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Description of Problem :
This issues issue is realized when there exists both :
- a A VNet that is peered to the sharedservices VNet with gateway transit enabled thru ExpressRoute ExpressRoute.
- Additionally a A VM with an external IP that is being requested from the Cornell campus network.
With all of these pieces in place, packets sent from campus to the external IP will return to campus via the ExpressRoute and be dropped by the initiating host.
Solution: To get around or avoid this issue:
- we We create two subnets in the customer VNet - one "private", one "public".
- a A user defined route (UDR) will need to be created and then associated with the public subnet.
- The UDR will list all campus IP ranges with a next hop of "Internet".
Caveat: an additional caveat exists with this "solution":
- With the UDR in place the opposite asymmetric route will be true.
- A campus network system with a public IP, trying to reach the "10 space" address of an Azure VM on the subscriptions subscription's public subnet, will fail.
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