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AliErkilic-5493 asked AndreasBaumgarten commented

VNET ARP Issue

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?

azure-virtual-machinesazure-virtual-network
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Hi @AliErkilic-5493 ,

Did the answer work for you? Are there any additional questions to this topic?

If you found the answer helpful, it would be great if you please mark it "Accept as answer". This will help others to find answers in Q&A

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Regards
Andreas Baumgarten

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AndreasBaumgarten answered AndreasBaumgarten edited

Hi @AliErkilic-5493 ,

if I remember right ARP and GARP are using broadcast.
Here Microsoft confirms broadcast and multicast are not supported in an Azure vNet.
https://docs.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/


(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten

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