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Virtual servers became down after configuring VMAC in HA mode


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Hi everyone ,


We do have two NetScaler in HA mode, SDXs 


we are having an issue most likely because of our network hardware compatibility , I'm not sure ,

however, when we do a fail over ,, the virtual servers change to down although the fail over successfully complete

the network interfaces have the same configuration for both devices , and we don't know how to fix this , 

so to overcome this issue, we do a force failover , and then swap the network cables from device 1 to device 2 ,, and verse versa in each failover .


and also I came across an article saying  VMAC could help in such situation/issue , and here we go to another issue , whenever we configure a VMAC, and we see the VMAC floating between the two Netscalers ,, 

again the virtual servers become down.. until we remove the VMAC , then they change to up again ,, 


I don't know from where to start since I'm fresh to Citrix/NetScaler 


please let me know if anyone faced the same issue before ?

thank you


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Looks like you're having ARP issues. Have you checked the ARP tables in the switches to make sure the ARP tables are being updated with the MAC of the new active instance after the failover? Some devices do not accept GARP, which is how the ADC broadcast the new MAC after the failover.

Usually we solve it by either allowing GARP or using VMACs.

VMACs are specially recommended in environments with lots of VIPs (hundreds or more), to avoid a GARP storm with each failover.


VMACs with SDX require an additional configuration at the SDX Management level. You have to enable the VRID both at SDX Management and the VPX instances.

Check this doc: https://docs.citrix.com/en-us/sdx/12/configuring-managing-netscaler-instance/configuring-vmac-on-interface.html


Hope it helps

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