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How to connect an Azure ARM VNet to an ASM VNet using VNet Peering

4:25 pm in ARM, ASM, Azure, Azure virtual network, Cloud, DC, DNS, VNet peering by Wim Matthyssen

Hi all,

In this blog post I will show you how you can connect an Azure Resource Manager (ARM) virtual network (VNet) to a classic or Azure Service Manager (ASM) VNet using VNet Peering.

VNet Peering, which was made generally available (GA) on September 28th, is a mechanism that allows you to connect two VNets in the same region through the Azure backbone network as they were a single network. This means that you don’t need a VNet gateway anymore, like when you setup a VNet-to-VNet VPN connection. It will allow full connectivity between the entire address space of the peered VNets. So, for example when VNet peering is setup, all virtual machines in the peered VNets will be able to communicate with each other. If you’re interested you can read more about VNet Peering via following link: https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-peering-overview

Before we start setting things up, first some things to keep in mind:

  • VNet Peering requires that both VNets are located the same Azure region
  • The VNets must be in the same Azure Subscription (only for ARM – ASM VNet Peering)
  • The IP address space of both VNets must not overlap
  • Using your peer’s VNet gateway (UseRemoteGateways and AllowGatewayTransit settings) is not supported when peering with an ASM VNet
  • There is a small charge for data transferred between VNets using VNet Peering (inbound and outbound data transfer $ 0,01 per GB)
  • To be clear, you can find below a drawing of my ARM – ASM VNet Peering setup

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After all this is said and shown, we can start

1) First of all login to the Azure portal and sign in with your Azure account

2) Select Virtual Networks

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3) Select your ARM VNet (in my case AZU-Vnet-ARM)

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4) Click Peerings (like you can see there is one connected device AZU-APP-01)

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5) Click Add

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6) In the Add Peering blade, name your link (in my case LinkToVNetASM). Under Peer details select Classic. Choose the correct Subscription and the ASM Virtual Network you want to peer with. Leave Allow virtual network access Enabled, this will allow communication between the two virtual networks. Then click OK

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7) After clicking OK the peering link will be created

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8) When done, the two virtual networks are peered and you will see the PEERING STATUS between the two virtual networks is in a Connected state

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9) Like you can see, both VMs can ping each other. Don’t forget to allow ping through the Windows Firewall

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10) After adding AZU-DC-01 (10.0.1.36) as DNS server to the AZU-Vnet-ARM VNet, I was able to add AZU-APP-01 to the azuvlab.local domain which was created an AZU-DC-01

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This concludes this blog post. If you have any questions don’t hesitate to contact me via twitter.

Wim Matthyssen (@wmatthyssen)

Replica DCs on Azure – Switch DNS servers for the VNet

7:18 am in Azure, Cloud, DC, DNS, hybrid cloud, IaaS, Replica DC, W2K12R2 by Wim Matthyssen

This blog post is part of the step-by-step to deploy replica domain controllers (DCs) on Microsoft Azure which can be found here: http://scug.be/wim/2015/09/28/deploying-replica-dcs-in-windows-azure/

After we successfully installed both IaaS virtual machines (VMs) as DCs there are still some Azure related actions we can perform. One of them is changing the DNS servers used in the VNet (AZU-VNET-01) to primary use the DNS installed on both IaaS DCs. By doing this we will minimize the data (DNS related actions) out of the Azure data center, which will reduce Azure network costs. We can do this changes through use of the Azure Classic Portal or via the network configuration file (NetworkConfig.xml). I will show both steps below, so let’s get started.

By making use of the Azure Classic Portal

1) Logon to the Azure Classic Portal as a Service administrator or Co-administrator

2) In the navigation pane, click Networks and then click the name of your VNet (AZU-VNET-1)

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3) Click Configure

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4) In the dns servers section, delete the on premise DC (GR-DC-01) by clicking the X next to the IP ADDRESS

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5) To add and register both Azure IaaS DNS servers (AZGR-DC-01 and AZGR-DC-02) with the VNet and Azure, just type their name and IP Address in the boxes. I will also add the on premise DNS server (GR-DC-01) as third failback DNS server. When added click Save

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6) When asked click YES, this will start updating the VNet

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7) When finished successfully, click OK

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8) When the DNS list is updated, we must restart all IaaS VMs (AZGR-DC-01 and AZGR-DC-02) connected to the VNet, so they can pick up the new DNS settings

Before the reboot:

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After the reboot:

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9) To check if DNS is working like it should after the changes, ping the on premise DC (GR-DC-01). If all is OK, you should get replies like shown it the below screenshot

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By making use of the network configuration file

1) Logon to the Azure Classic Portal as a Service administrator or Co-administrator

2) In the navigation pane, click Networks, click the name of your VNet (AZU-VNET-1) to select it and at the bottom of the screen click EXPORT

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3) Select your SUBSCRIPTION and click het check mark button

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4) The NetworkConfig.xml file will be downloaded. When finished click View downloads

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5) Click Open folder

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6) Right click the NetworkConfig.xml file and select Edit

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7) You can see in the original file there is just one DNS servers used (GR-DC-01 – 192.168.2.4)

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8) Change the DNS servers like in the screenshot below and save the file

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9) Go back to the Azure portal, click NEW at the bottom, click NETWORK SERVICES, click VIRTUAL NETWORK and then click IMPORT CONFIGURATION

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10) Browse the changed NetworkConfig.xml file and click the arrow

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11) Verify the changes and press the check mark button at the bottom if all is fine

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12) The import will start

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13) When the import is successfully finish press the OK button

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14) Like you can see, the DNS servers (AZGR-DC-01 and AZGR-DC-02) are added

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15) Reboot all IaaS VMs connected to the VNet to adjust their DNS settings

That ends this part of the series. I hope it’s useful, till next time!

Wim Matthyssen (@wmatthyssen)