loopback

loopback (Aggregated Ethernet, Fast Ethernet, and Gigabit Ethernet)

Syntax

(loopback | no-loopback);

Hierarchy Level

[edit interfaces interface-name aggregated-ether-options],
[edit interfaces interface-name fastether-options],
[edit interfaces interface-name gigether-options]

Description

Enable or disable loopback mode.

Usage Guidelines

See Configure Loopback Mode.

Required Privilege Level

interface—To view this statement in the configuration.
interface-control—To add this statement to the configuration.

loopback (E1/E3, SONET, and T1/T3)

Syntax

loopback (local | payload | remote);

Hierarchy Level

[edit interfaces interface-name ds0-options],
[edit interfaces interface-name e1-options],
[edit interfaces interface-name e3-options],
[edit interfaces interface-name sonet-options],
[edit interfaces interface-name t1-options],
[edit interfaces interface-name t3-options]

Description

Configure a loopback connection. To turn off the loopback capability, remove the loopback statement from the configuration.

For DS-3 channels on a Channelized OC-12 interface, the sonet-options loopback statement is supported only for channel 0. It is ignored if you include it in the configuration for channels 1 through 11. The SONET loopback configured for channel 0 applies to all 12 channels equally. To configure loopbacks on the DS-3 channels, you must include the t3-options loopback statement in the configuration for each channel. Each DS-3 channel can be put in loopback mode independently.

Options

local—Loop packets, including both data and timing information, back on the local router's PIC. NxDS-0 QPP interfaces do not support local loopback.

payload—For Channelized T3, T1, and NxDS-0 QPP interfaces only, loop back data only (without clocking information) on the remote router's PIC. With payload loopback, overhead is recalculated. For T3 QPP interfaces, you can include the loopback payload statement at the [edit interfaces ct3-fpc/pic/port] and [edit interfaces t3-fpc/pic/port:channel] hierarchy levels. For T1 interfaces, you can include the loopback payload statement in the configuration at the [edit interfaces t1-fpc/pic/port:channel] hierarchy level; it is ignored if included at the [edit interfaces ct1-fpc/pic/port] hierarchy level. For NxDS-0 interfaces, payload and remote loopback are the same. If you configure one, the other is ignored. NxDS-0 QPP interfaces do not support local loopback.

remote—Loop packets, including both data and timing information, back on the remote router's interface card.

Usage Guidelines

See Configure E3 and T3 Parameters on ATM 1 Interfaces, Configure E1 Loopback Capability, Configure E3 Loopback Capability, Configure SONET Loopback Capability, Configure T1 Loopback Capability, and Configure T3 Loopback Capability.

Required Privilege Level

interface—To view this statement in the configuration.
interface-control—To add this statement to the configuration.

See Also

feac-loop-respond

loopback (EIA-530)

Syntax

loopback (dce-local | dce-remote | liu | local);

Hierarchy Level

[edit interfaces interface-name serial-options]

Description

Configure a loopback connection.

Default

If you do not include this statement, there is no loopback connection.

Options

dce-local—Loop packets back on the local DCE.

dce-remote—Loop packets back on the remote DCE.

liu—Loop packets back on the line interface unit (LIU).

local—Loop packets back on the local router's PIC.

Usage Guidelines

See Configure EIA-530 Loopback Capability.

Required Privilege Level

interface—To view this statement in the configuration.
interface-control—To add this statement to the configuration.