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IP aliasing has been set on Ubuntu 16.04 VM which is running in Microsoft Azure environment. The IP address to the eth0 interface assigned is 192.168.0.6. IP has been assigned to the virtual interface eth0:0 is 192.168.0.7. But the IP address for virtual interafce eth0:0(192.168.0.7) is not pingable or reachable from the other VM's which are in the same subnet. The Virtual Machines are Classic VMS.

Please let me know how can I make this working or is it the limitation of Azure.

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Sorry about the delay. I've been testing this in my lab.

In brief, IP aliasing may not be able to work on Azure. The most similar workaround is deploying a VM with two NICs.

Actually, if you try to perform a network capture on the VM, you will find that the VM with secondary IP address is able to send out the packets. But there is no inbound traffics because Azure doesn't know the secondary address.

ARP This screenshot is captured on a VM in the same subnet with the machine with IP aliasing enabled. 10.0.15.10 is the primary address and 10.0.15.101 is the secondary address.

According to the screenshot above, the gateway handles all network traffic (Including communication in same subnet). And that's the root cause why the secondary IP address doesn't work. Any ARP request is answered by the gateway. But the gateway isn't aware of the secondary IP, so it can't reply the ARP request for secondary IP address.

So I try to add the secondary IP configuration to the NIC, but it's not supported by default.

feature

According to the error message, we need to register a new feature called "AllowMultipleIpConfigurationsPerNic".

When I run the command to register this feature, it is stuck in Pending state. And 2 days later, it is still in Pending state.

Pending

So, in conclusion, you may need to deploy a VM with two NICs as a workaround.

Hope these information helps.

  • Thank you very much for the reply. The information shared is very helpful to confirm, IP aliasing does not work in Azure. – yravi104 Oct 10 '16 at 11:26
  • I have created the Linux VM's with Multi NIC's and assigned the IP address in the same subnet on Azure. When I ping the secondary interface eth1 from the other machine in the network which is in same subnet, it is not pinging. So I have added the route for the multiple NIC's and it has started pinging.Please let me what is the reason for such behavior in Azure. – yravi104 Oct 10 '16 at 11:34

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