4A0-105: Nokia Virtual Private LAN ServicesDemo

By Nokia · Question Mode

QuestionQ33

VPLS loop avoidance

Which of the following statements are true when ports have the IEEE 802.3ah Loopback Control feature configured?

Choose three
  • A The loopback control PDU instructs the remote port to enter loopback mode.
  • B Putting a port in loopback does not affect customer data flow
  • C Both ports must rediscover the OAM capabilities of each other once the port is put back into service.
  • D Both ports must still send Information PDUs to avoid going back to discovery mode.
  • E When a port is in loopback mode, service mirroring will still work if it is a mirror-source or mirror-destination.
  • F All packets, except for information PDUs, are looped back.
Explanation

A Loopback Control OAM PDU directs the remote OAM peer to enter loopback. Information OAM PDUs must continue during loopback to preserve the OAM session, while traffic subject to the loopback is returned on the same port. Loopback interrupts ordinary service forwarding, does not require a fresh capability-discovery exchange merely when it is disabled, and prevents service mirroring when the port is a mirror source or destination.

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