> For the complete documentation index, see [llms.txt](https://prosbcdocs.telcobridges.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://prosbcdocs.telcobridges.com/tmedia-documentation/other-pages/hardware-and-lines/creating-an-oc3-line-interface.md).

# Creating an OC3 Line Interface

> **Applies to:** Tmedia 3.0, 3.2, 3.3

Line interface is a generic term for TDM physical interfaces. TelcoBridges products support 3 types of physical interfaces:

* [T1/E1/J1 interfaces](https://prosbcdocs.telcobridges.com/telecom-references/transmission-and-lines/t1-e1-and-j1-interfaces)
* [DS3 interfaces](https://prosbcdocs.telcobridges.com/telecom-references/transmission-and-lines/ds3-interfaces)
* [SONET/SDH interfaces](https://prosbcdocs.telcobridges.com/telecom-references/transmission-and-lines/sonet-sdh-interfaces)

To create an OC3 line interface(s):

1- Select **TDM Line Interfaces** from the navigation panel.

![CreateLineService 0](https://docs.telcobridges.com/w/images/d/dc/CreateLineService_0.png)\
2- To create a single OC3 line interface, click **Create New Line Interface**.

![CreateLineInterface 1 A](https://docs.telcobridges.com/w/images/0/0e/CreateLineInterface_1_A.png)\
This configures the **MAIN** interface on the rear of the TMG unit.

3- Enter values for the line interface.

* Enter a **name** for the interface
* Set **type** OC3 for the interface
* Set **local index** 0 for the line (this is the only choice for OC3)
* Select **Payload Type** STS3 (this is the only choice for OC3)
* Select **Use APS Protection** to use the redundant optical interface, named **APS** on the rear of the device.
* Click **Create**

  <br>

![OC3 Line interface Main](https://docs.telcobridges.com/w/images/1/10/OC3_Line_interface_Main.png)<br>

4- Verify that the **"Line interface was successfully created"** message is displayed

![CreateLineInterface 3 A](https://docs.telcobridges.com/w/images/4/4a/CreateLineInterface_3_A.png)

**Path**

```
/configurations/@[configuration_name]/hardware_units/@[hardware_name]/tdm_line_interfaces/@[line_interface_name]
```

**Parameters (text)**

```
/configurations/@[configuration_name]/hardware_units/@[hardware_name]/tdm_line_interfaces/@[line_interface_name]
local_index   = 0
name          = "@[line_interface_name]"
type          = "T1"

/configurations/@[configuration_name]/hardware_units/@[hardware_name]/tdm_line_interfaces/@[line_interface_name]/state
loopback_type = "None"
tx_state      = "TX on"

/configurations/@[configuration_name]/hardware_units/@[hardware_name]/tdm_line_interfaces/@[line_interface_name]/t1_parameters
encoding     = "B8ZS"
length       = "Short"
signal_level = "2"
```

**Parameters (json)**

```
{
  "local_index" : 0,
  "name" : "LI_T1_00",
  "state" : {
    "loopback_type" : "None",
    "tx_state" : "TX on"
  },
  "t1_parameters" : {
    "encoding" : "B8ZS",
    "length" : "Short",
    "signal_level" : "2"
  },
  "type" : "T1",
  "line_services" : {
  }
}
```

### List of Parameters

* [Name](https://prosbcdocs.telcobridges.com/telecom-references/parameter-reference/m3ua#n)
* [Type](https://prosbcdocs.telcobridges.com/telecom-references/parameter-reference/tdm#t)
* [Local Index](https://prosbcdocs.telcobridges.com/telecom-references/parameter-reference/tdm#l)

### Other links

[Automatic Protection Switching](https://prosbcdocs.telcobridges.com/telecom-references/transmission-and-lines/automatic-protection-switching)


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