In a Hub and Spoke architecture, what is the limit of network prefixes learned by Hub?

Cristiano da Silva Azevedo 21 Reputation points
2023-05-16T21:20:30.3366667+00:00

Hello guys,

My question is about ad limits learned in peering between VNETs..

Considering that I can have 1000 private endpoints per VNET, and each of them generates a /32 route to Hub, I would like to know how the limit of routes learned by the Hub would be handled. Please consider a scenario with multiple Spokes making use of hundreds of private endpoints.

I found the documentation below but it wasn't clear to me:

https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/azure-subscription-service-limits?toc=%2Fazure%2Fvirtual-network%2Ftoc.json#networking-limits

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Accepted answer
  1. KapilAnanth-MSFT 38,791 Reputation points Microsoft Employee
    2023-05-17T04:09:07.97+00:00

    @Anonymous

    Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

    I understand that you would like to know the limits regarding no. of routes advertised and learned between a VNet Peering.

    I am afraid I did not understand the part, "each of them generates a /32 route to Hub".

    • I am not aware of this observation.
    • What actually happens when you create a Private Endpoint in any virtual network is that the default route table of the subnet in which it is created, includes a /32 route with a next hop type of InterfaceEndpoint, not Hub
      • And this is done so that the PE's NIC resource can communicate to the PaaS resource (this is all abstracted)
    • And as for limits for the number of routes learned between Vnets in a Peering, there are no limits
    • The entire address range of the Spoke VNet will be learned by the Hub VNet should they be connected by VNet Peering.

    Kindly let us know if this helps or you need further assistance on this issue.

    Thanks,

    Kapil


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    1 person found this answer helpful.

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