Continuing with networking in Azure, today I want to talk about how extend the subnets in Azure with VXLAN. To those who do not know VXLAN, it proposes to generate a virtual network to overlap a LAN which will work as base. VXLAN technology uses a layer 3 technology, in order to extend the network, as it shows the following diagram, where the same subnet exists on both sides (Azure and OnPrem):
So here the key is that you need a tunel between Azure and OnPrem in order to exchange traffic, but also take into account the following:
- IP addresses of on-premises hosts are configured as additional IP addresses on the Network Interface Card (NIC) of the Azure VM (using Azure orchestration system);
- IP addresses of Azure hosts are configured as additional IP addresses of the NIC of on-premises VM.
Whenever an on-premises host tries to reach an Azure VM it sends out an ARP request, and the on-premises Extended Network VM replies to it.
Whenever an Azure VM tries to reach an on-premises host, the Azure Virtual Router sends the traffic to the local IP address which is owned by the Azure VM running Extended Network code.
Take care and happy networking!
Albandrod's Memory 