Cisco Certification A Survival Guide To The Cisco Cable Jungle

Cisco Certification A Survival Guide To The Cisco Cable Jungle

Cisco Certification: a​ Survival Guide To the​ Cisco Cable Jungle
One of​ the​ most confusing parts of​ beginning your Cisco studies is​ keeping all the​ cable types separate in​ your mind, and​ then remembering what they’re used for​ .​
This often occurs when a​ CCNA or​ CCNP candidate starts putting together their own home practice lab, and​ they suddenly realize that they have the​ equipment to​ run labs, but not the​ cables.

With this in​ mind, here are some common Cisco cable types and​ their primary use.

First, there’s the​ regular old straight-through cable, so named because the​ eight wires inside the​ cable go straight through the​ wire .​
While the​ wires may be twisted inside to​ reduce electromagnetic interference (EMI), the​ wire that’s connected to​ Pin 1 on one end is​ connected to​ Pin 1 on the​ other end, and​ so on .​
In a​ home lab, a​ straight-through cable is​ often used to​ connect a​ switch port to​ an​ Ethernet port on a​ router, with a​ transceiver attached to​ the​ Ethernet port .​
Straight-through cables are also good for​ connecting a​ BRI interface to​ an​ ISDN simulator.

The crossover cable is​ so named because the​ wires do cross over between pins .​
This allows the​ devices to​ both send and​ receive at​ the​ same time, and​ crossover cables are a​ must for​ directly connecting ports on Cisco switches to​ create a​ trunk.

The rollover cable allows you to​ connect directly to​ a​ Cisco console port with your laptop or​ PC .​
This is​ the​ blue cable that comes with new Cisco devices, and​ it’s the​ one that engineers tend to​ hold on to​ with their lives .​
Without a​ rollover cable (also commonly called a​ console cable), you can’t connect your laptop directly to​ a​ Cisco device.

Finally, there’s the​ DTE/DCE cable .​
To create a​ frame relay cloud in​ your home lab (using one of​ your Cisco routers as​ a​ DCE), or​ to​ directly connect two Cisco routers via their serial interfaces, you will need a​ DTE/DCE cable .​
Remember that the​ DCE interface will need to​ supply clockrate to​ the​ DTE interface.

The different cable types can be confusing when you first read about them, but after tearing down or​ building your home lab a​ few times, you’ll definitely have them straight come test day!

Best of​ luck in​ your lab and​ your exams,

Chris Bryant
CCIE #12933

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