Eherchannel

[himanshu.dheer]

Hi,

Thanks in advance !! 

Can someone please tell me why is their a master port chosen in an ether channel bundle ? Tried to search it online but no luck..

Himanshu

[InayathUlla Sharieff]

What do u mean by master port??

http://packetpushers.net/understand-etherchannel-load-balancing-catalyst-switches/

Above are some theory about other channel.

Hth

[himanshu.dheer]

Thanks for the link InayathUlla.. very informative !!

However, I was asking something else. Let me brief it

There is one master port selected in an etherchannel bundle. I don't know for what purpose and that is I wanted to know. You can check which interface is selected to act as master in output of # sh port-channel/etherchannel detail. Attaching the output for the same.

Hope this clears my question.

Himanshu

[Masoud Pourshabanian]

In ether channel you config a port channel, and then assign two or more interfaces to that port channel

Your interface port channel is "mstr".

All the ports member of port channel must have the same characteristic. If they have, you will

See :"up mstr in Bunle" .

Interface port channel1
switchport access vlan 2
switchport mode access
no ip address
!
interface FastEthernet0/1
switchport access vlan 2
switchport mode access
no ip address
channel-group 1 mode on
!
interface FastEthernet0/2
switchport access vlan 2
switchport mode access
no ip address
channel-group 1 mode on

[InayathUlla Sharieff]

Thats expected to see.

When ever the port-channel is configured thats the way you will see it on the output.If the port-channel config between the ports are look good then the po status will be what you are seeing.

In case one port is up and second port is not matching the parameter then the status will be something like this:-

SwitchA#show etherchannel 1 detail
Port state    = Up Sngl-port-Bndl Mstr Not-in-Bndl  >>>> one port is up but the other port is down.

Please have a look at the below link which gives you good info on what I am talking about:-

https://networklessons.com/switching/troubleshooting-etherchannel/

HTH

Regards

Inayath

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[Masoud Pourshabanian]

Cisco does not consider a master port in an ether channel; however, you can assign priority to each port. This priority determines which port become part of ether channel if device has limitation and not able to bundle all ports. As an example, you assign 24 interfaces to a ether channel and your device has hardware limitation and only able to bundle 8 interfaces so it uses priory to decide which ports should be bundled. Other16 ports will become Hot-standby and will be active if one or more of those 8 ports get disconnected.

Command: LACP port priority 1-32768.        Lower value is more likely to become active

To emphasize: There is no master port between active ports and Cisco use different method to load balance across active ports such as :

Destination IP, Destination MAC, Source Destination MAC and so on.

Hot-standby ports do not carry any traffic.

port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac}