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Your CCNA studies are going to incorporate quite a bit of information about switches, and for great reason. if you don't comprehend standard switching theory, you cannot configure and troubleshoot Cisco switches, either on the CCNA exam or in the true globe. That goes double for trunking!  [http://www.dimango.com/lc-touch-controls.htm compare lamp touch dimmer]  Trunking is just enabling two or far more switches to communicate and send frames to every other for transmission to remote hosts. There are two main trunking protocols that we need to have to know the facts of for exam accomplishment and genuine-world accomplishment, but prior to we get to the protocols, let's discuss the cables we want. Connecting two Cisco switches requires a crossover cable. As you know, there are eight wires inside an ethernet cable. In a crossover cable, 4 of the cables &quot;cross more than&quot; from 1 pin to one more. For many newer Cisco switches, all you require to do to develop a trunk is connect the switches with a crossover cable. For instance, 2950 switches dynamically trunk when you connect them with the appropriate cable. If you use the incorrect cable, you are going to be there a whilst! There are two different trunking protocols in use on today's Cisco switches, ISL and IEEE 802.1Q, typically referred to as &quot;dot1q&quot;. There are three primary differences among the two. Very first, ISL is a Cisco-proprietary trunking protocol, where dot1q is the sector normal. (These of you new to Cisco testing ought to get utilized to the phrases &quot;Cisco-proprietary&quot; and &quot;industry regular&quot;.) If you are operating in a multivendor environment, ISL may possibly not be a excellent choice. And even though ISL is Cisco's own trunking protocol, some Cisco switches run only dot1q. ISL also encapsulates the entire frame, growing the network overhead. Dot1q only areas a header on the frame, and in some circumstances, doesn't even do that. There is much much less overhead with dot1q as compared to ISL. That leads to the third major difference, the way the protocols work with the native vlan. The native vlan is just the default vlan that switch ports are placed into if they are not expressly placed into an additional vlan. On Cisco switches, the native vlan is vlan 1. (This can be changed.) If dot1q is operating, frames that are going to be sent across the trunk line don't even have a header placed on them the remote switch will assume that any frame that has no header is destined for the native vlan. The dilemma with ISL is that is does not comprehend what a native vlan is. Every single frame will be encapsulated, regardless of the vlan it is destined for. Switching theory is a huge element of your CCNA reports, and it can appear overwhelming at very first. Just break your scientific studies down into smaller sized, far more manageable parts, and soon you will see the magic letters &quot;CCNA&quot; behind your name!