Etherchannel vs Stack

[mynetwork014]

Dear all,

I want to know about the exact difference between Etherchannel and Stacking with some configuration

Which is recommended on which situation ?

[Leo Laohoo · Accepted solution]

Etherchannel and Stacking are two different things.  It's like apples and oranges.  

Etherchannel is "bundling" up to eight physical links (of the same speed) together to form one big, fat logical link.  

Stacking is "bundling" up to eight/nine SWITCHES together to form one logical switching unit.  

With a stack of switch, you can make Etherchannels.

[mynetwork014]

Dear Leo Laohoo,

Thanks for your quick response on this, i understood the concept but still i have some doubt if i want to provide redundancy for servers using switch then which one is better option between stacking and etherchannel.

[Reza Sharifi]

Hi,

It depend on the type of switches you are using. For example, if you are using 3750 series switches, you can stack multiple switches together to have switch redundancy and also have multiple uplinks from the stack to the servers using Etherchannel to get link redundancy.

So, lets say you have 2 switches stacked, you can then have a connection from each switch to your servers (if your servers have multiple NICs) using Etherchannel. Now you have switch and NIC redundancy.

HTH

[Reza Sharifi]

BTW, if you are using other platforms like the 6500 or Nexus, there is VSS and VPC to help you with redundancy.

HTH

[Leo Laohoo]

i understood the concept but still i have some doubt if i want to provide redundancy for servers using switch then which one is better option between stacking and etherchannel.

Maybe you "understand the concept".  But I believe you'll get a better grasp of the scenario if you actually get the chance to stack two (or more) 3750, 3650 or 3850 together and then configure etherchannel.  Do not configure the etherchannel in one switch.  Instead, configure the etherchannel in multiple switches that are part of the same stack.  Do this and you will get a clear picture and not just a "concept".  Stacking and Etherchannel has been on-going since the introduction of the 3750 family of switches.  You will appreciate the technology more by configuring Etherchannel with Stacking instead of just plainly reading it.

NOTE:  You really want to avoid using Catalyst switches for access to servers.  This is because Catalyst switches were intentionally built with very shallow memory buffers.  The shallow memory buffers are no match to the intensity of continuous flow of data to and from servers.  

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Normally you would want both.

I.e. Etherchannel with links to different stacked switch ports.

PS:

As Leo notes, unfortunately, many (all?) of Cisco's stackable have rather shallow buffers.  However, this doesn't guarantee that they are totally unacceptable to be used with servers, but they can be.  It really depends on your expected traffic patterns.  (It also depends what ports you use.  On the 3750X, uplink ports have more buffer memory to share than the copper edge ports.  Also the later stackable switches often support 10g ports too.)