There are many medias to be used for interconnects among network equipment, copper and fiber, copper with its limitation of transmit distance, normally used for intra racks, and optics with longer transmission distance and used for inter-racks or inter-DCs.
As for the copper media, there is DACs and ACCs.
DACs, it is short for Direct Attach Copper Cable. DAC consists of a copper wire with modules on both ends. Due to limitation of copper wire, normally DAC cable with limited lengths up to 3 meter for 400G, 800G links now. but DAC cables popular used for intra rack connection for its feature of low cost, almost no power consumption and latency delay.
ACCs, Active Copper Cables are DAC copper cables but include a signal booster IC in the end to extend the length to 3, 4, and 5-meters depending on the speed. Compared with AOCs, ACC featured with lower cost, very low power consumption, and low latency delay.
As for the fiber media, there is ACOs, and transceivers
Active Optical Cables (AOCs) consist of an optical cable with multimode optical transceivers installed on both ends. It is a compete cable with fixed fiber lengths, cannot separate as modules and fibers. The AOCs normally offered up to 50 meters and are typically used in configurations with easy cabling access.
AOCs not recommended for OSFP form factor, since the module is very heavy may cause AOCs damage during installation.
Transceivers are used with fiber is flexible compared with AOCs, there is transceivers for multimode fiber and single mode fiber, Multimode transceivers with transmission distance up to 100m, and single mode transceiver with transmission distance up to 40km, or even longer.
Multimode transceivers
| Name | Description | Reach | Optical Connector | Speeds | Modulation |
| SR4 | Short Reach 4-channel | 50-100m | MPO-12/UPC | 100, 200Gb/s | 25G-NRZ, 50G-PAM4 |
| SR8 | Short Reach 8-channel | 100m | MPO-16/APC | 400Gb/s | 50G-PAM4 |
| 2xSR4 | Short Reach 2x 8-channel | 50m | 2x MPO-12/APC | 2x 400Gb/s | 100G-PAM4 |
Single mode transceivers
| Name | Description | Reach | Optical Connector | Speeds | Modulation |
| DR1 | Data center Reach, 1-channel | 500m | LC | 100Gb/s | 25G-NRZ, 100G-PAM4 |
| DR4 | Data center Reach, 4-channel | 500m | MPO-12/APC | 200G, 400Gb/s | 50G-PAM4, 100G-PAM4 |
| 2xDR4 | Data center Reach, 2x 4-channel | 500m | 2x MPO-12/APC | 800Gb/s | 100G-PAM4 |
| FR4 | Far Reach, 4-channel | 2km | LC | 200G, 400Gb/s | 50G-PAM4 |
| 2xFR4 | Far Reach, 2x 4-channel | 2km | 2x LC | 800Gb/s | 100G-PAM4 |
| LR4 | Long Reach 4-channel | 10km | LC | 200, 400Gb/s | 50G-PAM4 |
| ER | Extended Reach (WDM4) | 40km | LC | 100Gb/s | 25G-NRZ |
As a result, the naming of an optical transceiver consists of many descriptors such as:
“400G DR8 single-mode 500m, 8-channel electrical, 4-channel multiplexed optical, MPO-12/APC optical connector”
