A rollover cable with a RJ-45 connector will plug into a console port on a Cisco device, the other end can be a DB-9 connector or another RJ-45 that can plug into an adapter.
Typically a 9 pin serial Null Modem cable, although some devices specify a straight though standard 9 pin serial.
Your looking for an ethernet cable
a rollover cable
RJ 45....
If you connect to the router via the console port then you are physically making a connection with a physical cable to the router. This implies you have to be close to the router itself. Using telnet allows you to connect to the router from anywhere in the network, and doesn't require a physical cable connection.
Console cable. DB4
make a connection from the router's console port to your laptop's serial port and configure the router from your laptop.
crossover cable
Rollover
A rollover cable is typically used to connect from a DB9 serial port on your computer to the RJ45 console port on the router. An RJ45-RJ45 rollover can be used from Aux port to Console port or from the ports on a 2509-RJ/2511-RJ to a console port.
Rollover cable (also known as Cisco console cableor a Yost cable) is a type of null-modem cable that is often used to connect a computer terminal to a router's console port
A rollover cable is used in a networking environment where a router/switch is to be configured from a computer. One end is wired one way but on the other it is reversed. You would typically use one end into a serial port on a PC and the other into the console port of the switch/router. It is common within cisco configurations. Hope I helped
Should you start a Cisco router sans config (as is the case when you first purchase it), then it will not do anything but power on - yet. You must attach a cable to the console port of the router on one end, and the serial port of your computer at the other. This can also be done using a rollover cable to connect the router's console port to your computer's ethernet port. Once connected, you can use HyperTerminal, Cutecom, or another serial communication terminal program to see the console input.output from the router. It will ask you if you would like to enter the initial configuration script. Type yes and work from there!
console port
To connect to a terminal for initial configuration
Console port is used