When an explicit failover order has been configured on a virtual switch with multiple uplinks, what determines

When an explicit failover order has been configured on a virtual switch with multiple uplinks, what determines which uplink is used when a failover event occurs?

A.
The first available uplink that reports a positive link state

B.
The reported uptime for the surviving uplinks

C.
The next available uplink on the list

D.
The uplink with the shortest route

7 Comments on “When an explicit failover order has been configured on a virtual switch with multiple uplinks, what determines

  1. adam turner says:

    it seems to be an error in the question. most instances of this question state “when explicit failover has _not_ beenconfigured”,aka rolling failover, which would make the longest uptime uplink as the selection.

    when explicit failover _has_ been selected, the vmworld 2006 networking presentation states “the highest priority uplink which is up”.

    Technically in the case of C, there would be a possibility that an uplink without being up would be selected, making A “more correct”.

  2. moors says:

    Answer B seems to be the closest.

    With the Explicit Failover Order load balancing algorithm in effect, you are essentially not load balancing at all! Explicit failover will utilize, for all traffic, the “highest order” uplink from the list of Active pNICs that passes the “I’m alive” test. What does the “highest order” mean? Well, it’s simply the pNIC that has been up the longest!

    http://kensvirtualreality.wordpress.com/2009/04/05/the-great-vswitch-debate%E2%80%93part-3/

  3. CarlosJara says:

    When an explicit failover order has been configured on a virtual switch with multiple uplinks
    -> The next available uplink on the list

    When an explicit failover order has NOT been configured on a virtual switch with multiple uplinks
    -> The reported uptime for the surviving uplinks

  4. Antti says:

    Based on the 5.1 documentation I would say the correct answer is A:

    Use explicit failover order — Always use the highest order uplink from the list of Active adapters which passes failover detection criteria.

    Network Failover Detection

    Specify the method to use for failover detection.
    ■ Link Status only – Relies solely on the link status that the network adapter provides. This option detects failures, such as cable pulls and physical switch power failures, but not configuration errors, such as a physical switch port being blocked by spanning tree or that is misconfigured to the wrong VLAN or cable pulls on the other side of a physical switch.
    ■ Beacon Probing – Sends out and listens for beacon probes on all NICs in the team and uses this information, in _addition_ to link status, to determine link failure. This detects many of the failures previously mentioned that are not detected by link status alone.


Leave a Reply

Your email address will not be published. Required fields are marked *