Ether channel across members of the same stack

[Jason Flory]

Hello Everyone

I am in the process of uplinking 2 fabric interconnects to a 3850 stack.  The FIs have 4 10 GB uplinks each and what I would like to do is uplink 2 uplinks on one stack member and 2 uplinks on another stack member and then create one channel group teaming all four links together.   From what i read this seems possible.  Anyone done this before?  Are their any downsides to this configuration.   Anything i need to do differently when doing cross stack ether channel.

Thanks

[jplenbrook]

Hi,

I am not too sure if I understand it correctly.

If you want to create an etherchannel using 4 ports on the same logical switch which will be going to another device which is not part of this stack, it is possible. I have not done it however I was planning to (failed because our router card doesn’t support l3 etherchannel dot1q trunk).

I can't see any downsides. This will allow you to create an uplink to another device capable of transferring 40 gbps which is an advantage.

Hope it helps.

[Jason Flory]

To clarify

FIs are fabric interconnects.  

Each fabric interconnect needs to be uplinked to the LAN.  Most docs talk about doing this on 2 Nexus switches that are not stacked.

Each FI has 4 x 10 GB uplinks and I want to create channel group for group of 4 uplinks but instead of all four going to one switch I would uplink two of the uplinks to switch1 and 2 uplinks to switch2.  Both these switches are in the same stack so theoretically they are one logical switch.  I have had issues doing this before but that was with non-cisco devices.

Reza mentioned FEXs which I understand to be fabric extenders.  Not really clear on what they do or if I even have them.  I do know that they are not the same is the FIs which are the fabric interconnects. 

Thanks 

[Reza Sharifi · Accepted solution]

Jason,

The reason I mentioned FEX is because FEXs have to get uplinked to a parent switch (Nexus 5500, 6000, 7000, etc..) Since you are not connecting the 3850 to FEX, than you don't have to worry about it.  As for your Portchannel, it should work fine, but it is more common to connect them to a set of Nexus switches running VPC.

HTH

[Jason Flory]

Next year we will be using getting a pair of 9k nexus switches.  Thanks for the advise.  Also for the clarification on FEX.  I keep seeing build docs for Hyper v and VM-FEX which uses the Fabric extenders.  From what I get FEX allows you to directly map virtual nics to a virtual nic on the fabric.

[Reza Sharifi · Accepted solution]

Hi,

Should not have any issue doing this.  I am not sure what FIs are, but hopefully you are not uplinking FEXes to the 3850 stack.

HTH