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Noted that each stacking module has two ports with which it's used to connect to another switches docking

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module.

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So as an example if you've got four switches each switch has a stacking module and four cables are used

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to connect the force switches together the way you think of this is the switches are a stack of switches

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in the same rack.

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One of the reasons for doing that is that the stacking cables are very short in length so it's expected

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that the switches are physically positioned next to each other.

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On top of each other as an example some of the Cisco stacking cables are only half a metre in length

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or one metre in length or three metres in length.

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Again you need to think of a switch stack as a logical single switch.

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You may have four physical switches but logically they're acting as one switch.

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One of the switches in the stack becomes the stack master and it's used to control the rest of the switches

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in the stack.

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The physical stacking cables connect the physical switches to each other and allow for communication

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between the switches and the stack.

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But the monster switches in control of the stack.

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If as an example you have four switches in a stack and a frame arrives on switch for and each to exit

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out a switch.

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Three to switch one is the master switch switches one three and four all need to communicate over the

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stack links to forward the frame switches one three and four would need to communicate with each other

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over the stack links to forward the frame switch one being the monster switch would match the Ethan

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at frame to the MAC address table and would then decide out of which port to forward the frame.

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Think of the master switches the brain of the stack logically in a topology like this.

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We have two physical switches.

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But logically they are a single switch and the same would be true if we had four switches in a topology

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like this we may have four access switches connected via stacking cables.

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So physically it would look like this

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but logically it looks like this.

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The switches appear to be a single switch to the rest of the network and you configure them as if they

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are a single switch.

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We now have four uplinks to each distribution switch.

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So physically they're connected as follows.

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With each access switch having one connection to each distribution's switch but logically we have four

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physical cables to each distribution switch which then allows us to use either channel to the distribution

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switch.

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So rather than using spanning tree across these uplinks we're one of the porters forwarding and one

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of the ports is blocking.

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We've now created an ether channel to each distribution switch.

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This kind of setup simplifies the configuration and management of the network from a spinning tree point

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of view rather than having six switches involved in the spending tree.

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We now only have three switches involved in the spending tree.

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So it's much easier to configure.

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Much easier to understand as well as to predict what happens when there's a failure in the network uploading

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across an ether channel.

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He's also more efficient than using spanning tree to block one port and forward on another port.