2 hubs and vnet peering with expressroute

Question

Hello,

We are working on the design phase of our vnets and its connectivity to Expressroute.
We have several stakeholders that require Expressroute connectivity and our in the same AD domain etc. So the most logical scenario would be to use the hub-and-spoke with a shared expressroute.

However, one of the stakeholders would like their own hub as well. My question is, can you use vnet peering as follows:

Stakeholder VM vnet peered to stakeholder vnet hub peered to central hub vnet with expressroute. Will the expressroute connectivity work in this case?

Br,
Jasper

Answer 1

This scenario should be possible as long you get the routing sorted from Azure to on-premises networks and back from on-premises network to Azure networks.
You have 2 helpful options in the configuration of the vnet peerings: "Allow Gateway Transit" and "Use Remote Gateway" on the "Azure part". The routing on-premises you have to get sorted by adding the appropriate routes to the Azure vNets.

Maybe this is helpful.

Regards

Andreas Baumgarten

(Please don't forget to Accept as answer if the reply is helpful)

Answer 2

As long as you only have 1 Gateway (VPN or ExpressRoute) everything should work fine. The major limit with VNET Peering is that it can only access a gateway in 1 direction (Gateway Transit / Remote Gateways).

You might also want to look into Azure WAN

Answer 3

@Jasper Van Damme ,
You may connect another HUB vNet to same ER Circuit with the ER authorisation [ Default 10 for Standard ER Circuit ] and limit can be extended with a request to Microsoft. However, Please note both HUBs will be part of same routing domain .

https://learn.microsoft.com/en-us/azure/expressroute/expressroute-faqs#are-virtual-networks-connected-to-the-same-circuit-isolated-from-each-other