If you try to drag a copper cable from a 2960 switch to an SFP port on a 3560 switch, Packet Tracer will refuse the connection. You need a translator.
Ensure both ends of the fiber cable are plugged into Fiber/SFP modules. You cannot plug a fiber cable into an RJ45 port. media converter in cisco packet tracer link
Understanding why Packet Tracer lacks this device teaches an important lesson: real-world physical networking often requires conversion hardware, but for logical design and protocol testing, the simulation can safely ignore it. When you move to real hardware or tools like GNS3/EVE-NG, you will need to account for actual media converters—but for CCNA-level design in Packet Tracer, the switch workaround is perfectly valid. If you try to drag a copper cable
Use a media converter when you do not need switching logic (MAC tables, VLANs). Use an SFP switch when you need management or multiple fiber links. You cannot plug a fiber cable into an RJ45 port
Let’s build a functional lab from scratch. Open Cisco Packet Tracer (Version 8.x or higher).