Layer3 EtherChannel Configuration

                      Now in our last topic, we configured a “Layer2 Etherchannel”, and that might be very appropriate, If we had end to end Vlan’s in the Enterprise, another words, we got Vlan’s in Building 1, Vlan’s in Building 2 and Vlan’s in Building 3, and all the same. They are being shared between all those buildings, and we have Trunks interconnecting our buildings and case like that.

                   We might want to use “Layer2 Ether-channel’s”, however if we have a “Local Vlan’s” deployment, we might have Vlan’s within building 1, and the different set of Vlan’s within building 2, and different set of Vlan’s within building 3, and to get between buildings. Instead of sending traffic over a “Layer 2 Trunk”, we “Route between Buildings”. We need to leave a building not over a Trunk but over a “Routed Port”. We can do that with a Layer3 Etherchannel.

        “A Layer 3 Etherchannel is a connection made up of, a group of bundle ports, which we put into a logical interface, and those ports on that logical interface, they routed ports, instead of switchports”

Let’s take a look? How to set it up

Ø  SW2(config)#interface range fastethernet 0/1-2

Ø  SW2(config-if-range)#speed auto

Ø  SW2(config-if-range)#duplex auto

Ø  SW2(config-if-range)#mdix auto

ü  Reason we doing that is we wanna make sure that, we can use MDI-X, which were requires the “Speed and Duplex” to be set to “Auto”. MDI-X is gonna let me use Straight-Through Cables to interconnect these switches.

Now let’s convert these “Switchport” into the “Routed Port”

Ø  SW2(config-if-range)#no switchport

ü  Now fastethernet 0/1 and 0/2, they are now Routed Ports, we can could go in, and assign those “individual IP Addresses”. However instead, we want to bundle them together into the “Logical Etherchannel”.

Let’s use that Channel-group command again to create Virtual-Interface

Ø  SW2(config-if-range)#channel-group 1 mode on

ü  1:- locally significant number

ü  ON: - This way, we are not sending PAGP frames, we are not sending LACP frames, we just saying these this port to be a channel.

Let’s go into that Channel now.

Ø  SW2(config)#interface port-channel 1

Ø  SW2(config-if)#no switchport

ü  To make sure that, this Virtual interface is also viewed as a Routed interface, not a Switch interface

Now assign an IP Address, because this is a Routed Port.

Ø  SW2(config-if)#ip address 10.1.1.1 255.255.255.252

Once we set up, we want to confirm that we really are exchanging a Route information via OSPF, to do that, we want to create a loopback interface.

  Ø  SW2(config)#interface loopback 0
     Ø  SW2(config-if)#ip address 2.2.2.2 255.255.255.255

Now setup some Routing, let’s use OSPF. First we have to enable the IP Routing, which is disabled by default.

  Ø  SW2(config)#ip routing

  Ø  SW2(config)#router ospf 1

ü  1:- Process ID, locally significant

  Ø  SW2(config-router)#network 0.0.0.0 255.255.255.255 area 0

ü  Route for all networks, shortcut way

Done with Configuration on SW2.Let’s go over SW3 and give a similar Configuration

  Ø  SW3(config)#interface range fastethernet 0/1-2

  Ø  SW3(config-if-range)#speed auto

  Ø  SW3(config-if-range)#duplex auto

  Ø  SW3(config-if-range)#mdix auto

  Ø  SW3(config-if-range)#no switchport

  Ø  SW3(config-if-range)#channel-group 1 mode on

ü  Remember the other side is ON, it’s not gonna be sending or responding to PAGP or LACP frames, and as result the channel will be formed.

  Ø  SW3(config)#interface port-channel 1

  Ø  SW3(config-if)#no switchport

  Ø  SW3(config-if)#ip address 10.1.1.2 255.255.255.252

  Ø  SW3(config)#interface loopback 0

  Ø  SW3(config-if)#ip address 3.3.3.3 255.255.255.255

Routing Configuration:-

  Ø  SW3(config)#ip routing

  Ø  SW3(config)#router ospf 1

  Ø  SW3(config-router)#network 0.0.0.0 255.255.255.255 area 0

ü  Everybody belong to Area 0

 These switches now acting as Layer3 or Multilayer Switches. They are doing routing.

Verification & Troubleshooting: -

  Ø  SW3#show ip interface brief

ü  Make sure that, we have a newly created Virtual Interface

Now let’s make sure that, OSPF Neighborship formed over the Etherchannel

  Ø  SW3#show ip ospf neighbor

Now verify, have we learned any Network Information via OSFP over that Routed link

  Ø  SW#show ip route

Now go to SW2 and use same command

  Ø  SW2#show ip route

Conclusion: - That’s the look, creating a Layer3 Etherchannel for times, we want to have some extra bandwidth on a Routed Link interconnecting a couple of Multilayer Switches.

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