What are the types of supervisory channels in the Optical Transmission world?
There are two types they are:
OSC
ESC
The first is called OSC, which means optical supervisory channel, and it is a control signal that is sent with the main data signals, but on a different wavelength, which is 1510 nanometers, for example.
It is sent with enough power to reach because it is not amplified and does not pass through the amplifier
The amplifier does not support its frequency
One of its features is to control the site remotely, follow it, and know its status, even if there is a problem with the cards inside the site, especially the amplifier, Mux, Transponders card.
It is determined through the control card and is sent through a card called OSC processing board, and an example of this card is in the Huawei cabin.
ST1
SC1
While the ESC is called the electrical supervisor channel and it is sent from the control card through the transponder and placed inside the data frame, so we will not need an osc board and will not need any osc wavelength
One of the advantages of using ESC is that it is simple to use and also low cost
Its main drawback is that it cannot be used in the OLA site
OLA : optical line amplifier
Also, you will not be able to use order wire if you use ESC
Notes:
The 1310 nm wavelength can be used by the OSC port of an SCC board on OSN 1800.
If both OSC and ESC are available between two NEs, the priority of DCC channels in use are as follows:
GCC12_1; GCC12_9; D4-D12; D1-D3; pilot-tone DCC2.
If the available DCC channels have the same bandwidth, follow the sequential orders that DCC channels were identified by the NE instead of the DCC channel ID in ascending order.
Generally, this is related to the order of the boards going online, namely, the NE preferentially choose the DCC channel of the board that goes online first to deliver monitoring messages.
Some OTU boards such as L4G can also use D1 to D3 channels by modifying the service type to SDH at the WDM side.
The priority of ESC monitoring channels of NG WDM is higher than OSC.
When both the OSC and ESC are enabled for a system, the system uses and switches channels for DCN communication according to the following priorities: FE_DCN(Including the FE_DCN_ASON channel) > GCC0_18 > GCC12_18 > OSC_18 > GCC12_9 > D1_D3 > GCC0 > pilot tune DCC.
More: Compare between the OSC and ESC
Thank You.
