In this scenario, the issue arises from overlapping IP address ranges between the Transit VPC and the User VPC. Here's a detailed breakdown:
Understanding ERPs (Elastic Routing Prefixes):
The ERP for the Transit VPC is 10.1.1.0/25, which covers IP addresses from 10.1.1.0 to 10.1.1.127.
The ERP for the User VPC is 10.1.1.0/24, which covers IP addresses from 10.1.1.0 to 10.1.1.255.
IP Address Overlap:
Since 10.1.1.0/25 is a subset of 10.1.1.0/24, there is a significant overlap in the IP address ranges of these two ERPs.
This overlap can cause routing issues because the same IP address range is being used in both VPCs, leading to ambiguity in routing and communication.
Communication Issue:
When a VM in the User VPC tries to communicate with other resources, the network cannot accurately determine the correct route due to the overlapping IP address ranges.
This overlap prevents proper routing and results in the VM being unable to communicate with other resources as intended.
Resolution:
To resolve this issue, the ERPs must be in different CIDR ranges. This means the IP address ranges for the Transit VPC and the User VPC should not overlap.
For example, if the Transit VPC uses 10.1.1.0/25, the User VPC could use a different range such as 10.1.2.0/24 or any other range that does not overlap with 10.1.1.0/25.
By ensuring that the ERPs are in different CIDR ranges, the network can properly route traffic between the VPCs without any conflicts or ambiguities, thereby enabling the VM in the User VPC to communicate with other resources effectively.

Port Requirements: The specified ports (22, 2009, 2020, 2049, 3260, 9440) are commonly used for various services and require TCP communication.
Port 22: SSH
Port 2009: Used for Nutanix internal communication
Port 2020: Nutanix services
Port 2049: NFS
Port 3260: iSCSI
Port 9440: Nutanix Prism management
Communication Type: To ensure proper disaster recovery setup, bi-directional communication is needed to allow traffic to flow both from on-premises to Azure and vice versa.
TCP Protocol: These ports use the TCP protocol, which provides reliable communication between devices.
Conclusion: Creating a bi-directional (TCP) rule on the firewall allows the necessary communication for disaster recovery processes.
Reference:
Nutanix Networking and Security Documentation
Azure Networking Documentation

* Network Security Groups (NSGs):NSGs control the inbound and outbound traffic to and from Azure resources. For traffic between on-premises CVMs and NC2 CVMs in Azure, the NSGs associated with the Flow Gateway VM's Internal NICs must be configured to allow the required traffic.
* Editing NSGs:To enable traffic flow, specific rules must be added to the NSGs to permit traffic from the on-premises network to the NC2 environment. Thisincludes specifying the appropriate source and destination IP ranges and the necessary ports and protocols.
References:
* Azure Network Security Groups Documentation
* Nutanix NC2 Networking Configuration Guide

Equal-Cost Multi-Path (ECMP) Routing: ECMP allows multiple gateways to be used simultaneously for load balancing traffic across multiple paths. In this scenario, ECMP is configured to point to the external subnets in the Nutanix Transit VPC.
Traffic Distribution: All four Flow Gateway instances will be used to distribute the outgoing traffic from the application server based on the ECMP default route configuration. This ensures efficient load balancing and utilization of all available gateway resources.
Bidirectional Traffic: Both sending and receiving traffic will utilize all four Flow Gateway instances, ensuring high availability and performance for network-intensive applications.
Reference:
Nutanix NC2 Networking Guide
Azure Networking Documentation on ECMP

* Account Administrator Role:This role grants the necessary permissions for managing the Azure account, including the ability to open, close, or extend a support tunnel. These capabilities are crucial for the Nutanix Support team to perform diagnostics and troubleshooting efficiently.
* Permissions Included:The Account Administrator role encompasses broader account management rights, ensuring that the user can interact with various support and operational aspects of the NC2 environment within Azure.
References:
* Azure Role-Based Access Control (RBAC) Documentation
* Nutanix NC2 Support Tunnel Requirements