Hi Masood,

RJ 21 connectors are basically having 50 pins in a single connector, thus usually these connectors are used to connect Ethernet ports in bulk from a switch with RJ-21 ports to a CAT-5 or CAT-6 rated patch panel, or between two patch panels.i.e. each connector can support upto 12 ethernet ports thus you can save a lot of cabling, space and may be cost too.

If you decide to change them to RJ-45 or fiber ports, you need to change the cabling, cards on routers and switches and probably more space and cost would be involved in doing so.

* Pls rate if helps.

Manmeet

In case