Implementing Link Aggregation on a Cisco Wireless LAN Controller

D

Link Aggregation, also known as EtherChannel or port-channel, allows multiple physical ports to be combined into a single logical port, increasing the bandwidth and providing redundancy in case of link failure. Implementing Link Aggregation on a Cisco Wireless LAN Controller (WLC) involves the following steps:

Step 1: Configure the physical ports

Firstly, the physical ports that will be used for Link Aggregation must be configured. The WLC supports Link Aggregation with Fast Ethernet and Gigabit Ethernet ports. The physical ports can be configured using the WLC GUI or CLI.

Step 2: Configure the EtherChannel

After configuring the physical ports, the EtherChannel must be created. The EtherChannel can be configured using either the WLC GUI or CLI. When configuring the EtherChannel, the following options are available:

• Mode: The EtherChannel mode determines how the WLC negotiates with the other end of the link. The two available modes are "active" and "passive". In "active" mode, the WLC initiates the negotiation and sends LACP packets to the other end of the link. In "passive" mode, the WLC waits for the other end of the link to initiate the negotiation.

• Load balancing: The EtherChannel load balancing method determines how traffic is distributed across the physical ports. The WLC supports four load balancing methods: "src-dst-ip", "src-dst-mac", "src-dst-port", and "src-ip".

• Minimum links: The minimum number of physical links required to form the EtherChannel. The default value is two.

• Link status: The link status of the EtherChannel can be checked using the WLC GUI or CLI. The link status indicates whether the physical links are up or down.

Step 3: Verify the EtherChannel configuration

Once the EtherChannel is configured, it is important to verify that the configuration is correct. This can be done by checking the link status of the EtherChannel using the WLC GUI or CLI.

Answer options:

A. The EtherChannel must be configured in "mode active". This answer option is correct. The EtherChannel mode determines how the WLC negotiates with the other end of the link. In "active" mode, the WLC initiates the negotiation and sends LACP packets to the other end of the link.

B. When enabled, the WLC bandwidth drops to 500 Mbps. This answer option is incorrect. Enabling Link Aggregation on a Cisco WLC does not affect the bandwidth of the WLC.

C. To pass client traffic, two or more ports must be configured. This answer option is correct. To pass client traffic, two or more physical ports must be combined into an EtherChannel.

D. One functional physical port is needed to pass client traffic. This answer option is incorrect. One functional physical port is not sufficient to pass client traffic when Link Aggregation is enabled on a Cisco WLC.