VNET ARP Issue

Question

We have a 3 Azure VM PostgreSQL cluster under the same subnet. We want to use Pgpool and connect to the master node through a delegate IP (virtual IP). However, when a node gets the delegate IP only that node can PING it, other 2 nodes can’t see this IP. We think that the problem is related to ARP and read somewhere that ARP is blocked on Azure Vnet. Is this true? How can we enable it?

Answer 1

Hi @Ali Erkilic ,

if I remember right ARP and GARP are using broadcast.
Here Microsoft confirms broadcast and multicast are not supported in an Azure vNet.
https://learn.microsoft.com/en-us/azure/virtual-network/virtual-networks-faq#do-vnets-support-multicast-or-broadcast

Maybe an Internal Load Balancer is helpful in your scenario?
https://azure.microsoft.com/de-de/blog/internal-load-balancing/

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Regards
Andreas Baumgarten