ExpressRoute Circuit Sharing Feasibility Assessment

Hello Jagadhish Babu Subramaniyan ,

Welcome to the Microsoft Q&A and thank you for posting your questions here.

I understand that you would like to affirm ExpressRoute Circuit Sharing Feasibility Assessment.

Yes, it is technically feasible. A single ExpressRoute circuit can be linked to multiple Azure VNets, including VNets in different subscriptions, by using ExpressRoute circuit authorization. However, the circuit remains a shared 1 Gbps circuit, so Partner 1, Partner 2, and Partner 3 do not each receive dedicated 1 Gbps capacity. All traffic shares the same purchased circuit bandwidth. - https://learn.microsoft.com/en-us/azure/expressroute/expressroute-howto-linkvnet-portal-resource-manager, and https://learn.microsoft.com/en-us/azure/expressroute/expressroute-circuit-peerings gives you more insights.

My recommended solution is to implement the shared circuit only if the connectivity provider/customer-edge design enforces strong separation between the partners using VRFs, VLANs, MPLS L3VPN, firewalls, route filtering, and BGP controls. Azure allows multiple VNet connections to an ExpressRoute circuit, but the partner traffic isolation must be designed and operated by the provider/customer network, not assumed automatically from Azure private peering. - https://learn.microsoft.com/en-us/azure/expressroute/expressroute-howto-linkvnet-portal-resource-manager, and https://learn.microsoft.com/en-us/azure/expressroute/expressroute-circuit-peerings also give more details.

I hope this is helpful. Please! Do not hesitate to let me know if you have any other questions, steps or clarifications.

Please do not close the thread by upvoting and accepting the answer if any part of it is helpful.

Hi ,

Thanks for reaching out to Microsoft Q&A.

Yes, a single 1gbps azure expressroute circuit can be shared across multiple business partners via a common connectivity provider and shared customer edge infra but it depends on how it is architected and governed. This is typically done using expressroute global reach, virtual network gateways, or NVAs to segment traffic, combined with VRFs or VLAN separation on the provider/edge side to isolate each partner. The key constraints are bandwidth contention (all partners share the same 1 Gbps pipe), strict routing and security isolation, and commercial/legal considerations since ExpressRoute circuits are tied to a single subscription owner. In practice, this model works if there is clear traffic segmentation, QoS enforcement, and agreement on usage, but for production-grade isolation and predictable performance, separate circuits or bandwidth upgrades are often recommended.

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