. It attaches correction information to a packet at the sending end, and corrects error codes generated during transmission at the receiving end based on the correction information. You can set the FEC mode as needed.

Restrictions and guidelines

This feature is supported only on 25-GE interfaces and 100-GE interfaces.

When the speed of a 25-GE interface is set or autonegotiated to 1000 or 10000 Mbps, FEC does not take effect on the interface.

A 100-GE interface connected through a copper cable or installed with a 40-Gbps transceiver module does not support FEC. If FEC has been configured on the interface, use the undo port fec mode command to restore the default.

When the FEC mode is set to auto on an interface, the actual FEC mode of the interface depends on the model of the transceiver module installed. To view the actual FEC mode, see the FEC mode field in the display interface command output.

Make sure you set the same FEC mode for both interfaces of a link.

Procedure

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Set the FEC mode of the Ethernet interface.	port fec mode { auto \| base-r \| none \| rs-fec }	The default is RS-FEC for 25-GE interfaces and auto for 100-GE interfaces. 100-GE interfaces do not support the base-r keyword.

Configuring link compensation

About link compensation

As the signal transmission rate or frequency increases, high frequency components in signals attenuate more severely. For signal transmission performance, common signal compensation technologies such as pre-emphasis and equalization are introduced. Pre-emphasis amplifies high frequency components but increases the probability of crosstalk. Equalization is introduced to filter out high frequency crosstalk on the receiving end.

Link compensation enables the sending and receiving ends to exchange pre-emphasis and equalization parameters through frames. This feature improves the performance of pre-emphasis and equalization.

Restrictions and guidelines

This feature is supported only on 25-GE interfaces connected through copper cables.

You must enable or disable link compensation on both interfaces of a link.

Procedure

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Configure link compensation on the interface.	port training { disable \| enable }	By default, link compensation is enabled.

Enabling loopback testing on an Ethernet interface

Perform this task to determine whether an Ethernet link works correctly.

Loopback testing includes the following types:

· Internal loopback testing—Tests the device where the Ethernet interface resides. The Ethernet interface sends outgoing packets back to the local device. If the device fails to receive the packets, the device fails.

· External loopback testing—Tests the inter-device link. The Ethernet interface sends incoming packets back to the remote device. If the remote device fails to receive the packets, the inter-device link fails.

Configuration restrictions and guidelines

· After you enable this feature on an Ethernet interface, the interface does not forward data traffic.

· The shutdown, port up-mode, and loopback commands are mutually exclusive.

· Enabling loopback testing on an interface will invalidate the voice VLAN, MAC learning limit, MAC address learning, 802.1X, and MAC authentication configurations on the interface. To make these features take effect on the interface, disable loopback testing and configure the features again.

· This feature is used only for debugging and troubleshooting.

Configuration procedure

To enable loopback testing on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable loopback testing.	loopback { external \| internal }	By default, loopback testing is disabled on an Ethernet interface. The external keyword is not supported in the current software version.

Configuring generic flow control on an Ethernet interface

IMPORTANT:

· This feature is not supported on interfaces that operate in half duplex mode.

· Enabling or disabling this feature on an interface will cause the interface to go down and then come up.

To avoid dropping packets on a link, you can enable generic flow control at both ends of the link. When traffic congestion occurs at the receiving end, the receiving end sends a flow control (Pause) frame to ask the sending end to suspend sending packets. Generic flow control includes the following types:

· TxRx-mode generic flow control—Enabled by using the flow-control command. With TxRx-mode generic flow control enabled, an interface can both send and receive flow control frames:

¡ When congestion occurs, the interface sends a flow control frame to its peer.

¡ When the interface receives a flow control frame from its peer, it suspends sending packets to its peer.

· Rx-mode generic flow control—Enabled by using the flow-control receive enable command. With Rx-mode generic flow control enabled, an interface can receive flow control frames, but it cannot send flow control frames:

¡ When congestion occurs, the interface cannot send flow control frames to its peer.

¡ When the interface receives a flow control frame from its peer, it suspends sending packets to its peer.

To handle unidirectional traffic congestion on a link, configure the flow-control receive enable command at one end and the flow-control command at the other end. To enable both ends of a link to handle traffic congestion, configure the flow-control command at both ends.

Configuration restrictions and guidelines

This feature is not supported on 10-GE interfaces operating at 1000 Mbps on the following interface modules:

· FD interface modules: LSUM1GP40TS8FD0, LSUM1TGS24FD0, and LSUM1TGS16FD0

This feature is not supported on 10-GE interfaces operating at 1000 Mbps on the LSUM1TGS48RSH0 and LSUM1TGS48SH0 interface modules.

Configuration procedure

To enable generic flow control on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable generic flow control.	· Enable TxRx-mode generic flow control: flow-control · Enable Rx-mode generic flow control: flow-control receive enable	By default, generic flow control is disabled on an Ethernet interface.

Configuring PFC on an Ethernet interface

When congestion occurs in the network, the local device notifies the peer to stop sending packets carrying the specified 802.1p priority if all of the following conditions exist:

· Both the local end and the remote end have PFC enabled.

· Both the local end and the remote end have the priority-flow-control no-drop dot1p command configured.

· The specified 802.1p priority is in the 802.1p priority list specified by the dot1p-list argument.

· The local end receives a packet carrying the specified 802.1p priority.

The state of the PFC feature is determined by the PFC configuration on the local end and on the peer end. In Table 1:

· The first row lists the PFC configuration on the local interface.

· The first column lists the PFC configuration on the peer.

· The Enabled and Disabled fields in other cells are possible negotiation results.

Make sure all interfaces that a data flow passes through have the same PFC configuration.

Table 1 PFC configurations and negotiation results

Local (right) Peer (below)	enable	auto	Default
enable	Enabled	Enabled.	Disabled
auto	Enabled	· Enabled if negotiation succeeds. · Disabled if negotiation fails.	Disabled
Default	Disabled	Disabled.	Disabled

Configuration restrictions and guidelines

You can configure PFC in both system view and Ethernet interface view. If you configure PFC in system view and Ethernet interface view multiple times, the most recent configuration takes effect.

PFC is supported only on interfaces on the following interface modules:

· SH interface modules.

Only Ethernet interfaces on the following interface modules can be both configured as IRF physical interfaces and configured with PFC:

· LSUM1TGS24EC0 interface modules.

· LSUM1QGS6EC0 interface modules.

Among 100-GE interfaces, only 100-GE interfaces on SH interface modules support PFC.

This feature is not supported on 10-GE interfaces operating at 1000 Mbps on the following interface modules:

· FD interface modules: LSUM1GP40TS8FD0, LSUM1TGS24FD0, and LSUM1TGS16FD0

This feature is not supported on 10-GE interfaces operating at 1000 Mbps on the LSUM1TGS48RSH0 and LSUM1TGS48SH0 interface modules.

To perform PFC on an IRF port, configure PFC on the IRF port and the IRF physical interfaces that are bound to the IRF port. You must first configure PFC on IRF physical interfaces and then enable PFC globally. For information about IRF, see Virtual Technologies configuration Guide.

For IRF and other protocols to operate correctly, as a best practice, do not enable PFC for 802.1p priorities 0, 6, and 7.

To avoid packet loss, apply the same PFC configuration to all interfaces that the packets pass through.

If you do not enable PFC on an interface, the interface can receive but cannot process PFC pause frames. To make PFC take effect, you must enable PFC on both ends.

For PFC to operate correctly for an 802.1p priority, make sure the 802.1p priority uses the default 802.1p-local priority map. For more information about the default 802.1p-local priority map, see ACL and QoS Configuration Guide. To configure the 802.1p-to-local priority map, use the import command in 802.1p-to-local priority map view. For more information about the import command, see ACL and QoS Command Reference.

The relationship between PFC and generic flow control is shown in Table 2.

Table 2 The relationship between PFC and generic flow control

flow-control	priority-flow-control enable	priority-flow-control no-drop dot1p	Remarks
Unconfigurable	Configured	Configured	After you enable PFC on an interface and for the specified 802.1p priorities, you cannot enable generic flow control on the interface.
Configured	Configurable	Unconfigurable	After you enable generic flow control on an interface, you can enable PFC on the interface but not for the specified 802.1p priorities.

Configuring PFC on inner interfaces

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable PFC on inner interfaces.	priority-flow-control inner-port enable	By default, PFC is disabled on inner interfaces. An inner interface is the inner Ethernet interface through which a card communicates with the device, and is invisible for users.
3. Enable PFC for 802.1p priorities on inner interfaces.	priority-flow-control inner-port no-drop dot1p dot1p-list	By default, PFC is disabled for all 802.1p priorities.

Configuring PFC in system view

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enable PFC on all Ethernet interfaces.	priority-flow-control { auto \| enable [ receive \| send ] }	By default, PFC is disabled on all Ethernet interfaces.
3. Enable PFC for 802.1p priorities on all Ethernet interfaces.	priority-flow-control no-drop dot1p dot1p-list	By default, PFC is disabled for all 802.1p priorities on all Ethernet interfaces.

Configuring PFC on an Ethernet interface

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable PFC on the Ethernet interface.	priority-flow-control { auto \| enable [ receive \| send ] }	By default, PFC is disabled on an Ethernet interface.
4. Enable PFC for 802.1p priorities.	priority-flow-control no-drop dot1p dot1p-list	By default, PFC is disabled for all 802.1p priorities.
5. (Optional.) Set the pause time in PFC pause frames.	priority-flow-control pause-time time-vale	By default, the pause time in PFC pause frames is 65535.

Enabling EEE on an Ethernet interface

With Energy Efficient Ethernet (EEE) enabled, a link-up interface enters low power state if it has not received any packet for a period of time. The time period depends on the chip specifications and is not configurable. When a packet arrives later, the device automatically restores power supply to the interface and the interface restores to the normal state.

Configuration restrictions and guidelines

This feature is supported only on copper ports on the following interface modules:

· LSUM1GT48FD0.

· LSUM1TGT24FD0.

· LSUM2GT24PTSSE0

· LSUM2GT24TSSE0.

· LSUM2GT48SE0.

For this feature to take effect on an interface, configure the interface to automatically negotiate a speed or duplex mode with the remote end.

Configuration procedure

To enable EEE on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable EEE on the Ethernet interface.	eee enable	By default, EEE is disabled on an Ethernet interface.

Setting the statistics polling interval

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Set the statistics polling interval for the Ethernet interface.	flow-interval interval	By default, the statistics polling interval is 300 seconds.

To display the interface statistics collected in the most recent statistics polling interval, use the display interface command.

Forcibly bringing up a fiber port

As shown in Figure 2, a fiber port uses separate fibers for transmitting and receiving packets. The physical state of the fiber port is up only when both transmit and receive fibers are physically connected. If one of the fibers is disconnected, the fiber port does not work.

To enable a fiber port to forward traffic over a single link, you can use the port up-mode command. This command forcibly brings up a fiber port, even when no fiber links or transceiver modules are present for the fiber port. When one fiber link is present and up, the fiber port can forward packets over the link unidirectionally.

Figure 2 Forcibly bring up a fiber port

Configuration restrictions and guidelines

When you forcibly bring up a fiber port, follow these restrictions and guidelines:

· This feature is not supported on the following interfaces:

¡ All interfaces on EC interface modules:

- LSUM1TGS24EC0.

- LSUM1QGS6EC0.

¡ Interfaces numbered 45 through 48 on LSUM2GP44TSSE0 and LSUM2GT24PTSSE0 interface modules.

¡ Interfaces numbered 25 through 28 on LSUM2GP24TSSE0 and LSUM2GT24TSSE0 interface modules.

· For fiber ports connected to the same physical link to operate correctly, you must configure this feature for both of them.

· The port up-mode, shutdown, and loopback commands are mutually exclusive.

· A fiber Ethernet port does not support this feature if the port is shut down by a protocol or by using the shutdown command.

· A fiber Ethernet port does not support this feature if the port joins an aggregate group.

· Either of the following operations on an interface forcibly brought up will cause the interface to go down before staying physically up:

¡ Configure the speed, duplex, or port fec mode command on the interface.

¡ Remove and install fibers or transceiver modules.

· A GE fiber port forcibly brought up cannot correctly forward traffic if it is installed with a fiber-to-copper converter, 100/1000-Mbps transceiver module, or 100-Mbps transceiver module. To solve the problem, use the undo port up-mode command on the fiber port.

Configuration procedure

To forcibly bring up a fiber port:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	Copper ports do not support this feature.
3. Forcibly bring up the fiber port.	port up-mode	By default, a fiber port is not forcibly brought up, and the physical state of a fiber port depends on the physical state of the fibers.

Configuring a Layer 2 Ethernet interface

Configuring storm suppression

The storm suppression feature ensures that the size of a particular type of traffic (broadcast, multicast, or unknown unicast traffic) does not exceed the threshold on an interface. When the broadcast, multicast, or unknown unicast traffic on the interface exceeds this threshold, the system discards packets until the traffic drops below this threshold.

Both storm suppression and storm control can suppress storms on an interface. Storm suppression uses the chip to suppress traffic. Storm suppression has less impact on the device performance than storm control, which uses software to suppress traffic.

Configuration restrictions and guidelines

When you configure storm suppression, follow these restrictions and guidelines:

· For the traffic suppression result to be determined, do not configure storm control together with storm suppression for the same type of traffic. For more information about storm control, see "Configuring storm control on an Ethernet interface."

· The configured suppression threshold value in pps or kbps might be converted into a multiple of a step supported by the chip. As a result, the effective suppression threshold might be different from the configured one. For information about the suppression threshold that takes effect, see the prompt on the device.

· If you configure the suppression threshold in pps for an interface to be greater than 1.4881× actual interface speed, the configuration fails. The speed command and the transceiver module installed affect the actual interface speed of an interface. For example, if a 10-GE fiber port has a 1-Gbps transceiver module installed and has the speed set to 1000 Mbps, the maximum suppression threshold in pps supported by the interface is 1488100.

Configuration procedure

To set storm suppression thresholds on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable broadcast suppression and set the broadcast suppression threshold.	broadcast-suppression { ratio \| pps max-pps \| kbps max-kbps }	By default, broadcast suppression is disabled.
4. Enable multicast suppression and set the multicast suppression threshold.	multicast-suppression { ratio \| pps max-pps \| kbps max-kbps }	By default, multicast suppression is disabled.
5. Enable unknown unicast suppression and set the unknown unicast suppression threshold.	unicast-suppression { ratio \| pps max-pps \| kbps max-kbps }	By default, unknown unicast suppression is disabled.

Configuring storm control on an Ethernet interface

About storm control

Storm control compares broadcast, multicast, and unknown unicast traffic regularly with their respective traffic thresholds on an Ethernet interface. For each type of traffic, storm control provides a lower threshold and an upper threshold.

Depending on your configuration, when a particular type of traffic exceeds its upper threshold, the interface performs either of the following operations:

· Blocks this type of traffic and forwards other types of traffic—Even though the interface does not forward the blocked traffic, it still counts the traffic. When the blocked traffic drops below the lower threshold, the interface begins to forward the traffic.

· Goes down automatically—The interface goes down automatically and stops forwarding any traffic. When the blocked traffic drops below the lower threshold, the interface does not automatically come up. To bring up the interface, use the undo shutdown command or disable the storm control feature.

You can configure an Ethernet interface to output threshold event traps and log messages when monitored traffic meets one of the following conditions:

· Exceeds the upper threshold.

· Drops below the lower threshold.

Storm control uses a complete polling cycle to collect traffic data, and analyzes the data in the next cycle. An interface takes one to two polling intervals to take a storm control action.

Configuration restrictions and guidelines

For the traffic suppression result to be determined, do not configure storm control together with storm suppression for the same type of traffic. For more information about storm suppression, see "Configuring storm suppression."

Configuration procedure

To configure storm control on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. (Optional.) Set the statistics polling interval of the storm control module.	storm-constrain interval interval	The default setting is 10 seconds. For network stability, use the default or set a longer statistics polling interval.
3. Enter Ethernet interface view.	interface interface-type interface-number	N/A
4. (Optional.) Enable storm control, and set the lower and upper thresholds for broadcast, multicast, or unknown unicast traffic.	storm-constrain { broadcast \| multicast \| unicast } { pps \| kbps \| ratio } upperlimit lowerlimit	By default, storm control is disabled.
5. Set the control action to take when monitored traffic exceeds the upper threshold.	storm-constrain control { block \| shutdown }	By default, storm control is disabled.
6. (Optional.) Enable the Ethernet interface to output log messages when it detects storm control threshold events.	storm-constrain enable log	By default, the Ethernet interface outputs log messages when monitored traffic exceeds the upper threshold or drops below the lower threshold after exceeding the upper threshold.
7. (Optional.) Enable the Ethernet interface to send storm control threshold event traps.	storm-constrain enable trap	By default, the Ethernet interface sends traps when monitored traffic exceeds the upper threshold or drops below the lower threshold from the upper threshold after exceeding the upper threshold.

Setting speed options for autonegotiation on an Ethernet interface

About speed options for autonegotiation

By default, speed autonegotiation enables an Ethernet interface to negotiate with its peer for the highest speed that both ends support. You can narrow down the speed option list for negotiation.

Figure 3 Speed autonegotiation application scenario

As shown in Figure 3:

· All interfaces on the device are operating in speed autonegotiation mode, with the highest speed of 1000 Mbps.

· Port D provides access to the Internet for the servers.

If the transmission rate of each server in the server cluster is 1000 Mbps, their total transmission rate exceeds the capability of Port D.

To avoid congestion on Port D, configure 100 Mbps as the only option available for speed negotiation on interfaces Port A, Port B, and Port C. As a result, the transmission rate on each interface connected to a server is limited to 100 Mbps.

Configuration restrictions and guidelines

This feature is supported only on GE copper interfaces.

The speed and speed auto commands supersede each other, and whichever is configured last takes effect.

Configuration procedure

To set speed options for autonegotiation on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Set speed options for autonegotiation.	speed auto { 10 \| 100 \| 1000 } *	No option is set for speed autonegotiation.

Setting the MDIX mode of an Ethernet interface

A physical Ethernet interface has eight pins, each of which plays a dedicated role. For example, pins 1 and 2 transmit signals, and pins 3 and 6 receive signals. You can use both crossover and straight-through Ethernet cables to connect copper Ethernet interfaces. To accommodate these types of cables, a copper Ethernet interface can operate in one of the following Medium Dependent Interface-Crossover (MDIX) modes:

· MDIX mode—Pins 1 and 2 are receive pins and pins 3 and 6 are transmit pins.

· MDI mode—Pins 1 and 2 are transmit pins and pins 3 and 6 are receive pins.

· AutoMDIX mode—The interface negotiates pin roles with its peer.

NOTE:

This feature does not take effect on pins 4, 5, 7, and 8 of physical Ethernet interfaces. Pins 4, 5, 7, and 8 of interfaces operating at 1000 Mbps or higher rates receive and transmit signals.

To enable a copper Ethernet interface to communicate with its peer, set the MDIX mode of the interface by following these guidelines:

· Typically, set the MDIX mode of the interface to AutoMDIX. Set the MDIX mode of the interface to MDI or MDIX only when the device cannot determine the cable type.

· When a straight-through cable is used, configure the interface to operate in an MDIX mode different than its peer.

· When a crossover cable is used, perform one of the following tasks:

¡ Configure the interface to operate in the same MDIX mode as its peer.

¡ Configure either end to operate in AutoMDIX mode.

Configuration restrictions and guidelines

Fiber ports do not support the MDIX mode setting.

Configuration procedure

To set the MDIX mode of an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Set the MDIX mode of the Ethernet interface.	mdix-mode { automdix \| mdi \| mdix }	By default, a copper Ethernet interface operates in auto mode to negotiate pin roles with its peer.

Testing the cable connection of an Ethernet interface

IMPORTANT:

· If the link of an Ethernet interface is up, testing its cable connection will cause the link to go down and then come up.

· Fiber ports do not support this feature.

· Ethernet copper ports on the LSUM1TGT24FD0 interface module do not support this feature.

This feature tests the cable connection of an Ethernet interface and displays cable test result within 5 seconds. The test result includes the cable's status and some physical parameters. If any fault is detected, the test result shows the length from the local port to the faulty point.

To test the cable connection of an Ethernet interface:

Step	Command
1. Enter system view.	system-view
2. Enter Ethernet interface view.	interface interface-type interface-number
3. Perform a test for the cable connected to the Ethernet interface.	virtual-cable-test

Enabling bridging on an Ethernet interface

When a packet arrives at an interface, the switch looks up the destination MAC address of the packet in the MAC address table.

· If the outgoing interface of the entry found is the same as the incoming interface, the switch drops the packet. To enable the switch to forward such packets rather than drop them, enable bridging on the Ethernet interface.

· If no entry is found for the destination MAC address, the switch sends an ARP packet out of all interfaces except the incoming interface. To enable the switch to send the ARP packet out of the incoming interface, enable bridging on the Ethernet interface.

To enable bridging on an Ethernet interface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Enable bridging on the Ethernet interface.	port bridge enable	By default, bridging is disabled on an Ethernet interface.

Configuring a Layer 3 Ethernet interface or subinterface

Setting the MTU for an Ethernet interface or subinterface

The maximum transmission unit (MTU) of an Ethernet interface affects the fragmentation and reassembly of IP packets on the interface. Typically, you do not need to modify the MTU of an interface.

To set the MTU for an Ethernet interface or subinterface:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface or subinterface view.	interface interface-type { interface-number \| interface-number.subnumber }	N/A
3. Set the MTU of the Ethernet interface or subinterface.	mtu size	The default setting is 1500 bytes.

Displaying and maintaining an Ethernet interface or subinterface

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 operational and status information of the specified interfaces.	display interface [ interface-type [ interface-number \| interface-number.subnumber ] ] [ brief [ description \| down ] ]
Display the status and packet statistics of interfaces.	display interface link-info [ main ]
Display the operational and status information of interfaces except subinterfaces.	display interface [ interface-type ] [ brief [ description \| down ] ] main
Display information about link flapping protection on interfaces.	display link-flap protection [ interface interface-type [ interface-number ] ]
Display information about dropped packets on the specified interfaces.	display packet-drop { interface [ interface-type [ interface-number ] ] \| summary }
Display the PFC information for an interface.	display priority-flow-control interface [ interface-type [ interface-number ] ]
Display information about storm control on the specified interfaces.	display storm-constrain [ broadcast \| multicast \| unicast ] [ interface interface-type interface-number ]
(In standalone mode.) Display the Ethernet module statistics.	display ethernet statistics slot slot-number
(In IRF mode.) Display the Ethernet module statistics.	display ethernet statistics chassis chassis-number slot slot-number
Clear interface or subinterface statistics.	reset counters interface [ interface-type [ interface-number \| interface-number.subnumber ] ]
Clear the statistics of dropped packets on the specified interfaces.	reset packet-drop interface [ interface-type [ interface-number ] ]
(In standalone mode.) Clear the Ethernet module statistics.	reset ethernet statistics [ slot slot-number ]
(In IRF mode.) Clear the Ethernet module statistics.	reset ethernet statistics [ chassis chassis-number slot slot-number ]

03-Interface Configuration Guide

Configuring Ethernet interfaces

Configuring a management Ethernet interface

About management Ethernet interface

Restrictions and guidelines

Configuration procedure

Configuration prerequisites

Changing the active port of a combo interface

Restrictions and guidelines

Splitting a 40-GE interface into four 10-GE breakout interfaces

Combining four 10-GE breakout interfaces into a 40-GE interface

About 100-GE interface splitting and 10-GE breakout interface combining

Restrictions and guidelines for 100-GE interface splitting and 10-GE breakout interface combining

Splitting a 100-GE interface into multiple 10-GE breakout interfaces

Combining multiple 10-GE breakout interfaces into a 100-GE interface

About 100-GE interface splitting and 25-GE breakout interface combining

Restrictions and guidelines for 100-GE interface splitting and 25-GE breakout interface combining

Splitting a 100-GE interface into four 25-GE breakout interfaces

Combining four 25-GE breakout interfaces into a 100-GE interface

Changing the interface type of 100-GE interfaces in batches

Restrictions and guidelines

Changing 100-GE interfaces to 40-GE interfaces in batches

Changing 40-GE interfaces to 100-GE interfaces in batches

About basic settings of an Ethernet interface

Restrictions and guidelines

Configuration procedure

Configuration restrictions and guidelines

Configuration procedure

Parameters

Configuration restrictions and guidelines

Configuration procedure

Configuration restrictions and guidelines

Configuration procedure

About FEC

Restrictions and guidelines

Procedure

About link compensation

Restrictions and guidelines

Procedure

Configuration restrictions and guidelines

Configuration procedure

Configuration restrictions and guidelines

Configuration procedure

Configuration restrictions and guidelines

Configuring PFC on inner interfaces

Configuring PFC in system view

Configuring PFC on an Ethernet interface

Configuration procedure

Configuration restrictions and guidelines

Configuration procedure

Configuring storm suppression

Configuration restrictions and guidelines

Configuration procedure

Configuring storm control on an Ethernet interface

About storm control

Configuration restrictions and guidelines

Configuration procedure

Setting speed options for autonegotiation on an Ethernet interface

About speed options for autonegotiation

Configuration restrictions and guidelines

Configuration procedure

Configuration restrictions and guidelines

Configuration procedure

Configuring a Layer 3 Ethernet interface or subinterface

Setting the MTU for an Ethernet interface or subinterface

Displaying and maintaining an Ethernet interface or subinterface

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