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MAD for a 2 NODE VSF on 2930F

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  • 1.  MAD for a 2 NODE VSF on 2930F

    Posted Aug 20, 2021 04:23 PM

    If I make a 2 member VSF from 2 2930F switches, it's a chain so it can't have 2 links, but I can have 2 ports be part of link 1 which makes it redundant to failure of one of the vsf links.

    vsf
    enable domain 2202
    member 1
    type "JL558A" mac-address 64e881-xxxxxx
    priority 127
    link 1 1/51-1/52
    link 1 name "I-Link1_1"
    link 2 name "I-Link1_2"
    exit
    member 2
    type "JL558A" mac-address 64e881-xxxxxx
    priority 128
    link 1 2/51-2/52
    link 1 name "I-Link2_1"
    link 2 name "I-Link2_2"
    exit
    port-speed 10g
    exit

    My question is, is there any point in setting up vlan-mad with a 2 node switch.  I'm not able to think of an example of how the 2 switches would loose contanct with each other and get in a split brain situation.

    If the argument is that vlan-mad is still necessary/a good idea, I assume there's no reason that I couldn't just skip having an unmanaged switch to connect the mad ports together and just connect them with an ethernet cable.  (So configure 1/1 and 2/1 as the MAD ports and connect them together)  Is that correct?



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    Adam Forsyth
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  • 2.  RE: MAD for a 2 NODE VSF on 2930F

    Posted Aug 21, 2021 09:57 AM
    Hello Adam,

    "My question is, is there any point in setting up vlan-mad with a 2 node switch.  I'm not able to think of an example of how the 2 switches would loose contanct with each other and get in a split brain situation."

    On the contrary: a 2 members VSF Stack can split in two fragments (Split Brain scenario) if VSF Link(s) goes down for any reason (Cables KO, VSF Ports KO, etc.) so it is highly recommendable to setup a MAD mechanism even if the VSF Stack is formed by just two chained members (Aruba 2930F VSF supported MAD methods via an upstream/downstream peer switch are: LLDP-MAD or VLAN MAD).




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    Davide Poletto
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  • 3.  RE: MAD for a 2 NODE VSF on 2930F

    Posted Aug 21, 2021 12:10 PM
    I guess I meant with 2 vsf links it wouldn't be a single failure that would cause split brain. It would take failure of 2 cables or 2 ports. And if one event is going to take out 2 cables what makes us think the same event won't take out the mad too?





  • 4.  RE: MAD for a 2 NODE VSF on 2930F

    Posted Aug 21, 2021 05:11 PM
    Hello Adam,

    You're correct, considering how you configured VSF Link(s) "it would take failure of 2 cables or 2 ports" (to cause a Split Brain), nevertheless a MAD mechanism should be configured as a safeguard against any possible scenario which would cause a Split Brain situation. That's a VSF best practice.

    "And if one event is going to take out 2 cables what makes us think the same event won't take out the mad too?"

    Potentially but not necessarily.


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    Davide Poletto
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