What are the differences between OSC and ESC in OSN8800 Network?

OSC (Optical Supervisory Channel)

The OSC board provides private optical supervisory channels for the WDM equipment to transmit the supervisory information of the NEs.

Functions and Features

The main features of the OSC are as follows:

• Occupies private wavelength to transmit the supervisory, OAM information.
• Ensures that the ultra-long transmission can be achieved without the signal amplification.
• Uses the CMI line encoding. The sensitivity of the receive side is greater than -48 dBm.

Signal flow of the OSC between three stations in chain networking

Electric Supervisory Channels (ESCs)

The ESC transfers the NE supervisory information by using the overhead bytes (DCCs/GCCs) in the fixed frame structure of the service. In this case, the communication between NEs can be achieved directly through the interconnection of the OTU units, tributary units or line units.

Huawei transmission devices can use ESCs to transmit supervisory and management information and achieve communication between each other. An ESC uses GCC0, GCC1, or GCC2 bytes that are compliant with ITU-T G.709 and contained in frame headers of OTU and tributary boards. It can also use pilot tune DCC bytes of LWX series boards.

Functions and Features

The main features of the ESC are as follows:

• Transfers the supervisory information through the interconnection of the OTU units, tributary units or line units so that dedicated supervisory unit is not required.
• Transfers the supervisory information along with the primary service signals.
• Transfers the supervisory information without occupying wavelength resource.

ESC signal flow in the chain networking

Comparison Between OSC and ESC

The OSC and ESC have their own features and advantages. The OSC and ESC have fixed proprieties and systems can automatically determine whether to use the OSC or ESC based on their proprieties. Users can manually shut down the OSC and ESC using the NMS.

Item	OSC	ESC
Applicable board	HSC1/SC1/SC2/ST2/DAS1/AST2	OTU, tributary board, line board
Transmission channel	D1-D3, D4-D12, OSC_18, FE_DCN, FE_DCN_ASON	GCC0, GCC0_18, GCC12_9, GCC12_18, GCC1_24, GCCM_24, RES_ODU, pilot tune DCC
Maximum distance	Smaller than 200 km. The value depends on board types.	No limit. The value depends on service type.
Stability	High	Medium
Cost	Because the optical supervisory channel board is used, the cost is relatively high.	Low
Maintainability	High	Low
Stability of ECC topology	Fixed and stable	Low. The stability varies according to services.
Restriction	All NEs, except for the extended ECC subrack, require the optical supervisory channel board	The OLA stations cannot be managed.
Note: The GCC0_18 and GCC1_24 channels are supported only by TN15LSXL, TN55NS3, TN54NS4, TN57NS4, TN58NS4, TN96NS4, TN11LTX, TN12LTX, TN15LTX, TN12LSC, TN13LSC, TN56NS4, TN56NS3, TN54HUNS3, TN15LSC, TN17LSC, TN17LTX, TN97NS4, LSCM, TN18LSC, TN54NP200, TN54NP200E, TN11LDC, TN11LQCP boards. The D4-D12, GCC1_24, RES_ODU, and GCCM_24 channel bytes are used to transmit ASON information by default. Users can configure them to transmit ASON or DCN information on the NMS.

The ESC-based ECC network topology depends on the allocation of wavelengths, which is more flexible than the OSC. The disadvantage of the ESC-based ECC network topology is that it is inconvenient for management and maintenance.