Which three features of LAG-based redundancy influenced this decision?

An engineer must create data-link redundancy for the company’s Cisco Wireless LAN Controller. The engineer has decided to configure LAG-based redundancy instead of port-based redundancy. Which three features of LAG-based redundancy influenced this decision? (Choose three.)
A. Packets are always sent out on the same port they are received on.
B. All interface traffic passes as long as one port is up.
C. The same port has multiple untagged dynamics interfaces.
D. Interface connection to two separate nonstacked switches is available.
E. Full bandwidth of all links is available.
F. Ports are grouped into multiple LAGs.

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5 thoughts on “Which three features of LAG-based redundancy influenced this decision?

  1. The answer is ABD.

    “the controller sends packets out on the same port on which it received them.”
    “only one functional physical port is needed for the controller to pass client traffic.”
    “You cannot configure the controller’s ports into separate LAG groups. Only one LAG group is supported per controller.”
    https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_010100001.html
    “A better design distributes the individual links of the LAG across multiple line cards in a single physical switch, across a stack of switches, or across a pair of switches configured as a single logical switch.” On page 193 in Cert Guide. Virtual Switching Systems (VSS) can be nonstacked switches.

    1. Link Aggregation (LAG)
      The channel mode for the port-channel on the neighboring Catalyst switch or VSS connecting to the
      WLCs must be set to mode on (static).

      Enterprise Mobility 8.5 Design Guide

      LAG Mode
      For LAG scenarios, using VSS, stacked switch (3750/2960), or Nexus VPC, should work as long as the fragments of an IP packet are sent to the same port.

      Cisco Wireless LAN Controller (WLC) Configuration Best Practices

  2. You cannot configure the controller’s ports into separate LAG groups. Only one LAG group is supported per controller.
    Answer F is not correct. I am also going for ABE

  3. ABE is right.
    Only one LAG Group is supported per WLC, you can therefore connect a WLC only to one switch unless using VSS (Catalyst) or vPC (Nexus) technologies. When LAG is enabled, if a single link fails, traffic is automatically switched to the other links. Of course, LAG acts like any Port-channel and uses all links at a time. From the Cisco book for this exam (Chapter 9), it is mentioned that packets are sent out on the same port that they are received on.

    7
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