Setting Up and Enabling Loopbacks

Updated on 25 Jan 2024
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Follow the steps below to set up a local loopback:

Define filters for capturing traffic (required for custom loopbacks only), "Defining Filters".
Create an OAM instance, see "Setting Up an OAM Instance".
Create the loopback, as explained in the following procedure.

To set up a local loopback

Access the page OAM ►Loopback
A summary of all OAM instances that have been set up is displayed.
Click the instance's Name to edit its settings.
Enter values in the required fields (located at the top part of the page), then click Apply.
Note: When selecting Loopback Enable and/or Drop Opposite Traffic, the following message will be displayed "Configuration changes are service affecting. Are you sure you want to proceed?". Click OK to proceed with your changes or Cancel to go back to the previous screen.

For more information on specific parameters, refer to the following table.

Note: Only the fields listed in the following table are required for a local loopback. Leave all other fields at their default settings.

Loopback (Loopback ►Configuration)

Parameter	Description
Name	The OAM instance name as defined in the OAM ConfigurationLoopback ►Configuration page
Port	Make a selection from the drop-down list to indicate the port on which the loopback will be created.
State	The current state of the loopback. An enabled loopback may not necessarily loop back traffic; this depends on the location setting. An instance enabled for a remotely controlled loopback is not shown in this field.
Lpbk Mode	When the loopback control logic is enabled, this field displays the loopback mode that has been selected for the given port. This parameter is always set to Private. A value of Private indicates that either no 802.3ah loopback is active or that a private (i.e. proprietary) loopback has been configured. When using the private loopback mode, you can select filters or preset OEM loopback types, which creates an in-service loopback that allows other traffic to flow through.
Location	Indicates whether the loopback is controlled locally or remotely. Once enabled, a local loopback immediately applies the loopback to the unit as programmed. An enabled remote loopback instructs the unit to transmit a loopback request to its OAM partner.
Loopback Enable	Select this box to activate a locally controlled loopback, then choose a Type from the drop-down list. Note: Do not select this box to activate a remote loopback. Instead, indicate the type of remote device in the Remote Loopback Enable section below.
Type	Type may be one of the following: Iometrix L1: Iometrix cNode level 1. Loops back all frames that have a destination address equal to 00:30:79:FF:FF:FF Exfo L2: Loops back all frames that have a source MAC OUI equal to 00:03:01. Exfo L3: Loops back all UDP echo service packets. AnaCise L2: Loops back all frames that have a source MAC OUI equal to 00:18:75. AnaCise L3: Loops back all UDP echo service packets. Custom: Loops back all traffic that matches the user-defined filter (Filter Type and related fields). 802.3ah: Indicates that a loopback has been activated on the port as a result of receiving a 802.3ah OAM PDU. At the same time, the Loopback State field is updated to Enabled.
Persistent	Enables the loopback at start-up time. Note: This option only applies to locally controlled loopbacks with no timeout.
Filter Type	The type of filter to be applied to the loopback traffic: L2 Filter IPv4 Filter IPv6 Filter
L2 Filter	The L2 filter to be applied to loopback traffic, if the filter type is L2 Filter.
IPv4 Filter	The IPv4 filter to be applied to loopback traffic, if the filter type is IPv4 Filter.
IPv6 Filter	The IPv6 filter to be applied to loopback traffic, if the filter type is IPv6 Filter.
Actions	The action may be one or more of the following: Swap MAC Addresses: Swaps the source and destination MAC addresses. Swap IP Addresses: Swaps the source and destination IP addresses. Swap TCP/UDP Ports: Swaps the source and destination TCP/UDP ports.
Loopback Timeout	Number of minutes for the loopback to remain enabled. When the timeout expires, the loopback is automatically terminated.

Remote Loopback Enable

Parameter	Description
JDSU/Acterna™	Select this box to indicate that this remote loopback will be controlled by a JDSU/Acterna™ device.
Enable Discovery Loop Commands	Select this box to indicate that this remote loopback will accept JDSU/Acterna™ discovery loopback commands.
Sunrise™	Select this box to indicate that this remote loopback will be controlled by a Sunrise™ device. The unit supports tests on Layer 2 and Layer 3.
VeEX™	Select this box to indicate that this remote loopback will be controlled by a VeEX™ device. The unit supports tests on Layer 2, Layer 3 and Layer 4.
OAM 802.3ah	Select this box to indicate that this remote loopback will be controlled by a device that supports the OAM 802.3ah protocol.
Accept Tagged Loopback Commands	Select this box to indicate that this remote loopback will accept tagged loopback commands. This option is only valid for untagged OAM instances. Tagged OAM instances only accept loopback commands from a specific VLAN.

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