Supports I-4, S-4.1, L-4.1, L-4.2, and Ve-4.2 optical interfaces, of which the characteristics of I-4, S-4.1, L-4.1, and L-4.2 optical interfaces are in accordance with ITU-T G.957 recommendations, and the optical interface of Ve-4.2 is Huawei's customized standard.

Supports CWDM and DWDM color optical interfaces, and the optical interfaces use LC connectors.The CWDM optical interfaces support a transmission distance of 80km, and the DWDM optical interfaces support a transmission distance of 120km.

• Supports optical module information detection and query.
• The optical interface provides laser on and off setting and laser auto shutdown function.
• Supports the use and monitoring of SFP pluggable optical modules, which facilitates the maintenance and upgrading of optical modules.
• Support single-fiber bi-directional optical modules, single-fiber bi-directional optical modules do not support the use of pigtails for optical interface loopback.

• Supports segment overhead processing for STM-4 signals.
• Supports processing of channel overhead (transparent transmission and termination).
• Supports setting and querying of J0/J1/C2 bytes.
• Supports 1 channel ECC communication.

• Supports two-fiber multiplexing segment ring protection, four-fiber multiplexing segment ring protection, linear multiplexing segment protection, SNCP protection, SNCTP protection and SNCMP protection.
• Supports MSP and SNCP shared optical path protection. 1 SL4A board can support up to 1 MSP ring.

• Supports inner loopback and outer loopback functions at the optical port level.
• Supports VC-4 channel inner loopback and outer loopback functions.
• Support soft reset and hard reset, soft reset does not affect the service.
• Support the query function of veneer manufacturing information.
• Support FPGA online loading function.
• Support smooth upgrade of veneer software.
• Support one-button data acquisition.