Loopback

This topic describes how to use the VLAN ID-based loopback detection function to detect loop services in E-LAN services.

Navigation Path

For RTN NEs, in the NE Explorer, click the NE and choose Configuration > Ethernet Service Management > E-LAN Service. Then click the Loopback tab.

NOTE:

Creation of MEPs is not a prerequisite for service loopback detection.
Service loopback detection and STP/RSTP/MSTP are mutually exclusive.
If an E-LAN service is mounted to a port that functions as the east and west ERPS port, loopback tests cannot be performed on the service.

Buttons

Button	Description
Start	Clicks this button after selecting a port to open the detection startup window.
Service Status List	Clicks this button to view the service shutdown state. Disabled services during loopback detection in the list can be enabled.
Enable	Enables services with Disable state.

Parameters

**Table 1** Loopback
Field	Value	Description
Port	For example: slot number-board name-port number (port name)	Indicates the name of a port.
PW ID	For example: 45	Indicates the PW ID.
QinQ Link ID	For example: 45	Indicates the QinQ link ID.
Available C-VLANs	1 to 4094	Indicates the range of VLAN IDs.
VLANs/CVLAN	1 to 4094	VLANs/CVLAN displays the VLAN ID of a loopback service. Loopback detection can be performed for only one service one time. Its value must be within the Available CVLANs value,or be blank. NOTE: If this parameter is left blank, loopback can be performed on VLAN-free services.
Packet Timeout Period(s)	3 to 10	Loopback detection stops if no loopback detection packets are received until Packet Timeout Period(s) expires.
Packet Length	64	Indicates the length of a detection packet.
VLAN Packet Sending Interval(s)	0.2	Indicates the interval for sending detection packets between VLANs.
Disable Service When Loopback Is Detected	Yes, No	Specifies whether to automatically disable services if loopback is detected.
Packet Forwarding Priority	0 to 7	Specifies the packet forwarding priority. A larger value indicates a higher priority.
Loopback Packet Sent From(UNI)	For example: slot number-board name-port number (port name)	Indicates the UNI port that initiates loopback detection.
CVLAN	1 to 4094	Indicates the C-VLAN that initiates loopback detection.
Detection Result	-	Indicates loopback detection results.
Service Status	Enable, Disable	Indicates the status of the service that initiates loopback detection.
Loopback Packet Received By(UNI)	For example: slot number-board name-port number (port name)	Indicates the UNI port that receives loopback detection.
Loopback Packet Received By(NNI)	For example: slot number-board name-port number (port name)	Indicates the NNI port that receives loopback detection.
Intermediate NE List	For example: NE(9-123)	Indicates the intermediate NE list which the detection path passes through.
VLAN	1 to 4094	Indicates the VLAN that initiates loopback detection.