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In this section, we are going
to learn about etherchannel.

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What is etherchannel? We will learn
about this using an example case.

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Let’s add 2 switch, we will use 2960.

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And then connecting this 2 switch using 2 cable.

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If we see here, one of the interface is orange,

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this is means that this interface
is blocked by spanning tree.

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Spanning tree is protocol that used
to prevent looping in the network.

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This protocol is active by default, so we
don’t need to worry about spanning tree.

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Here we can see that the interface blocked
by spanning tree is fa0/2 in the switch 0,

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let’s just remove the name of the interface so we
can see the topology clearly. Go to preference,

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and then uncheck always show port label.

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Okay now we can see the topology clearly. Here
we can see that the blocked port is in switch 0.

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Let’s add 1 more cable,

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here we can see that two cable or two
interface blocked by spanning tree.

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So remember that spanning tree will only
allow 1 cable active between switches,

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if there is 3 cable between switches like
this, spanning-tree will block 2 cable,

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and if there is 4 cable, so spanning-tree
will block 3 cable, and others.

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The case is, let’s say we need
high bandwidth between switches,

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let’s say the bandwidth of interface
is only 100 mega, but we need 300 mega.

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If we see here, we already connecting
this 2 switches using 3 cable,

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but 2 cable is blocked by spanning
tree, so here we just have 100 mega.

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but here actually we have 4 cable between
switches, let’s remove 1 cable. Okay so here we

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have 3 cable like this, and 2 cable is blocked by
spanning tree, so we only have 100 mega bandwidth.

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If we want 300 mega, we can use

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etherchannel. If we configure an etherchannel
in this 2 switch, all three cable will active,

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because etherchannel will combine this
3 physical cable become 1 logical cable.

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With etherchannel, switch will consider this
3 physical cable as only 1 logical cable,

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so spanning tree will not block any cable,
because there is only 1 logical cable.

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And there is no cable blocked by spanning tree,

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so now the bandwidth is 100
multiple by 3, which is 300 mega.

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Okay that is the concept of etherchannel,

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I think enough for this video, in
the next video, we are going to learn

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how to configure etherchannel.

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Thankyou for watching and see you on the next video.