Licensing Requirements and Limitations for Link Aggregation

Involved Network Elements

Other network elements are not required.

Licensing Requirements

Ethernet link aggregation is a basic feature of a switch and is not under license control.

Feature Support in V200R019C10

All models of S2720, S5700, and S6700 series switches support link aggregation.

For details about software mappings, visit Hardware Query Tool and search for the desired product model.

Feature Dependencies and Limitations

Precautions for configuring an Eth-Trunk

• Precautions for adding interfaces to an Eth-Trunk

  • An Eth-Trunk contains a maximum of 32 member interfaces on the S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-HI, S6730-H, S6730S-H, S6730-S, and S6730S-S, 16 member interfaces on the S5730-SI, S5730S-EI, S6720-LI, S6720S-LI, S6720-SI, and S6720S-SI, and 8 member interfaces on all other models. On the S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6730-H, S6730S-H, S6730-S, S6730S-S, S6720-EI, and S6720S-EI, the number of member interfaces in an Eth-Trunk can be flexibly configured. For details about the precautions, see Precautions for extending Eth-Trunk specifications.

  • If an interface of the local device is added to an Eth-Trunk, an interface of the remote device directly connected to the interface of the local device must also be added to the Eth-Trunk. Otherwise, communication between the two devices will fail.
  • Member interfaces of an Eth-Trunk cannot be an Eth-Trunk.

  • In versions earlier than V200R011C10, only interfaces with the same rate can join an Eth-Trunk. For example, GE electrical interfaces and GE optical interfaces can be added to the same Eth-Trunk interface. In V200R011C10 and later versions, after the mixed-rate link enable command is run, interfaces with different rates can be added to the same Eth-Trunk interface.

    When an Eth-Trunk performs load balancing calculation, the interface rate cannot be used as the calculation weight. When interfaces with different rates are added to the same Eth-Trunk, traffic is evenly load balanced among all the links. Therefore, the bandwidth of member interfaces is calculated by the minimum rate of the member interfaces in the Eth-Trunk. For example, when a GE interface and a 10GE interface are added to the same Eth-Trunk, the rate of the GE interface is used in calculation and the bandwidth of the Eth-Trunk is 2G.

  • Do not configure any member port of an Eth-Trunk as an observing port. If you must do so, ensure that the bandwidth of service traffic on this port and the bandwidth occupied by the mirrored traffic do not exceed the bandwidth limit of the port.

  • An Ethernet interface can be added to only one Eth-Trunk. To add an Ethernet interface to another Eth-Trunk, delete it from the original one first.
  • After an interface is added to an Eth-Trunk, the Eth-Trunk learns MAC address entries or ARP entries, but the member interface does not.

• Precautions for the networking on which an Eth-Trunk is configured

  • Both devices of the Eth-Trunk must use the same number of physical interfaces, duplex mode, and flow control mode.
  • Both devices of an Eth-Trunk must use the same link aggregation mode.
  • Before deleting an Eth-Trunk, delete member interfaces from the Eth-Trunk.

  • On member interfaces, some commands (for example, port link-type access) and static MAC addresses cannot be configured. Otherwise, errors will be reported.

  • In fiber to the x (FTTx) scenarios of MANs, PPPoE is often used for Internet access. If switches use link aggregation, when traffic is aggregated, ensure that PPPoE packets are load balanced. In such scenarios, the following models are recommended: S5700-EI, S5700-HI, S5710-EI, S5710-HI, S5720-EI, S5720-HI, S5730-HI, S5730S-EI, S5730-SI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6700-EI, S6720-EI, S6720-HI, S6720-LI, S6720S-EI, S6720S-LI, S6720S-SI, S6720-SI, S6730-H, S6730S-H, S6730-S, and S6730S-S.

Configuration precautions in different scenarios

Precautions for extending Eth-Trunk specifications

• For the S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6730-H, S6730S-H, S6730-S, and S6730S-S along with the S6720-EI and S6720S-EI running V200R009 and later versions, you can run the assign trunk { trunk-group group-number | trunk-member member-number }^* command to configure the maximum number of Eth-Trunks and maximum number of member interfaces in each Eth-Trunk.

• By default, if the value of member-number configured for an Eth-Trunk using the assign trunk { trunk-group group-number | trunk-member member-number }^* command is larger than 16 on the S6720-EI and S6720S-EI or larger than 32 on the S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6730-H, S6730S-H, S6730-S, and S6730S-S, known unicast packets are load balanced using the enhanced mode, and BUM packets are load balanced based on their source and destination MAC addresses. Known unicast packets must be load balanced using the enhanced mode (the load balancing mode can be configured using the load-balance command). Otherwise, packet loss or uneven load balancing may occur.

• After the Eth-Trunk specifications are modified, save the configuration and restart the switch to make the modification take effect.

• If you use the assign trunk command to modify Eth-Trunk specifications, the existing Eth-Trunk configuration will become invalid or be lost. Exercise caution when you run the assign trunk command. When the configured Eth-Trunk specifications are reduced and the Eth-Trunks that exceed the specifications are configured, the configuration of excess Eth-Trunks is invalid.