How to Plan a Reliable Cross-Cloud Private Network Across Alibaba Cloud, Azure, and Multi-Site Offices?

Check internal IP ranges and access scope before connecting Alibaba Cloud, Azure, and offices

Cloud environments provisioned at different times are often set up separately by different project teams or external software vendors, which commonly leaves two hidden pitfalls:

• Overlapping internal network address ranges across cloud environments or offices: Many cloud virtual networks are created directly with default 172.16.x.x or 10.0.x.x address ranges. While this causes no issues when used in isolation, overlapping address ranges prevent traffic from being routed accurately once multiple clouds and on-premises offices are connected into the same internal network. Before provisioning, we work with you and your cloud administrators to check your existing address inventory, sorting out conflicting test subnets wherever possible before interconnection and reserving room for future workloads (in-cloud subnet adjustments and cloud resource migrations are performed by the enterprise cloud administration team, while we assist with planning the interconnection scheme).
• Only open access between environments with genuine business communication: Multi-cloud networking does not require unrestricted any-to-any access across every cloud environment and branch office. Listing actual requirements upfront—such as "domestic R&D offices accessing the Hong Kong test cloud" or "the Germany office and Suzhou headquarters accessing the Frankfurt production cloud"—and enabling only necessary access relationships keeps the network both clear and secure.

Keep round-trip paths consistent and configure cross-cloud internal DNS resolution

In cross-cloud and cross-border connections, two details directly determine whether systems run reliably once connected:

1. Keep outbound request and return paths consistent (symmetric return routing): When an office or one cloud initiates a call to another cloud, return packets should travel back along the same corresponding channel through which the request was sent. If outbound traffic takes the accelerated internal network while return traffic detours over the public internet, firewalls or cloud security groups along the way will block the returning packets, causing the frustrating symptom where the network appears connected yet calls fail or run extremely slowly in one direction. When planning your routing (for industry context, see Microsoft's official tutorial on dynamic routing connections across clouds), we automatically manage primary and backup paths as well as symmetric return routing, so your staff do not need to manually maintain complex static routing tables.

2. Configure cross-cloud internal DNS resolution together: Many cloud databases and internal APIs are accessed using private domain names. Even when the network is connected, workloads still cannot make normal calls if office computers or servers in another cloud cannot resolve those internal domain names. During go-live, we work with your technical staff to configure cross-cloud internal DNS resolution and test actual connectivity speed and stability between each cloud environment and office.

How we connect multi-cloud and multi-site offices, and our approach in manufacturing projects

When connecting public clouds such as Alibaba Cloud and Azure into your enterprise internal network, we support deploying virtual access gateways directly inside your existing cloud environments or interconnecting with cloud platform gateways: there is no need to wait for lengthy cross-border physical dedicated line construction, provisioning is faster than traditional network dedicated lines, and bandwidth can be scaled on demand at any time during data migrations or peak business periods. For critical production cloud environments that cannot afford downtime, two virtual gateways can be configured in active-standby automatic failover to improve reliability.

Clarifying cloud platform billing and daily maintenance responsibilities

To keep financial budgeting and daily maintenance clear, we also clarify two points with you before launching cross-cloud networking (for a detailed breakdown of overall networking costs, see our guide to enterprise SD-WAN cost factors):

• Cloud platform charges are billed separately: Even when cross-cloud traffic travels over an internal network transmission channel, public cloud platforms such as Alibaba Cloud and Azure still bill your cloud account for cloud host or cloud gateway runtime charges and outbound data transfer fees according to their respective pricing rules. These charges belong to the cloud vendor's own bill and are calculated separately from our network service fees (if any item is agreed to be paid through us, it will be listed separately in the quote).
• Division of maintenance between in-cloud settings and cross-cloud channels: Security groups, subnets, and cloud server states inside each public cloud are managed by the enterprise's cloud administrators or software maintainers, while we handle daily operations and monitoring for the cross-region transmission channels, access gateway policies, and links connecting each public cloud and office location. If your enterprise adds a new cloud environment or opens a new office later on, it can quickly join the existing internal network by following the established onboarding steps.