Can two switches with fiber ports be directly connected through fiber ports? The answer is yes. The mainline of the fiber optic LAN directly connects to the switch, then to the router.

The connection between two or more Ethernet switches in a certain way (Uplink port, etc.) is called the cascade. Theoretically, the cascade can go on endlessly, but in practice, it is recommended to cascade no more than four layers. Multiple switches can be cascaded in various ways according to needs. In a larger LAN such as the campus network, multiple switches generally form a cascade structure of bus type, tree type, or star type according to performance and usage.

However, you should note the following points when cascading switches of different manufacturers.

1. Whether the optical modules of the two switches are single-fiber or dual-fiber.

2. Whether the optical modules of the two switches are single-mode or multi-mode.

3. Whether the wavelengths of the optical modules of the two switches are the same. (For the single fiber module, you need to check whether the wavelengths of transceiver modules are the same).

4. Whether the optical power and optical sensitivity of the optical modules of the two switches are in the same range.

5. Whether the transmission distances of the optical modules of the two switches are the same.

6. Whether the port rates and duplex modes of the optical modules of the two switches are the same.

In general, the followings are the conditions of connection between two switches.

1. The same mode fiber unified single fiber or dual-fiber. If the modules are single and dual-fiber, you need to add a single dual-fiber converter between them.

2. Fiber mode unified single-mode or multi-mode. If the modules are single-mode and multi-mode, you need to add a single-mode to multi-mode converter between them.

3. The wavelengths of modules should be the same. (Dual-fiber: 850nm, 1310nm, 1550nm. Single-fiber: Send 1310nm, receive 1550nm, or other transmission and reception wavelengths).

4. Transmit optical power and optical reception sensitivity need to be in the same range.

5. Optical module transmission distances should be the same. But if meeting the above five conditions, you can connect the two optical modules within the distance of the shorter-distance module. And you need to check if the optical reception sensitivity of the long-distance optical module would be greater than the minimum overload point when reaching the opposite end.

6. Optical module rate and duplex mode should be set to mandatory 100 megabits, gigabit full-duplex, or self-negotiation. If they are set differently, the modules can’t be linked up. And 100 megabit optical port and gigabit optical port also can not be linked up.