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Difficulty: HardHybrid and VMware Cloud on AWS Migrations

An enterprise is migrating its legacy on-premises VMware vSphere workloads to a Multi-AZ VMware Cloud on AWS (VMC on AWS) SDDC. The SDDC is connected to the on-premises data center via AWS Direct Connect using a Direct Connect Gateway (DXGW) attached to a VMware Transit Connect (vTGW). The enterprise is using VMware HCX to extend several on-premises L2 VLANs to the SDDC.

During the migration, virtual machines (VMs) are moved using HCX Replication-Assisted vMotion (RAV). A set of migrated VMs on an extended network segment needs to communicate with database servers remaining on-premises that reside on a non-extended subnet. The network team reports that traffic from the migrated VMs to the on-premises database servers is experiencing high latency and routing loops. Diagnostics show that packets from the migrated VMs are traversing the HCX Network Extension (L2 path) back to the on-premises default gateway and then to the database servers, while return traffic is routing over the Direct Connect path.

Which solution will resolve the routing inefficiency and ensure optimal bidirectional path routing between the migrated VMs and the on-premises database servers?

  1. A
    Create a Route 53 Private Hosted Zone (PHZ) containing the database domain names and associate it with both the VMC on AWS SDDC VPC and the customer-managed VPC. Configure Route 53 Inbound and Outbound Resolvers to route database traffic directly over the Direct Connect connection.
  2. B
    Create an AWS Transit Gateway in the customer-managed AWS account, attach it to the VMware Transit Connect using a Transit Gateway Peering attachment, and configure static routing on the DXGW to forward the /32 host routes of the migrated VMs to the on-premises router.
  3. Enable Proximity Routing in the HCX Network Extension configuration. In the VMware Cloud on AWS console, configure Route Redistribution under the Transit Connect settings to enable the redistribution of HCX host routes (/32) to the Direct Connect Gateway. Ensure that the on-premises router is configured to accept and prioritize these host routes over the extended network's summary route.Answer
  4. D
    Configure a policy-based VPN between the HCX appliances to bypass the Direct Connect connection for data replication and live migration traffic. Implement an active-passive DNS routing policy using Route 53 to redirect database queries to a replicated standby database in a native AWS VPC.

Answer

The correct solution is to enable Proximity Routing in the HCX Network Extension configuration, and configure Route Redistribution under the Transit Connect settings in the VMware Cloud on AWS console to enable the redistribution of HCX host routes (/32) to the Direct Connect Gateway.
The correct solution involves enabling Proximity Routing in the HCX Network Extension. When Proximity Routing is enabled, the HCX appliance in the SDDC intercepts traffic from migrated VMs destined for non-extended subnets and redirects it to the SDDC routing path. To ensure bidirectional routing, the SDDC Tier-0 router must advertise /32 host routes of the migrated VMs to the on-premises router. This requires configuring Route Redistribution under the Transit Connect settings in the VMware Cloud on AWS console to propagate HCX host routes to the Direct Connect Gateway, and ensuring that the on-premises router prioritizes these specific host routes.

Step-by-Step Solution

1
Analyze the traffic flow and routing behavior between the migrated VMs (on the extended network) and the on-premises database servers (on a non-extended network).
Identify that outgoing traffic is hairpining through the L2 extended network, while return traffic is using the Direct Connect routed path, causing asymmetrical routing and high latency.
By default, the migrated VMs use their on-premises default gateway for all off-subnet traffic, which pulls packets back across the L2 extended network.
2
Enable HCX Proximity Routing on the extended network segment.
The SDDC HCX Network Extension appliance intercepts outgoing traffic destined for non-extended subnets and forwards it locally to the SDDC Tier-1/Tier-0 routing path.
Proximity Routing redirects traffic locally so that outgoing packets can utilize the low-latency Direct Connect routed path instead of crossing the L2 extension.
3
Configure Route Redistribution in the VMware Cloud on AWS SDDC console for Transit Connect.
Enable the redistribution of HCX host routes (/32) to propagate the individual host routes of migrated VMs to the Direct Connect Gateway (DXGW) and the on-premises router.
The on-premises router must receive these /32 host routes to know that the migrated VMs are located in the SDDC, ensuring return traffic is routed back via Direct Connect instead of the L2 extended network.

Key Concept

Ensuring optimal bidirectional routing for VMs migrated to VMware Cloud on AWS on extended L2 segments using HCX Proximity Routing and VMC route redistribution.
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Topics

Hybrid and VMware Cloud on AWS Migrations

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