Azure Cross-region VNet connectivity with on-premises access - azure

I have one Vnet (VNet1) in region 1 which is connected to on-premises using s2s VPN. I have got this peered with a second Vnet (Vnet2) in the same region following hub-spoke network pattern. VNet2 is configured to use Vnet1 Gateway transit for on-premises connectivity.
Now I have a third Vnet (Vnet3) in region3 which is also a spoke for Vnet1. Since this is in a different region I used VNet-VNet VPN (since Global Vnet peering doesn't support transitive gateway.) I reused the existing VPN that was used for S2S on Vnet1 for the Vnet1-Vnet3 connectivity.
The question is how do I support transit Gateway feature from VNet3->Vnet1 to achieve on-premises connectivity? To test it out I have setup UDR to route all traffic from Vnet3 to VPN Gateway. So this should bring the traffic to Vnet1. But this doesn't allow me to reach on-premises. Shouldn't Vnet1 routes know that the traffic is for on-premises and route it accordingly? Do I need some kind of NVA in Vnet1?
Any help would be appreciated.

If you want to create multi VPNs between the vnets, first you should take care and pay attention to the limitations of it. See limitations for multi VPN. And you also can follow the steps to create the multi VPNs.

Related

Connect endpoint VPN client to multiple vnets in azure

I have three vnets that I would like to make accessible to end users. The three vnets can talk to each other via peering. If I setup a VPN gateway, the VPN can only connect to the vnet that the gateway is setup to.
I have the allow gateway transit, use remote gateways as well as allow forwarded traffic enabled. I've also redownloaded the VPN client.
Is there an option I'm missing that will let the VPN clients connect to all three vnets?
If you use a Virtual Network Gateway to send on-premises traffic transitively to a peered VNet, the peered VNet IP range for the on-premises VPN device must be set to 'interesting' traffic. Otherwise, your on-premises resources won't be able to communicate with resources in the peered VNet.
Ref:https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-manage-peering#create-a-peering

Routing traffic in Azure VPN

I have 3 VNets, 3 Point-2-Site VPN Gateways, one for each Vnet, and VNet peering is setup as below image.
What I want to achieve is:
If I use VPN1, I can ping all VMs in all 3 VNets.
If I use VPN2, I can only ping VMs in VNet 2 and 1.
If I use VPN3, I can only ping VMs in VNet 3 and 1.
As I understand, to achieve 1, I have to allow forwarded traffic in both peering. But then, 2 and 3 cannot be fulfilled - I can ping all VMs regardless what VPN I use. Is that correct?
What should be the right way to do this?
Update: For more details, here's my use case:
In VNet 1, I have an Intranet server, which should be available for everyone.
In VNet 2, I have a development server.
In VNet 3, I have a test server.
A manager should be able to access all servers --> VPN1.
A developer should be able to access the Intranet and the Dev server --> VPN2
A tester should be able to access the Intranet and the Test server --> VPN3
For your requirements, I believe you could achieve it via configuring VPN gateway transit for virtual network peering a hub-and-spoke network architecture. In this network architecture, you need to deploy one VPN gateway in the VNet1(as the hub) and peer with the other two VNets(as the spoke) instead of deploying VPN gateways in every spoke virtual network. Routes to the gateway-connected virtual networks or on-premises networks will propagate to the routing tables for the peered virtual networks using gateway transit.
The following diagram shows how gateway transit works with virtual network peering.
In this case, you could configure the VNet1 peers with VNet2 and VNet1 peers with VNet3 each other.
On the peering from VNet1 to VNet2 and VNet1 to VNet3, enable the Allow gateway transit option. On the peering from VNet2 to VNet1 and VNet3 to VNet1, set the Use remote gateways option.

VPN Gateway peering

I know Virtual network peering is a thing but just like that is VPN Gateway peering is a thing? if so then if a VPN Gateway(A) with AD AuthN(OpenVPN SSL tunnel type) and a VPN Gateway(B) with Azure certificate-based authN with SSTP(SSL) tunnel type, Can A and B be peered.
Questions based on above:
Do we have to do S2S peering setup between A and B with manual routing for each to access any resource from A to B and vice versa?
What is the limitation of this setup and advantages(if any)?
Will it be called a Hybrid solution?
If you have two VPN gateways in Azure, you could configure the VNet-to-VNet connections to connect Azure VNets to each other. You don't need manual routing. VNet-to-VNet supports connecting virtual networks. Connecting multiple Azure virtual networks together doesn't require a VPN device unless cross-premises connectivity is required.
When you connect a virtual network to another virtual network with a
VNet-to-VNet connection type (VNet2VNet), it's similar to creating a
Site-to-Site IPsec connection to an on-premises location. Both
connection types use a VPN gateway to provide a secure tunnel with
IPsec/IKE and function the same way when communicating. However, they
differ in the way the local network gateway is configured.
When you create a VNet-to-VNet connection, the local network gateway
address space is automatically created and populated. If you update
the address space for one VNet, the other VNet automatically routes to
the updated address space. It's typically faster and easier to create
a VNet-to-VNet connection than a Site-to-Site connection.
You could read the document for more details.

Question concerning forward traffic on Azure Virtual Networks

I have a routing problem which I am struggling to solve in the Azure cloud platform concerning traffic that needs to be routed from one vnet to another vnet via another vnet and two VPN tunnels.
Here is a description of the set-up:
I do have two Azure Virtual Networks (VNET1 and VNET2) that each one has its own route-based Azure VPN Gateway and one 3rd party virtual network (VNET3) which is connected to the first Azure virtual network VNTE1 via an IPsec VPN tunnel. Below are the address spaces of all 3 virtual networks.
VNET1 10.20.0.0/16 (Azure vnet)
VNET2 10.30.0.0/16 (Azure vnet)
VNET3 10.0.0.0/12 (3rd party vnet)
Here is what I can do:
The VNET1 is connected via an IPsec VPN tunnel with the VNET3. Thus I am able to ping from a VM in the VNET1 10.20.10.5 a VM in the VNET3 10.0.0.1 and they can ping me back.
The VNET1 is connected via an IPsec VPN tunnel with VNET2. Thus, I am able to ping from a VM in the VNET1 10.20.10.5 a VM in the VNET2 10.30.10.5
Here what i cannot do:
I cannot ping from a VM in the VNET2 10.30.10.5 the VM in VNET3 10.0.0.1.
Here is what I tried to do to solve the problem without any success so far:
My assumption is that the network VNET2 does not know how to route the traffic to the network VNET3. Thus, I created an Azure Route table and I assigned the route table to the subnet 10.30.10.0/24 and I created the rule that all the traffic to the network 10.0.0.0/12 should be routed to the VPN GateWay of the VNTE2. My expectation is that once the traffic will go to the GW it will reach the VNET1 which knows how to route it to the VNET3. This didn't work.
Although I think is not needed since VNET1 already knows how to route the traffic to the VNET3 I have also created a routing table for 10.0.0.0/12 similar to the one above. This didn't help either.
Am I missing a route somewhere, If so which rule and where? Or do I even need to have a VM acting as a router? (I hope not)
I think your issue is the limitation of Azure Virtual Gateway:
The on-premises networks connecting through policy-based VPN devices with this mechanism can only connect to the Azure virtual network; they cannot transit to other on-premises networks or virtual networks via the same Azure VPN gateway.
https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-connect-multiple-policybased-rm-ps
So, even if you use the same VPN Gateway to connect with VNET 3 and VNET 2, by design VNET 3 and VNET 2 cannot communicate.
To resolve this issue, I recommend to use peering. Your configuration is similar to classic Hub-Spoke topology. Your VNET1 is Hub, VNET2 is Spoke, VNET3 is kind of "on-prem".
No changes needed to configuration between VNET1 and VNET3. You need to establish peering between VNET1 and VNET2 and backwards and apply following configuration:
Configure the peering connection in the hub to allow gateway transit.
Configure the peering connection in each spoke to use remote gateways.
Configure all peering connections to allow forwarded traffic.
https://learn.microsoft.com/en-us/azure/architecture/reference-architectures/hybrid-networking/hub-spoke
In this case, VNET3 will be able to communicate with HUB (VNET1) and all spokes (VNET2 and any others connected to VNET1). VNET2 can communication with HUB (VNET1) and on-prem (VNET3) when the tunnel is up.
Warning: Spokes are not able to communicate between each other without a forwarding gateway in HUB, i.e. if you add VNET4 with peering to and from VNET1, VNET4 will not able to ping VMs in VNET2. But they could communicate with HUB and on-prem without any additional appliances.

How to connect 2 cross region azure vnet using express route

I have one vnet in Australia East and another in Australia southeast
I need minimum latency setup between these 2 regions.
I am looking at ER connection to both VNET but cant find any detailed guide on this. Traffic will be bidirectional.
Please suggest if someone carried out something similar
Thanks
There are three options to achieve connecting Vnet's in different regions:
Global VNET peering
VNET-to-VNET connection
Expressroute
As for the question,
How to connect 2 cross region azure Vnet using express route ?
Each VNET that is connected to an Expressroute circuit, becomes part of the same routing domain. This means that each VNET that is connected to Expressroute, regardless of whether it is in the same region or in a different region, will have connectivity to each other.
The connection between the two gateways would happen at the peering location, but would not go over the peered network. Meaning, the connection stays on the Microsoft network, but the hairpin happens at the peering location.
Reference: How to Link Vnet to ExpressRoute Circuit

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