what problem will face if we will add 9 physical port in etherchannel

[kousikdutta]

Hi All,

I have a quarry that what will happen if we add 1 or 2 physical port in port-channel.

However cisco TAC is recommending to bind 4 physical port in port channel, Kindly help me get the clarity on this.

[shambhu.kumar · Accepted solution]

You can assign up to 16 physical interfaces to an EtherChannel, but only eight interfaces will be active at a time.

https://community.cisco.com/t5/switching/etherchannel-max-number-of-ports/td-p/3189881

[Joseph W. Doherty · Accepted solution]

Using a 9 port Eitherchannel, I recall (?), is not a feature of earlier implementations and in later implementations up to 16 ports can be configured but only 8 actively used, the latter as also noted by @shambhu.kumar .

BTW, when you have a bandwidth need for, perhaps, 4 or more ports, if possible, you may want to consider using fewer ports that offer more bandwidth.  (Also keep in mind, fewer higher bandwidth ports generally provide more effective bandwidth than Etherchannel's aggregate bandwidth.  Fewer such ports might even be less expensive especially when adding in cost of optical transceivers.)

[MHM Cisco World · Accepted solution]

It recommend not mandatory' you can use up to 16 it depend on you.

Also I have 24 port SW if I use 9 for PO there will be only 15 ports for host.

MHM

MHM

[Joseph W. Doherty · Accepted solution]

". . . you can use up to 16 it depend on you."

For clarification, you can configure up to 16 ports, but only 8 will be actively used.

Also BTW, 8 ports was a limitation of Cisco's earlier PAgP, while the later LACP allowed a total of 16 ports, but only 8 activity passing transit traffic.  (I recall [???} Cisco might not have supported LACP's 16 links when LACP was initially added as an alternative to PAgP.)