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Stacking question, 2930M switches

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  • 1.  Stacking question, 2930M switches

    Posted Nov 06, 2019 09:02 AM

    We are running 2930M switches in most of our wiring closets. Some of these are in a three-switch stacking configuration. We have DACs connecting the switches as follows:

    Sw. 1 stackport 2 connects to Sw. 2 stackport 1

    Sw. 2 stackport 2 connects to Sw. 3 stackport 1

    Sw. 3 stackport 2 connects to Sw. 1 stackport 1

    What we're seeing is that, on some switch stacks, the connection from Sw. 3 to Sw. 1 shows the LEDs flashing green and the CLI command 'show stacking stack-ports' indicates that these two ports are down. So instead of a ring topology, it's a chain topology. Also, the 'show logging' command output lists these two ports (stackport 1, Sw.1 and stackport 2, Sw. 3) constantly being inserted and removed. 

    We're not seeing this on all our stacks - some are fine with solid green LED status on the stack ports, 'up' status in the 'show stacking stack-ports' command output and not flapping indicated in the log output.

    Any idea what might be causing such a condition? First thought is a cable not seated securely, but I'm reluctant to just pull it and re-connect it during working hours - not sure of the effect that would have on connectivity for users, etc.

     

     



  • 2.  RE: Stacking question, 2930M switches

    MVP GURU
    Posted Nov 06, 2019 09:29 AM

    Hi! what Switch is actually owning the Commander role?



  • 3.  RE: Stacking question, 2930M switches

    Posted Nov 06, 2019 09:30 AM

    Sw. 1 is commander, Sw. 2 is standby, Sw. 3 is member.



  • 4.  RE: Stacking question, 2930M switches
    Best Answer

    MVP GURU
    Posted Nov 06, 2019 02:05 PM
    HI! Given that your issue is between SW1 and SW3 and SW3 has the Member role...if you are going to reseat DAC Cable between SW3 and SW1 you will cause the stack to split in two unequal (in size) fragments...the larger one will contain Commander (SW1) and Standby (SW2)...the smaller one will contain the Member (SW3)...this one will become inactive...so connected user will suffer disconnections (that should be the expected behaviour). That's a reasonable approach if the purpose is to firmly reseat involved DAC Cable to exclude it's just a physical issue.


  • 5.  RE: Stacking question, 2930M switches

    Posted Nov 12, 2019 11:08 AM

    Can i ask when stacking 2930M swtiche using the DACS and the 2 port stacking module - should the cables "cross" 

     

    IE Switch 1 - Port 1 connects to Switch 2 Port 2

     

    Or should they be Switch 1 port 1 connects to Switch 2 port 1

     

    Many thanks



  • 6.  RE: Stacking question, 2930M switches

    MVP GURU
    Posted Nov 12, 2019 05:03 PM

    On Aruba 2930M - first thing first - you don't for a Backplane Stack by using "normal" DAC Cables but, instead, you must use special Stacking Cables (they look similar to DAC but they haven't the typical expected SFP+ form factor).

     

    So...on a two Members Backplane Stack you can use both Stacking Ports concurrently (each Stacking Module has 2 Stacking Ports) and you can do it by linking any-to-any:

     

    SW1 Stack Module Port 1 <--> Port 1 Stack Module SW2

    SW1 Stack Module Port 2 <--> Port 2 Stack Module SW2

     

    or:

     

    SW1 Stack Module Port 1 <--> Port 2 Stack Module SW2

    SW1 Stack Module Port 2 <--> Port 1 Stack Module SW2

     

    in any case you're forming a Ring Topology.

     

    It's clear that if you have Three Aruba 2930M you will be forced to a Chain Topology where:

     

    SW1 Stack Module Port 1 <--> Port 2 Stack Module SW2

    SW2 Stack Module Port 1 <--> Port 2 Stack Module SW3

    SW3 Stack Module Port 1 <--> Port 2 Stack Module SW1 (which closes the loop into SW1)

     

    or:

     

    SW1 Stack Module Port 1 <--> Port 1 Stack Module SW2

    SW2 Stack Module Port 2 <--> Port 2 Stack Module SW3

    SW3 Stack Module Port 1 <--> Port 2 Stack Module SW1 (which closes the loop into SW1)

     

     



  • 7.  RE: Stacking question, 2930M switches

    Posted Nov 13, 2019 03:21 AM

    Fantastic - thats as i expected as how i have set them up.

     

    Many thanks for your assistance



  • 8.  RE: Stacking question, 2930M switches

    Posted Nov 13, 2019 10:26 AM

    Do the ports have to match, or can you do:

     

    SW 1 port 1 --> SW 2 port 2

    SW 2 port 1 --> SW 3 port 2

    SW 3 port 1 --> SW 1 port 2?

     

    So "crossing over" every time you connect? (Btw is the logic same for VSF on 2930F)?



  • 9.  RE: Stacking question, 2930M switches

    MVP GURU
    Posted Nov 13, 2019 07:12 PM

    Aruba 2929 Backplane Stacking cabling: it can be any-to-any.

     

    So on a Three Member Stack you can have:

     

    SW 1 port 1 --> SW 2 port 2

    SW 2 port 1 --> SW 3 port 2

    SW 3 port 1 --> SW 1 port 2

     

    SW 1 port 1 --> SW 2 port 1

    SW 2 port 2 --> SW 3 port 2

    SW 3 port 1 --> SW 1 port 2

     

    SW 1 port 2 --> SW 2 port 2

    SW 2 port 1 --> SW 3 port 1

    SW 3 port 2 --> SW 1 port 1

     

    On a Two Member Stack:

     

    SW 1 port 1 --> SW 2 port 1

    SW 1 port 2 --> SW 2 port 2

     

    SW 1 port 1 --> SW 2 port 2

    SW 1 port 2 --> SW 2 port 1

     

    It's more a matter of having good stacking cabling on the backplane than respecting a particular connection pattern.



  • 10.  RE: Stacking question, 2930M switches

    Posted Jan 10, 2022 01:16 PM
    Hello ,
    I have 5 switches 2930M (JL322A) that I need to stack. I have JL325A stackable modules. Since this is the first time that I am doing this. Can you tell me the procedure (commands and steps).
    The switches are already linked together with the J9735A cable stack.
    
    Thank's a lot


    ------------------------------
    Mairie Slv
    ------------------------------



  • 11.  RE: Stacking question, 2930M switches

    MVP GURU
    Posted Jan 10, 2022 03:51 PM
    Hi! Given that you're trying to setup a Backplane Stack of Aruba 2930M switches, I suggest you to read the relevant parts of the guide published here:


    Focus on "Backplane Stacking" deployment, maintenance and troubleshooting. VSF is not relevant to your scenario (not supported on Aruba 2930M).





  • 12.  RE: Stacking question, 2930M switches

    Posted Jan 11, 2022 04:42 AM
    I will do that.
    Thank you Parnassus and have a good day.

    ------------------------------
    Mairie Slv
    ------------------------------



  • 13.  RE: Stacking question, 2930M switches

    Posted Jan 12, 2022 06:42 AM
    Replace stack cabel

    ------------------------------
    Steinar Grande
    ------------------------------



  • 14.  RE: Stacking question, 2930M switches

    MVP GURU
    Posted Jan 13, 2022 06:35 AM
    Hello Steinar Grande, I fear you replied to a 2 Years old post...

    ------------------------------
    Davide Poletto
    ------------------------------