Before connecting the IMG 1010 to a network, it must be synchronized to a T1/E1 loop timing source such as a T1 or E1 DS-1. The IMG 1010 will accept up to four separate clock sources connected to various interfaces on the rear of the unit. The IMG 1010 - Timing Synchronization Priority List object defines the priority the IMG 1010 uses when selecting a clock source to sync to. Once the timing sources are connected, the Timing Synchronization Priority List determines which source gets highest priority, 2nd highest priority, and so forth to lowest priority. To create the Timing Synchronization Priority List, right click on the IMG Name object and select New Timing Synchronization Priority List. Below is an explanation of each of the timing references. The Pinouts of the RJ48 connectors are shown in IMG 1010 - RJ 48 Connector Pinouts.
The IMG 1010 cannot time off an atomic clock or similar. The TDM inputs on the rear of the unit will only accept a loop timing clock source from a T1, E1, or DS3.
IMG 1010 Back Panel
Configuration
Network Timing can be configured on any span on the 2020 IMG. Below is a list of the different timing sources supported.
Timing Source Label | Description |
Primary Reference | Primary Reference is hard-coded to the DS-1 within Signaling/Timing interface 0. The timing source does not need to be configured. Connect a DS-1 to this interface and the IMG 1010 will automatically synchronize with the T1 or E1 loop timing source. |
Secondary Reference | Secondary Reference is hard-coded to the DS-1 within Signaling/Timing interface 1. The timing source does not need to be configured. Connect a DS-1 to this interface and the IMG 1010 will automatically synchronize with the T1 or E1 loop timing source. |
Primary Loop | Primary Loop timing can be configured on any DS-1 other than the DS-1's used for Primary and Secondary Reference timing described above. To configure, highlight one of the Bearer Interfaces in the Object Table at bottom of the Bearer Span object. Right click and select Set Primary. Once the timing source is set, the Primary Loop selection in the Timing Synchronization Priority List can be moved to a higher position as required. |
Secondary Loop | Secondary Loop timing can be configured on any DS-1 other than the DS-1's used for Primary and Secondary Reference timing described above. To configure on, highlight one of the Bearer Interfaces in the Object Table at bottom of the Bearer Span object. Right click and select Set Secondary. Once the timing source is set, the Secondary Loop selection in the Timing Synchronization Priority List can be moved to a higher position as required. |
Free Running | The Free Running source is the clock source generated internally. It is not recommended that the Free Running source be used as an external clock source used to time the network. The Free Running source is used as a backup source in the event all network timing sources have failed. The Free running timing source should always be configured as the last clock source in the Timing Synchronization Priority List. |