To check the MAD configuration, run the display mad command. If the verbose parameter is specified, detailed MAD configuration is displayed, including MAD-enabled interfaces and interfaces excluded from shutdown.

When MAD in relay mode is configured, you can run the display mad proxy command on the proxy device to check its MAD configuration.

To check stack information, including stack topology and stack member switches, run the display stack command.

This command can be used only after the stack function is enabled (default status).

To check information about the neighbors of a member switch, run the display stack peers command.

This command can be used only after the stack function is enabled (default status).

You can run the display stack port command to check summary and detailed information about stack ports.

You can run the display stack port auto-cable-info command to check interfaces supporting dedicated stack cables and whether dedicated stack cables have been connected to interfaces.

You can run the display stack port speed command to check the stack port's current working speed and working speed taking effect after a restart. To set the stack port working speed, run the stack port speed command.

You can run the display stack-port load-balance command to check the load balancing modes of stack ports and then locate data transmission failures between stack links.

Usage Scenario

Stack configuration will only be written to the flash memory instead of the configuration file. As a result, Stack configuration cannot be obtained through the configuration file. To view stack configuration, run the display stack configuration command.

Precautions

• This command is valid only when the stack function is enabled and has taken effect. By default, the stack function is enabled.

• This command displays only the stack commands that have been executed. The displayed command configuration is not necessarily the running stack configuration, because most stack configuration commands take effect after a system restart.

To check stack link connections and status, run the display stack channel all command. If you do not specify all or slot slot-id in the command, this command displays the stack link connections and status of the master switch.

If the stack topology changes after the areas for smooth upgrade are divided, members in the active and backup areas may change, resulting in a smooth upgrade failure. To check whether a smooth upgrade can start in these areas, run the display upgrade area command.

If the areas fail the check, re-define the active and backup areas according to the current stack topology.

The active area contains the master switch.

To check the status of member switches in the active and backup areas before or after a smooth upgrade, run the display upgrade state command.

If you specify the slot slot-id parameter in the command, you can check whether the member switch with this slot ID has been upgraded successfully.

If the master switch of a stack restarts or experiences a master/standby switchover after a smooth upgrade, area information will be deleted from the master switch, and the Area field of the master switch will be displayed as unknown.

Each member switch has two stack ports, which are named Stack-Portn/1 and Stack-Portn/2. n specifies the stack ID of a member switch. After you run the interface stack-port command to enter the view of a stack port, you can configure attributes for the stack port.

Usage Scenario

To ensure that only one switch becomes the master switch after a stack splits, thereby enhancing stack stability, run the mad detect mode direct command to configure MAD in direct mode on an interface.

Configuration Impact

Configuring MAD in direct mode on an interface blocks the interface. Disabling MAD in direct mode on an interface restores the forwarding function of the interface. If a loop exists on the network, a broadcast storm occurs.

Precautions

The undo mad detect command is not supported in the port group view. You can only run the undo mad detect mode direct command in the port group view to disable MAD in direct mode.

Usage Scenario

To ensure that only one switch becomes the master switch after a stack splits, thereby enhancing stability of the stack, run the mad detect mode relay command to configure MAD in relay mode on an Eth-trunk.

Precautions

The undo mad detect command is not supported in the port group view. You can only run the undo mad detect mode relay command in the port group view to disable MAD in relay mode.

In most MAD scenarios, configuring a MAD domain ID for a stack is unnecessary. When two stack systems function as a proxy of each other to implement MAD, configure different MAD domain IDs for the stack systems.

Usage Scenario

If MAD detects a stack split, all service ports of the member switch that fails master switch election must be shut down to prevent network flapping caused by MAC or IP address flapping. If some interfaces only transparently transmit packets, they do not affect network operation in a dual-active condition. You can run the mad exclude command to exclude these interfaces from shutdown before a stack split occurs.

For MAD working in relay mode, run the mad relay command to configure the relay function on an Eth-Trunk interface of a proxy device. Member interfaces of the Eth-Trunk interface exchange MAD packets between member switches.

When MAD detects a multi-active event, the member switch elected as the master switch remains in the Detect state. The elected standby switch enters the Recovery state, shuts down all its service ports except those excluded from shutdown, and stops forwarding service packets.

If the switch in the Detect state fails or is removed before the split stack is restored, run the mad restore command on the switch in the Recovery state to restore the interfaces in shutdown state. The switch in the Recovery state then goes to the Detect state. You can then restore the original switch in the Detect state and rectify the faulty stack links. After the faults are rectified, the two switches form a stack again.

Usage Scenario

In service interface connection mode, run the port interface enable command to configure a service interface as a physical member port to implement the stack function.

Configuration Impact

A stack physical member port supports only stack-related functions, and other functions cannot be configured on the interface. All the commands irrelevant to the stack function are masked in the interface view, and only basic configuration commands, such as description, are retained.

After configuring a service port of a switch as a physical stack member port, you are advised to save the configuration if this service port has been referenced by other commands. Otherwise, the commands that reference this service port may be retained after the switch restarts.

On the S5720I-SI, S5735-S, S500, S5735S-S, S5735-S-I, S5735S-H, S5736-S, and S6720S-S the electrical or optical port stack configuration on the front panel is mutually exclusive with the SVF client mode configuration. If electrical or optical ports on the front panel have been configured as stack physical member ports, SVF management VLAN cannot be configured. If an SVF management VLAN has been configured, electrical or optical ports on the front panel cannot be configured as stack physical member ports.

On the S6720-EI, S6735-S, and S6720S-EI, every four of XGE interfaces from the left are added to one group. For example, XGE interfaces numbered 1 to 4 can be added to one group, but XGE interfaces numbered 2 to 5 cannot. That is, the number of the last XGE interface in each group must be the multiple of 4. If you configure any interface in each group as a physical member port, configurations on the other three interfaces in the group will be lost and the three interfaces cannot be used as service ports.

Precautions

• The stack member ports of a logical stack port must be the same type.
• After a UCL group is created on the S2720-EI, S5720I-SI, S5720-LI, S5720S-LI, or S5720-SI, using the ucl-group command, the port interface enable command cannot be used to configure a service interface as a stack member port.
• To restore a physical member port as a service interface, run the shutdown interface command in the stack port view and then run the undo port interface enable command.

• On the S2720-EI, S5720I-SI, S5720-LI, S2730S-S, S5735-L-I, S5735-L1,S300, S5735-L, S5735S-L, S5735S-L1, S5735S-L-M, S5720S-LI, S5735-S, S500, S5735S-S, S5735-S-I, S5735S-H, S5736-S, and S6720S-S, after a service interface is configured as a stack member port, the following priority mapping rules apply to packets on this interface:

  • Packets sent to the CPU are mapped to queue 7.
  • Packets with priority 0 or 1 are mapped to queue 0.
  • Packets with priorities 2 to 7 are mapped to queues 1 to 6, respectively.

• If the switch functions as an AS in an SVF system and its downlink service ports have been configured as member ports of an uplink fabric port, all the downlink ports of the AS cannot be configured as stack member ports.

Usage Scenario

The cleared stack configuration includes: switch slot ID, stack priority, stack reserved VLAN, stack MAC address switching delay, stack port configuration, and stack port rate configuration. For example, when switches are stacked using dedicated stack cables, to ensure that slot IDs are automatically generated for the switches based on the sequence in which dedicated stack cables are connected, run the reset stack configuration command to clear all stack configuration.

Precautions

• Running this command will cause the stack to split and member switches to restart.
• If there is no device in the slot where an interface resides, running this command automatically clears all configurations on the interface. For example, if the slot ID of the current device is 0 and there is interface 1/0/1 in the configuration file, all configurations on interface 1/0/1 are cleared.

Usage Scenario

Before collecting interface traffic statistics in a certain period of time, run the reset stack port statistics command to clear existing traffic statistics. If you do not specify the port number, statistics on all stack ports are cleared. If you specify the port number, only statistics on the specified port are cleared.

Precautions

The cleared statistics cannot be restored. Therefore, exercise caution when you run the reset stack port statistics command.

This command can be used only after the stack function is enabled (default status).

Usage Scenario

After dedicated stack cables are connected to ports, stack configuration is automatically generated but not saved to the flash memory. If these cables are removed or other cables are connected, the stack configuration is automatically deleted. To ensure that the stack configuration still takes effect when these cables are removed or other cables are connected, run the save stack configuration command.

Precautions

• Removing dedicated stack cables from ports after this command is executed will cause these ports unable to automatically become service ports.
• No stack configurations can be manually modified before the stack configuration automatically generated for dedicated cable stacking is saved to the flash memory.

After fixed switches set up a stack and the standby switch starts, the standby switch restores configurations and then implements batch backup from the master switch.

By default, interfaces on the standby switch become Up when batch backup is complete. In this case, Layer 2 and Layer 3 traffic can be normally forwarded but there is a delay in Layer 2 traffic recovery. To enable fast recovery of Layer 2 traffic, run the set l2-traffic fast-recover enable command. Interfaces on the standby switch then immediately go Up when configuration restoration is complete. This way, however, cannot ensure Layer 3 traffic forwarding through the Up interfaces.

To restore a physical member interface to being a service interface, run the shutdown interface command in the stack interface view and then run the undo port interface enable command.

If there is only one available link on a stack interface, running the shutdown interface command will change the stack status or split the stack. After you run the undo shutdown interface command on the stack interface, the stack will be set up again when a link on the stack interface becomes available.

Usage Scenario

A switch can join a stack without being authenticated. In this situation, an attacker can add any switch to a stack to obtain the configuration file of the stack master switch, resulting in information leak. To solve this problem, configure authentication when a switch needs to join a stack. This configuration ensures that this switch joins the stack only when it is authenticated successfully.

A switch will be authenticated only when its stack ID is the same as that specified in the stack authentication command. Otherwise, this switch can join a stack without being authenticated. Therefore, before adding a switch to a stack, you are advised to change the slot ID of the switch to an unused stack ID in the stack and then configure an authentication mode for this stack ID.

Precautions

• This command can be executed only after the stacking function is enabled.
• Only one authentication mode can be configured for a stack ID, and the latest configuration takes effect.
• If a switch to join a stack fails the authentication, this switch will restart repeatedly.

Stack IDs can be allocated by the master switch when a stack is set up, or you can configure them yourself. If stack IDs are allocated by the master switch, you cannot identify which ID a device maps to. To enable a service port indicator to indicate the stack ID of a stack switch, run the stack led enable command.

The configuration of this command becomes invalid when port indicators show stack IDs of member switches for the specified time.

Use Scenario

To transmit traffic from a stack port to a destination over different links, run the stack-port load-balance mode command to configure an appropriate load balancing mode for the physical member ports of the stack port. Outgoing traffic is then properly balanced among the physical links, preventing congestion on these links. If you run this command multiple times to set different load balancing modes, the last configuration takes effect. The load balancing mode configured in the system view takes effect globally, and the load balancing mode configured in a stack port view takes effect only on the specified stack port. You can run the display stack-port command to view the load balancing mode on a stack port.

Precautions

Usage Scenario

On the S5720-P-LI, S5720-X-LI, S5720I-SI, and S5720S-X-LI,, if optical ports are used as stack member ports and are connected using 1 m or 3 m SFP+ passive copper cables, you can use this command to increase their working speed from 10 Gbit/s to 12 Gbit/s, expanding the stack bandwidth. After their working speed is increased to 12 Gbit/s, switches using these ports cannot set up a stack with switches using ports with the working speed 10 Gbit/s.

On the S6720-SI, only the rate of 40GE interfaces on the front panel can be increased to 48 Gbit/s.

If S5720-P-LI, S5720-X-LI, and S5720S-X-LI switches use XGE optical ports to stack with other switches that have GE optical ports, use this command to reduce the working speed of the XGE optical ports from 10 Gbit/s to 2.5 Gbit/s, so that the XGE optical ports can work with the remote GE optical ports.

Precautions

After changing the working speed of stack member ports, you need to restart the switch for the new speed to take effect.

After the stack port error-down function is enabled, you can run the stack port { crc | link-flap } trigger command to adjust the related parameters.

Usage Scenario

In a stack system, if a stack port continuously receives CRC error packets or flaps between Up and Down states, the corresponding stack link cannot forward traffic normally, thereby affecting network services. This command enables the stack port error-down function. This function can shut down a stack port and switch traffic to other stack links if the rate of received CRC error packets or the number of Up/Down transitions on the stack port reaches the specified threshold, reducing the impact on services. Additionally, the system generates stack port error-down alarms to help in fault location.

Follow-up Procedure

Run the stack port { crc | link-flap } trigger command to set stack port error-down parameters.

Precautions

• When one end is a stack port and the other end is a service port, the system does not set the stack port to error-down state or generate an error-down alarm even if this stack port continuously receives CRC error packets.
• The stack port error-down alarm OID is 1.3.6.1.4.1.2011.5.25.183.1.22.59.
• The stack port error-down alarm clearance OID is 1.3.6.1.4.1.2011.5.25.183.1.22.60.

By default, a stack uses VLAN 4093 as the reserved VLAN. A reserved VLAN is used only to exchange stack protocol packets.

To deploy services in VLAN 4093, run the stack reserved-vlan command to change the reserved VLAN of the stack.

If the reserved VLAN is used for other services, the stack cannot be set up. You must specify an unused VLAN as the reserved VLAN for a stack.

Usage Scenario

To set a stack priority for a member switch in a stack, run the stack slot priority command. A larger priority indicates a higher priority, meaning that a switch is more likely to be selected as a master switch.

Usage Scenario

To change the stack ID of a stack member switch, run the stack slot renumber command.

Precautions

• After changing the stack ID of a switch, if you do not restart the switch, the switch continues to use the original stack ID, and all physical resources are identified by the original stack ID.
• After changing the stack ID of a switch, if you restarts the switch, the new stack ID takes effect and all physical resources are identified by the new stack ID. In the configuration file, only the global stack configuration and stack priority of the switch continue to take effect. All other configurations related to the old stack ID (such as interface configuration) become invalid and must be reconfigured.
• After a UCL group is created on the S2720-EI, S5720I-SI, S5720-LI, S5720S-LI, or S5720-SI, using the ucl-group command, the stack slot renumber command cannot be used to change the stack ID of a specified stack member switch.

When a member switch leaves a stack, if you specify the MAC address of the leaving switch as the stack MAC address and it does not rejoin the stack within the time specified by delay-time, the master switch changes the stack MAC address to its own MAC address.

The stack MAC address switchover delay time of any member switch in a stack is the same as that of the master switch.

If the value of the MAC address switchover timer is set to 0, no stack MAC address switchover will be performed.

This command can be used only after the stack function is enabled (default status).

Usage Scenario

Before upgrading a reliable stack with uplinks and downlinks working in redundancy mode, you can divide the stack into an active area and a backup area for redundancy. After an upgrade is started, member switches in the two areas are upgraded in sequence, shortening the service interruption duration and reducing the impact of the upgrade on the network.

Precautions

• Member switches in the active and backup areas form the entire stack. When dividing active and backup areas, note that:

  • The active and backup areas cannot have the same member switch, and both areas must have at least one member switch.
  • The backup area cannot contain the master switch of the stack.
  • Member switches in each area must be directly connected.

• After this command is run, the member switches with specified stack IDs join the backup area. The other member switches automatically join the active area.

• To ensure mutual backup, it is recommended that the two areas have similar quantities of member switches.

Before running this command, run the upgrade backup-area slot command to define the active and backup areas and ensure that all member switches in the stack are running the same system software and support smooth upgrades.

If an upgrade fails, error codes and displayed message help locate the cause. Table 3-58 lists the error codes and displayed messages in different upgrade failure scenarios.