Understanding Loopback Testing

Layer 1–4 loopbacks (MAC address, IP address & port swap) permit remote QoS testing for Ethernet, IP/MPLS and triple-play services. Loopbacks can be established by any of the following combination of parameters:

• Source or destination address
• TCP/UDP port
• Service level

Loopbacks can be performed in-band or out-of-band, so customer traffic continues to flow while tests are performed on selected streams.

The unit allows for two types of loopback:

• Local (or private) loopback: Loops back all traffic matching the type of loopback in the setup (Iometrix L1, EXFO L2, EXFO L3, Custom).
• Remotely controlled loopback: Loops back traffic and is initiated upon the reception of a predefined frame type (JDSU/Acterna™, Sunrise™).