What is the diff between interface vlan and portchannel

[mirror512]

ho guys ,

I am studying for switching and i am totally confused between these things. I want to what is the difference between them and

int fa0/1
no switchport
ip add 10.10.10.1 255.255.255.0

interface vlan 1
no switchport
ip add 10.10.10.1 255.255.255.0

interface port-channel 1
no switchport
ip add 10.10.10.1 255.255.255.0

[ankugarg]

Port channel is etherchannel interface,which is used when some ports are bundled together.

vlan 1 is virtual interface which acts as default gateway for ports in that vlan.

fa0/1 is physical interface.

[mirror512]

I created

interface vlan 1

interface vlan 1
no switchport
ip add 10.10.10.1 255.255.255.0

then

  int range fa23/24
channel-protocol lacp
chanel-group 1 mode active

I want to know do i need to create port channel

because i did not create one but it gets automtically created

[ankugarg]

This port channel got created because you gave command  "chanel-group 1 mode active" under  interface config mode...This means that you are bundling ports 23 and 24..These two ports will behave as one port...In effect you are doubling the bandwidth of the link

[mirror512]

then what is the use of this command

interface port-channel 1
no switchport
ip add 10.10.10.1 255.255.255.0

[ankugarg]

Like any normal link can be L2 or L3,port channel link can also be L2 or L3..By giving above commands you are giving "no switchport" to port channel interface,and in turn making it L3 interfcae..If you don't give "no switchport",you won't be able to give ip address to this interface because it will be L2 interface.

[Somasundaram Jayaraman · Accepted solution]

Hi,

Port-channel is used to bundle the links so that you will have more bandwidth for traffic to pass.

If you have two 10 gig links, if you bundle the two links you will get 20 gig of bandwidth.

Port-channel is usually configured in trunk links, since all the vlans are passing through the trunk.

Also we have failover mechanism in port-channel, say if one of the interfaces fails then the traffic will pass through the other link

This not true in normal trunk links, since if the link fails, then the traffic going across the trunk link will get dropped.

For the first question:

===============

++ You have configured the interface fa0/1 as layer 3 port.

++ Interface vlan is always layer 3. So no need of giving no switchport over there.

++ The port-channel is a layer 3 portchannel, thereby you are restricting the spanning-tree convergence across the network. This is efficient since there wont be any spanning tree convergence in the port-channel since it is a layer 3.

For the second question:

==================

++ You have configured interface vlan 1 which will be the gateway for members in vlan 1

  int range fa23/24

channel-protocol lacp

chanel-group 1 mode active

++ you made fa 23/24 to be a part of port-channel 1.

There is no need for creating port-channel because whenever you configure an interface with channel-group command, the port-channel is automatically created.

Some useful commands:

==================

++ show etherchannel summary

++ show etherchannel summary

The below link might interest you.

-http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_13_ea1/configuration/guide/swethchl.html

Hope this helps

Cheers

Somu

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