Mirroring and sFlow

The mirroring feature (when mirroring received traffic) and the sFlow sampling feature both require the receive (rx) capability of a given port. If both features are configured and enabled to use the receive capability on the same port, only one of the features can perform its task.

This interaction does not affect transmit (tx) mirroring because sFlow does not use the transmit (tx) capability of a port.

Behavior if sFlow is enabled and mirror enable is attempted

If sFlow is enabled on a port and a mirroring session specifies the same port as a source of received traffic (the source is configured with a direction of rx or both):

  • The attempt to enable the mirroring session fails and an error is returned.

  • To enable the mirroring session, first you must disable sFlow on that port.

Behavior if mirroring is enabled and sFlow enable is attempted

If a mirroring session specifies a port as a source of received traffic (the source is configured with a direction of rx or both), and you attempt to enable sFlow on the same port:

  • Mirroring on that port continues.

  • No error or warning message is returned when sFlow is enabled, but sFlow sampling on that port does not occur.

    When sFlow is enabled on a port but sampling is not occurring, the show sflow <INTERFACE-NAME> command shows that sFlow is enabled but shows a value of 0 (zero) for the number of samples.

  • To activate sFlow sampling on that port, you must do the following:

    1. Disable the mirroring session on the port.

    2. Disable sFlow on the port.

    3. Enable sFlow on the port.

Behavior when the startup configuration has both sFlow and rx mirroring enabled on the same port

If the startup configuration has the same port configured with both sFlow enabled and as a source of received traffic in an enabled mirroring session:

  • During a boot or management module failover operation, it is not possible to predict whether the receive capability of the port will be assigned to the sFlow feature or to the mirroring feature.

  • To ensure that the feature that you want is used on a specific port, after the boot operation or management module failover operation completes, disable both features on that port and then enable the feature you want to use.