Hello @WinTechie ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
Yes, it is possible. You can link a single virtual network with up to four ExpressRoute circuits in the same location or up to 16 ExpressRoute circuits in different peering locations.
Reference : https://video2.skills-academy.com/en-au/azure/expressroute/expressroute-faqs#can-i-have-one-virtual-network-connected-to-more-than-one-expressroute-circuit
Rather, it is strongly recommended that customers setup at least two ExpressRoute circuits to avoid single points of failure. Multiple ExpressRoute circuits from different peering locations or up to four connections from the same peering location can be connected to the same virtual network to provide high-availability in the case that a single circuit becomes unavailable. You can then assign higher weights to one of the local connections to prefer a specific circuit.
Reference : https://video2.skills-academy.com/en-au/azure/expressroute/expressroute-faqs#how-do-i-implement-redundancy-on-private-peering
Challenges of using multiple ExpressRoute circuits:
When you interconnect the same set of networks using more than one connection, you introduce parallel paths between the networks. Parallel paths, when not properly architected, could lead to asymmetrical routing. You can influence Azure to prefer one ExpressRoute circuit over another one using one of the following techniques (listed in the order of effectiveness):
- advertising more specific route over the preferred ExpressRoute circuit compared to other ExpressRoute circuit(s)
- configuring higher Connection Weight on the connection that links the virtual network to the preferred ExpressRoute circuit
- advertising the routes over less preferred ExpressRoute circuit with longer AS Path (AS Path prepend)
Once you take care of the above challenge, your approach should work without any issues.
Kindly let us know if the above helps or you need further assistance on this issue.
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