Original subtitles

So let's optimize the links between the two core switches.

Using ether channel once again shows spanning tree v land 10 shows us of that on call 1 all ports of

forwarding but if we have a look at a v land twenty notice port 24 is blocking something similar is

shown on call to show spanning tree v land one port twenty four is blocking for v land 10 port of 24

is blocking the big issue here is if traffic for example from VLAN 10 is sent to the Internet that traffic

is gonna traverse this link gigabit one zero twenty three because Port 24 is blocking if traffic is

central from VLAN twenty to the server that traffic is going to go to court to and then go across gigabit

one zero twenty three to the servers.

In other words you may have many devices at the access layer sending traffic to servers on the left

hand side or two devices on the right hand side such as the Internet or other servers any traffic that

goes via call 1 to CO 2 can only use port twenty three and any traffic that goes to court to and then

to call one to get to two the servers can also only use Port 223 port 24 even though it's plugged in

in this topology is not used at all for sending traffic from call 1 to CO 2 so for VLAN twenty core

one is blocking port 24 for VLAN 1 CO 2 is blocking port 24.

Same is true for VLAN 10 for vlan 100 called to his forwarding but for vlan 100 call 1 is blocking support

24 is not used even though it's plugged in so to resolve that we want to bond these two links together

in an ether channel now in this video I'm gonna show you some of the issues that you could encounter

with ether channels or link aggregation or port channels you'll see different names used for this technology

so as an example one of the things you need to remember is that when you add physical interfaces to

a port channel you need to do the configuration on the port channel rather than on the physical interfaces

the configuration that you do on the logical port channel should fall to down to the physical interfaces.

In other words the config that you apply on the logical port channel should be copied and applied on

the physical interfaces by the switch.

That doesn't always work or doesn't always happen.

So if you have problems with port channel you need to verify the configuration on the portrait Channel

and other physical interfaces and then you need to make sure that everything is the same on both sides

on both a logical port channel and the physical interfaces then shut it down.

The physical interfaces and then no shut them so I'm going to show you a bit of troubleshooting in this

video as I configure port channels and I'm going to show you some of the issues that you could encounter.

If you do configuration on the physical interfaces but not on the logical port channel.

So if you configure the physical interfaces are not the logical port channel.

You can have issues where the port channel is for example and access port rather than a trunk port even

though your physical interfaces are configured as trunk ports.

The moral of the story is make sure that the configuration of the port the channel and the physical

interfaces is the same.

Once you've shut down the physical interfaces if needed confirm that the configuration is the same and

then no shut.

The physical interfaces so to set up ether channel going to go into the interfaces and in this case

I'll use a range command and I'll specify both interfaces I'll shut both down.

It's a good idea to shut your interfaces down when making changes like this.

In our example we gonna use what's called a layer to ether channel so we going to run attitude of one

cute tagging across the links.

It's going to act as a traditional layer to interface rather than a rounded or layered 3 interface.

So switch port mode trunk means that it'll act like a trunk.

And now we can use the command channel

group and select a number.

I'm going to select a channel group one such as can support multiple either channels or multiple ether

channel groups.

The reason why is that you could use group one to bond to these two links together and if you had multiple

ports from your call switch to your access switch let's say from call one to access one you could bond

to both of those links together in ether channel to some multiple ether channels can be configured.

In this example I'm simply going to use ether Channel One I'm going to specify the mood.

And notice here we have five different modes.

Now before we talk about modes you need to understand that we have to link aggregation protocols ACP

or link aggregation control protocol and PDP or port aggregation protocol Al ACP is an industry standard

protocol PDP is a Cisco proprietary protocol so you can either use Al ACP or BGP or you can disable

the use of a protocol and just enable a link aggregation on a port.

So if you set the mode two on the switch is not going to negotiate with the switch on the other side

to set up an ether channel.

It's simply going to turn it on if you want to use LCP.

You can either use active or passive LCP now active means that to the switch will use alt ACP messages

to negotiate with the other side and actively try and form an ether channel with the switch on the other

side of the link.

So if I said active on switch one it's going to try and get switched to to form an ether channel on

these ports.

Passive means that the switch doesn't try and actively form an ether channel.

It waits for either channel messages and if it receives them then it will form an ether channel with

the device on the other side so active means it's actively trying to form an ether channel.

Passive means it's just passively waiting until the other side initiates the forming of an ether channel.

So you need to specify which protocol to use LCP or PDP and then with Ali ECP you have the option to

specify either active or passive BGP does something similar.

We have either desirable or auto desirable is like active in LCP the switch is going to actively or

desirable we form an ether channel auto in PDP is like passive in LCP it's only going to form an ether

channel if the other side initiates the forming of an ether channel.

So in this example I'm going to specify active to use ACP and to actively create a link aggregation.

Notice the switch tells us that a portal channel interface has been created a port channel interface

is an ether channel interface.

So if we type do show run what we see now is that this port channel has been created and if we scroll

down we can see that this interface gigabit 1 0 twenty three is part of the port channel or either channel

and so is gigabit.

1 0 24 now won't know shutter the interface yet.

I'll go to switch to and do something similar.

On switch to these interfaces have gone down because we shut them down on such one to do something similar

here.

Interface range gigabit 1 0 23 to 24.

I'll shut them down anyway.

Set the switch port mode to trunk channel Group 1 notice we have options 1 248 mode active.

We need to use the same protocols.

So either LCP or GP on both sides.

I could have set the side too passive so that switch 1 initiates the aether channel but in this example

I'm gonna get them both to actively try and form a link aggregation on those shuttered interfaces on

the side and I'll know shutter them on call 1 both physical interfaces have come up and so has the portrait

channel so show is a channel summary in the output here.

From the show ether channel summary command we can see that gigabit 1 0 23 and 1 0 24 are part of the

port.

Channel so both ports have been put into the port channel.

We can see that port.

Channel 1 or ether Channel 1 is used as means of that it's only a two if a channel not a layer 3 ether

channel.

In other words it's using switching rather than routing you means that the other channel is in use.

So that's great.

Both ports are part of the ether channel and the ether channel is in use.

Show ether channel summary on the side we see something very similar.

Show ether Channel port channel.

This gives us a lot of information so this command shows us that we have a group.

Group 1 port.

Channel number is 1.

The channel has been up for this length of time.

There are two ports in the ether channel.

We are using ACP as the protocol on the channel and these two ports gigabit 1 0 23 and 24 are active

in the channel.

This is the time since the last port was bundled so gigabit 124 was added to the third channel about

one minute and 38 seconds ago on the side.

We should see something very similar so show either a channel port channel.

Notice we can see that both ports are active in the channel.

That's good and that's what we want to see.