How to add an alternate stacking switch to a stack that is using native stacking?

I currently have a stack of 3 x450-g2-48-10g4 switches that are stacked using the qsfp+ ports on the back of the switches in a ring. I would like to add an x440-g2-48-10g4 to that stack. The 440 only has the sfp+ ports for stacking. (Alternate/Summitstack-V). The 450 also has available sfp+ ports that it can use for alternate stacking. 

The EXOS User Guide says that a single stack can contain both Native and Alternate stacking switches. If so, is there a config guide I could use for this? The first time I tried to add the 440 to the stack I call TAC and they said it couldn’t be done.

Thanks for any info!

2 replies

Userlevel 6

In my opinion this should work and the stacking tool also confirms this:


I have never done this, but I would do it like this:

  • Disconnect the stacking cable between the first and last X450-G2, so that it is no more a ring, but daisy-chain. Stack Port 1 of the first X450-G2 and Stack Port 2 of the last X450-G2 should now be down.
  • configure the following on the first X450-G2:
    • configure stacking-support stack-port 1 selection alternate
  • confgure the following on the last X450-G2:
    • configure stacking-support stack-port 2 selection alternate
  • On the X440-G2 execute the following
    • enable stacking-support
  • Make sure that X440-G2 has the same firmware installed (in the same partitions) and that the stacking-protocol matches the X450-G2 stack by using
    • show stacking configuration
    • show stacking details
  • put the X440-G2 in the rack (don’t power it up yet) and connect it to the stack:
    • connect X440-G2 Port 49 to the last X450-G2 Port 52
    • connect X440-G2 Port 50 to the first X450-G2 Port 51
  • power up the X440-G2
  • wait a few minutes and check on the stack if the new switch is recognized using the command “show stacking”. If it is seen:
    • configure stacking node-address <MAC_OF_NEW_SWITCH> slot <SLOT_#>
    • synchronize stacking node-address <MAC_OF_NEW_SWITCH>
    • enable stacking node-address <MAC_OF_NEW_SWITCH>
    • reboot node-address <MAC_OF_NEW_SWITCH>

Since I have never done this, I can’t guarantee anything. If it is an productive and critical stack, maybe wait for someone to confirm (or deny)... :D

some links:

How To: How to Create a Stack with Summit Switches | Extreme Portal (

How To: How to Add a Node to a SummitStack | Extreme Portal (

ExtremeSwitching Hardware Installation Guide (

Best regards

Thank you for the detailed reply Stefan. I had also used the stacking tool like you did, which made me think this is possible. I am going onsite today to try this config. I will update the thread afterwards.