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| 3.9 |  | EtherChannel |
| 3.9.6 |  | Modifying port cost for EtherChannel groups |

If port cost is not specified, the spanning tree Port Cost is updated based on the current Port Costs of the channeling ports. However, if channel Port Cost is specified, the Port Costs of member ports in the channel are modified to reflect the new cost. This enables load balancing of VLAN traffic across multiple channels configured with trunking, because some VLANs in the channel have Port VLAN Cost values and the others have Port Cost values. This might not sound useful (or meaningful), but this allows, as an example, the configuration of VLAN traffic to load-balance between one EtherChannel connected to one core switch and another EtherChannel connected to another core switch.