CoronadoFitz873

Your CCNA studies are going to incorporate fairly a bit of information about switches, and for very good reason. if you don't understand basic switching theory, you can't configure and troubleshoot Cisco switches, either on the CCNA exam or in the actual globe. That goes double for trunking!

Trunking is basically enabling two or much more switches to communicate and send frames to every single other for transmission to remote hosts. There are two main trunking protocols that we need to know the facts of for exam success and actual-globe achievement, but just before we get to the protocols, let's go over the cables we need.

Connecting two Cisco switches demands a crossover cable. As you know, there are eight wires inside an ethernet cable. In a crossover cable, 4 of the cables "cross more than" from a single pin to another. For numerous newer Cisco switches, all you need to have to do to generate a trunk is connect the switches with a crossover cable. For instance, 2950 switches dynamically trunk as soon as you connect them with the right cable. If you use the wrong cable, you are going to be there a even though!

There are two distinct trunking protocols in use on today's Cisco switches, ISL and IEEE 802.1Q, typically referred to as "dot1q". There are three primary differences between the two. Initial, ISL is a Cisco-proprietary trunking protocol, where dot1q is the sector regular. (Those of you new to Cisco testing must get employed to the phrases "Cisco-proprietary" and "market standard".) If you happen to be operating in a multivendor environment, ISL could not be a great option. And even even though ISL is Cisco's personal trunking protocol, some Cisco switches run only dot1q.

ISL also encapsulates the entire frame, growing the network overhead. Dot1q only locations a header on the frame, and in some circumstances, doesn't even do that. There is considerably much less overhead with dot1q as compared to ISL. That leads to the third main distinction, the way the protocols function with the native vlan.

The native vlan is basically the default vlan that switch ports are placed into if they are not expressly placed into one more vlan. On Cisco switches, the native vlan is vlan 1. (This can be changed.) If dot1q is running, frames that are going to be sent across the trunk line do not 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 issue with ISL is that is doesn't comprehend what a native vlan is. Each and every single frame will be encapsulated, regardless of the vlan it really is destined for.

Switching theory is a large element of your CCNA research, and it can seem overwhelming at first. Just break your scientific studies down into smaller, more manageable parts, and soon you'll see the magic letters "CCNA" behind your name! door buzzer