# Link aggregation

### 1. Function Overview

Link aggregation is a function used to combine multiple LAN/SFP ports that connect network devices, and handle them as a single logical interface.
Link aggregation is a technology that is useful when multiple communications occur. Communications can be distributed by using a load balance function within the combined lines.
If one LAN/SFP port fails within the lines that were combined using link aggregation, and communications cannot be made, the other ports will continue communicating.

- Link aggregation function overview

The link aggregation functions in this network switch are shown below.

- Link aggregation functions

  Functions provided | Contents
  --- | ---
  Static link aggregation | Link aggregation for manually setting the LAN/SFP ports to combine. This begins to operate as a logical interface when the LAN/SFP ports link up.
  LACP link aggregation | Link aggregation that uses LACP to combine the LAN/SFP ports. This begins to operate as a logical interface when the negotiation via LACP between the connected devices is successful.

### 2. Definition of Terms Used

LACP

Abbreviation for “Link Aggregation Control Protocol”. This is a technology standardized in IEEE802.1AX-2008,
and is also called EtherChannel.

- IEEE802.1AX-2008 Link Aggregation Task Force

Load balance

This is a function to distribute forwarded frames between the LAN/SFP ports that are associated with the logical interface.
As a distribution rule, the L2/L3/L4 information within frames is used.

### 3. Function Details

#### 3.1. Static/LACP link aggregation: common specifications

The common specifications for the static/LACP link aggregation functions of this network switch are shown below.

1. The link aggregation on this network switch can be defined for 127 interfaces, including both static and LACP (126 interfaces for stacks).
   A single logical interface can be associated with up to eight LAN/SFP ports.

2. The settings shown below must be the same for each of the LAN/SFP ports contained within.

   - Port mode (access/trunk [including native VLAN settings])

   - Associated VLAN

   - QoS trust mode (including port priority and default CoS settings)

   - Loop detection (enables/disables loop detection and enables/disables port blocking)

3. Executes the following process when a LAN/SFP port is associated with a logical interface.

   - LAN/SFP ports that are linked up will be linked down.
     The logical interface’s default value will be set to shutdown, in order to safely integrate the logical interface into the system.

   - MSTP settings will be discarded and will revert to their defaults.
     When dissociating a LAN/SFP port from the logical link, the MSTP settings for the relevant port will revert to their defaults as well.

4. The following operations can be performed for the logical interface.

   - Add description text (description command)

   - Enable/disable the interface (shutdown command)

5. Another LAN/SFP port cannot be associated with a logical interface in operation.
   To associate a LAN/SFP port, make sure to shut down the logical interface before associating.

6. LAN/SFP ports that are associated with a logical interface that is in operation cannot be removed.
   When dissociating a LAN/SFP port, make sure to shut down the logical interface before dissociating.
   LAN/SFP ports that have been dissociated from a logical interface will be in shutdown mode. Enable the ports as necessary (using “no shutdown”).

7. Load balance settings can be made on the logical interface. The rules that can be set for this are shown below.
   The default value when defining a logical interface is the destination/source MAC address.

   - Destination MAC address

   - Source MAC address

   - Destination/source MAC address

   - Destination IP address

   - Source IP address

   - Destination/source IP address

   - Destination port number

   - Source port number

   - Destination/source port numbers

#### 3.2. Static link aggregation

The operating specifications for static link aggregation are shown below.

1. An interface number from 1–96 can be assigned to the static logical interface.

2. Use the static-channel-group command to associate a LAN/SFP port with a static logical link interface.

   - When associating a LAN/SFP port with an interface number for which there is no static logical interface, a new logical interface will be generated.

   - When the associated port no longer exists as a result of removing a LAN/SFP port from a static logical interface, the relevant logical interface will be deleted.

3. Use the show static-channel-group command to show the static logical interface’s status.

#### 3.3. LACP link aggregation

The operating specifications for LACP link aggregation are shown below.
Refer to “3.1 Static/LACP link aggregation: common specifications” for the common specifications of static link aggregation.

1. An interface number from 1–127 can be assigned to the LACP logical interface.

2. Use the channel-group command to associate a LAN/SFP port with an LACP logical link interface.

   - When associating an LAN/SFP, specify the following operating modes. (It is recommended to specify “active mode”.)

     - Active mode
       The LACP frame will be voluntarily transmitted, and negotiation with the opposing device’s port will begin.

     - Passive mode
       The LACP frame will not be voluntarily transmitted, but will instead be transmitted when a frame is received from the opposing device.

   - When associating a LAN/SFP port with an interface number for which there is no LACP logical interface, a new logical interface will be generated.

   - When the associated port no longer exists as a result of removing a LAN/SFP port from an LACP logical interface, the relevant logical interface will be deleted.

3. The parameters that influence the operations of the LACP logical interface are shown below.

   - LACP timeout
     LACP timeout indicates the down time that was determined, when an LACP frame has not been received from the opposing device.
     Specify either “Long” (90 sec.) or “Short” (3 sec.) using the lacp timeout command.
     The LACP timeout value is stored in the LACP frame and transmitted to the opposing device.
     The opposing device that received the frame will transmit the LACP frames it has stored at intervals equaling 1/3 of the LACP timeout value.
     The default value when the logical interface is generated is “Long (90 sec.)”.

   - LACP system priority
     The LACP system priority is used when deciding which device will control the logical interface, when communicating with the opposing device. The LACP system priority and MAC address values (in combination referred to as the system ID) are exchanged with the interfacing device and the device with the highest LACP system priority level is assigned control. If both devices have the same LACP system priority level, the device with the lower MAC address is assigned control.
     The device assigned control determines which LAN or SFP ports associated with the logical interface are enabled (activated).
     LACP system priority values within the range 1 to 65535 can be specified using the lacp system-priority command, where the lower the setting value, the higher the priority level. The default value when the logical interface is generated is set to 32768 (0x8000).

   - LACP port priority
     LACP port priority is used to control active/standby for the LAN/SFP ports that are associated with the logical interface. If more than the maximum number of LAN/SFP ports (8 ports) is associated with a logical interface, then the port status is controlled based on the LACP port priority.
     If ports have the same LACP port priority, then the port with the lower port number is given priority. If a stack is configured, port numbers for network switches with a lower stack ID are prioritized regardless of the port number. For example, port 1.10 is prioritized over port 2.1.
     LACP port priority values within the range 1 to 65535 can be specified using the lacp port-priority command, where the lower the setting value, the higher the priority level. The default LACP port priority setting is 32768 (0x8000).

4. LAN/SFP ports in half-duplex communication mode do not support LACP link aggregation.

   - Half-duplex LAN/SFP ports that are associated with an LACP logical interface are never activated.

5. The following describes actions that occur if LAN/SFP ports with different communication speeds are located on the same logical interface.
   To configure link aggregation with a mixture of different communication speeds, enable multi-speed link aggregation.

   - Actions if multi-speed link aggregation is enabled (lacp multi-speed enable)

     - Activate all associated ports (up to a maximum 8 ports), regardless of communication speed.

     - Load balancing treats all associated ports as equivalent.

       - That increases the risk of a communication overflow occurring at a slow associated port.

       - If there are more than the maximum 8 LAN/SFP ports, higher priority values are assigned to faster associated ports.

     - If the other device cannot accept a different communication speed, then both interacting devices mutually exchange lists of associated ports and activate associated port that can be used by both devices.
       Consequently, the process is limited by the device that cannot accept different communication speeds.

   - Actions if multi-speed link aggregation is disabled (lacp multi-speed disable)

     - Only associated ports with a communication speed the same as the port first linked up are activated.

       - Other ports with a different communication speed remain in standby mode.

       - If auto negotiation is enabled, only associated ports with a communication speed that is the same as the negotiation result of the first negotiation will be activated.

     - If links go down for all the ports first linked up, then the link will go down for the LACP logical interface as well.

6. The show etherchannel command can be used to check the LACP logical interface status.

   - The show etherchannel status detail command can be used to check the activation status of associated ports.

7. LACP link aggregation is used even if a stack is configured. However, the following restriction applies.

   - A total of 126 logical interfaces can be defined for both static and LACP.

### 4. Related Commands

Related commands are indicated below.
For details on the commands, refer to the Command Reference.

Operations | Operating commands
--- | ---
Set the static logical interface | static-channel-group
Show the static logical interface status | show static-channel-group
Set the LACP logical interface | channel-group
Set LACP system priority | lacp system-priority
Show LACP system priority | show lacp sys-id
Set LACP multi-speed link aggregation | lacp multi-speed
Set LACP timeout | lacp timeout
Clear LACP packet counter | clear lacp
Show LACP packet counter | show lacp counters
Show the status of the LACP logical interface | show etherchannel
Set load balance function rules | port-channel load-balance

### 5. Examples of Command Execution

#### 5.1. Set the static logical interface

In this example, we will set link aggregation to use four LAN ports, in order to communicate between network switches.

- Static link aggregation is set to static.
  The logical interface numbers are as follows: Switch A: #2, switch B: #5.

- The LAN ports associated with the logical interface are all access ports, and are associated with the VLAN #1000.

  1. Define [switch A] VLAN #1000, and associate it with LAN ports (#1, #2, #3, #4, #8).
     Together with this, associate LAN ports (#1, #2, #3, #4) with logical interface #2.

         Yamaha(config)#vlan database
         Yamaha(config-vlan)#vlan 1000 (1)
         Yamaha(config-vlan)#exit
         Yamaha(config)#interface port1.8 (2)
         Yamaha(config-if)#switchport access vlan 1000 (3)
         Yamaha(config-if)#interface port1.1 (4)
         Yamaha(config-if)#switchport access vlan 1000 (5)
         Yamaha(config-if)#static-channel-group 2 (6)
         Yamaha(config-if)#interface port1.2
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 2
         Yamaha(config-if)#interface port1.3
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 2
         Yamaha(config-if)#interface port1.4
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 2

     1 | Define VLAN #1000
     2 | Set LAN port #8
     3 | Set the port as access port and associate it with VLAN #1000
     4 | Set LAN port #1
     5 | Set the port as access port and associate it with VLAN #1000
     6 | Associate it with logical interface #2

  2. Confirm the setting status of [switch A] logical interface #2.

         Yamaha#show static-channel-group
         % Static Aggregator: sa2
         % Member:
            port1.1
            port1.2
            port1.3
            port1.4

  3. Define [switch B] VLAN #1000, and associate it with LAN ports (#1, #2, #3, #4, #7).
     Together with this, associate LAN ports (#1, #2, #3, #4) with logical interface #5.

         Yamaha(config)#vlan database
         Yamaha(config-vlan)#vlan 1000
         Yamaha(config-vlan)#exit
         Yamaha(config)#interface port1.7
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#interface port1.1
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 5
         Yamaha(config-if)#interface port1.2
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 5
         Yamaha(config-if)#interface port1.3
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 5
         Yamaha(config-if)#interface port1.4
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)#static-channel-group 5

  4. Confirm the setting status of [switch B] logical interface #5.

         Yamaha#show static-channel-group
         % Static Aggregator: sa5
         % Member:
            port1.1
            port1.2
            port1.3
            port1.4

  5. Enable [switch A] logical interface.

         Yamaha(config)#interface sa2 (1)
         Yamaha(config-if)#no shutdown (2)

     1 | Set logical interface #2
     2 | Enable the logical interface

  6. Enable [switch B] logical interface.

         Yamaha(config)#interface sa5 (1)
         Yamaha(config-if)#no shutdown (2)

     1 | Set logical interface #5
     2 | Enable the logical interface

  7. Confirm the setting status of [switch A] logical interface.

         Yamaha#show interface sa2
         Interface sa2
           Link is UP (1)
           Hardware is AGGREGATE
           ifIndex 4502, MRU 1522
           Vlan info :
             Switchport mode        : access
             Ingress filter         : enable
             Acceptable frame types : all
             Default Vlan           : 1000
             Configured Vlans       : 1000
           Interface counter:
             input  packets          : 1020
                    bytes            : 102432
                    multicast packets: 1020
             output packets          : 15
                    bytes            : 1845
                    multicast packets: 15
                    broadcast packets: 0

     1 | Enabled

  8. Confirm the setting status of [switch B] logical interface.

         Yamaha#show interface sa5
         Interface sa5
           Link is UP
           Hardware is AGGREGATE
           ifIndex 4505, MRU 1522
           Vlan info :
             Switchport mode        : access
             Ingress filter         : enable
             Acceptable frame types : all
             Default Vlan           : 1000
             Configured Vlans       : 1000
           Interface counter:
             input  packets          : 24
                    bytes            : 2952
                    multicast packets: 24
             output packets          : 2109
                    bytes            : 211698
                    multicast packets: 2109
                    broadcast packets: 0

#### 5.2. Setting the LACP logical interface

In this example, we will set link aggregation to use four LAN ports, in order to communicate between network switches.

- Use LACP for link aggregation.
  The logical interface numbers are as follows: Switch A: #10, switch B: #20.
  Set the switch A logical interface to active status, and the switch B logical interface to passive status.

- The LAN ports associated with the logical interface are all access ports, and are associated with the VLAN #1000.

- For load balance, set the destination/source IP address.

  1. Define [switch A] VLAN #1000, and associate it with LAN ports (#1, #2, #3, #4, #8).
     Together with this, associate LAN ports (#1, #2, #3, #4) in active status with the logical interface #10.
     The logical interface at this point in time will be in shutdown mode.

         Yamaha(config)#vlan database
         Yamaha(config-vlan)#vlan 1000 (1)
         Yamaha(config-vlan)#exit
         Yamaha(config)#interface port1.8
         Yamaha(config-if)#switchport access vlan 1000 (2)
         Yamaha(config-if)#interface port1.1
         Yamaha(config-if)#switchport access vlan 1000 (3)
         Yamaha(config-if)#channel-group 10 mode active (4)
         Yamaha(config-if)#interface port1.2
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)# channel-group 10 mode active
         Yamaha(config-if)#interface port1.3
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)# channel-group 10 mode active
         Yamaha(config-if)#interface port1.4
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)# channel-group 10 mode active

     1 | Define VLAN #1000
     2 | Set the port as access port and associate it with VLAN #1000
     3 | Set the port as access port and associate it with VLAN #1000
     4 | Associate the port with logical interface #10 in active state

  2. Confirm the setting status of [switch A] logical interface #10.

         Yamaha#show etherchannel
         % Lacp Aggregator: po10
         % Member:
            port1.1
            port1.2
            port1.3
            port1.4
         Yamaha#show lacp sys-id (1)
         % System 8000,00-a0-de-ae-b9-1f
         Yamaha#show interface po10
         Interface po10
           Link is DOWN (2)
           Hardware is AGGREGATE
           ifIndex 4610, MRU 1522
           Vlan info :
             Switchport mode        : access
             Ingress filter         : enable
             Acceptable frame types : all
             Default Vlan           : 1000
             Configured Vlans       : 1000
           Interface counter:
             input  packets          : 0
                    bytes            : 0
                    multicast packets: 0
             output packets          : 0
                    bytes            : 0
                    multicast packets: 0
                    broadcast packets: 0

     1 | Check that the LACP system ID is set to the default value (0x8000).
     2 | Link is in down

  3. Define [switch B] VLAN #1000, and associate it with LAN ports (#1, #2, #3, #4, #7).
     Together with this, associate LAN ports (#1, #2, #3, #4) in passive status with the logical interface #20.
     The logical interface at this point in time will be in shutdown mode.

         Yamaha(config)#vlan database
         Yamaha(config-vlan)#vlan 1000 (1)
         Yamaha(config-vlan)#exit
         Yamaha(config)#interface port1.7
         Yamaha(config-if)#switchport access vlan 1000 (2)
         Yamaha(config-if)#interface port1.1
         Yamaha(config-if)#switchport access vlan 1000 (3)
         Yamaha(config-if)#channel-group 20 mode passive (4)
         Yamaha(config-if)#interface port1.2
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)# channel-group 20 mode passive
         Yamaha(config-if)#interface port1.3
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)# channel-group 20 mode passive
         Yamaha(config-if)#interface port1.4
         Yamaha(config-if)#switchport access vlan 1000
         Yamaha(config-if)# channel-group 20 mode passive

     1 | Define VLAN #1000
     2 | Set the port as access port and associate it with VLAN #1000
     3 | Set the port as access port and associate it with VLAN #1000
     4 | Associate the port with logical interface #20 in passive state

  4. Confirm the setting status of [switch B] logical interface #20.

         Yamaha#show etherchannel
         % Lacp Aggregator: po20
         % Member:
            port1.1
            port1.2
            port1.3
            port1.4
         Yamaha#show lacp sys-id (1)
         % System 8000,00-a0-de-ae-b8-7e
         Yamaha#show interface po20
         Interface po20
           Link is DOWN (2)
           Hardware is AGGREGATE
           ifIndex 4620, MRU 1522
           Vlan info :
             Switchport mode        : access
             Ingress filter         : enable
             Acceptable frame types : all
             Default Vlan           : 1000
             Configured Vlans       : 1000
           Interface counter:
             input  packets          : 0
                    bytes            : 0
                    multicast packets: 0
             output packets          : 0
                    bytes            : 0
                    multicast packets: 0
                    broadcast packets: 0

     1 | Check that the LACP system ID is set to the default value (0x8000).
     2 | Link down state

  5. Set the load balance of [switch A] to the destination/source IP address, and enable the interface.

         Yamaha(config)#port-channel load-balance src-dst-ip (1)
         Yamaha(config)#interface po10 (2)
         Yamaha(config-if)#no shutdown (3)

     1 | Set the load balance
     2 | Set logical interface #10
     3 | Enable the logical interface

  6. Set theload balance of [switch B] to the destination/source IP address, and enable the interface.

         Yamaha(config)#port-channel load-balance src-dst-ip (1)
         Yamaha(config)#interface po20 (2)
         Yamaha(config-if)#no shutdown (3)

     1 | Set the load balance
     2 | Set logical interface #20
     3 | Enable the logical interface

  7. Confirm the setting status of [switch A] logical interface.
     Link up and confirm whether frames are being sent and received.

         Yamaha#show interface po10
         Interface po10
           Link is UP
           Hardware is AGGREGATE
           ifIndex 4610, MRU 1522
           Vlan info :
             Switchport mode        : access
             Ingress filter         : enable
             Acceptable frame types : all
             Default Vlan           : 1000
             Configured Vlans       : 1000
           Interface counter:
             input  packets          : 560
                    bytes            : 58239
                    multicast packets: 560
             output packets          : 98
                    bytes            : 12474
                    multicast packets: 98
                    broadcast packets: 0
         Yamaha#
         Yamaha#show lacp-counter
         % Traffic statistics
         Port       LACPDUs         Marker         Pckt err
                 Sent    Recv    Sent    Recv    Sent    Recv
         % Aggregator po10 , ID 4610
         port1.1      50      47      0       0       0       0
         port1.2      49      46      0       0       0       0
         port1.3      49      46      0       0       0       0
         port1.4      49      46      0       0       0       0

  8. Confirm the setting status of [switch B] logical interface.
     Link up and confirm whether frames are being sent and received.

         Yamaha#show interface po20
         Interface po20
           Link is UP
           Hardware is AGGREGATE
           ifIndex 4620, MRU 1522
           Vlan info :
             Switchport mode        : access
             Ingress filter         : enable
             Acceptable frame types : all
             Default Vlan           : 1000
             Configured Vlans       : 1000
           Interface counter:
             input  packets          : 78
                    bytes            : 9914
                    multicast packets: 78
             output packets          : 438
                    bytes            : 45604
                    multicast packets: 438
                    broadcast packets: 0
         Yamaha#
         Yamaha#show lacp-counter
         % Traffic statistics
         Port       LACPDUs         Marker         Pckt err
                 Sent    Recv    Sent    Recv    Sent    Recv
         % Aggregator po20 , ID 4620
         port1.1      55      57      0       0       0       0
         port1.2      54      56      0       0       0       0
         port1.3      54      56      0       0       0       0
         port1.4      54      56      0       0       0       0

### 6. Points of Caution

- A host port that is associated with a private VLAN cannot be aggregated as a link aggregation logical interface.

- If access list settings exist for the received frame of a LAN/SFP port, the ports cannot be aggregated as a link aggregation logical interface.

### 7. Related Documentation

- LAN/SFP Port Control: Basic Interface Settings

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