Professional Cloud ArchitectAnalyze and optimize technical and business processesHard
A large enterprise is migrating a legacy application that relies heavily on multicast communication for service discovery and inter-service messaging. The application is critical and cannot be refactored to use standard unicast or pub/sub mechanisms in the short term. The enterprise wants to lift and shift this application to Google Cloud while maintaining its existing multicast functionality. Which networking solution should they implement?
- AUse Shared VPC to allow the application to communicate across different projects with inherent multicast support.
- BDeploy the application on Compute Engine VMs within a standard Virtual Private Cloud (VPC) network and rely on Google's internal routing.
- CImplement a custom overlay network (e.g., using VXLAN or OpenVPN) on Compute Engine VMs to encapsulate and tunnel multicast traffic.
- DUtilize Cloud VPN tunnels to connect on-premises to a VPC network with custom routes for multicast traffic.
Show answer & explanationAnswer & explanation
Correct answer: C. Implement a custom overlay network (e.g., using VXLAN or OpenVPN) on Compute Engine VMs to encapsulate and tunnel multicast traffic.
Google Cloud's VPC networks do not natively support IP multicast routing. To lift and shift an application dependent on multicast, an overlay network solution (like VXLAN or OpenVPN) must be implemented on top of the VPC network. This encapsulates multicast traffic within unicast tunnels, allowing it to traverse the Google Cloud network infrastructure.
Why the other options are wrong
- A. Shared VPC allows network connectivity across projects but does not add native multicast support to the underlying VPC network, which still lacks this feature.
- B. Standard Google Cloud VPC networks do not support IP multicast routing, so this approach would fail.
- D. Cloud VPN tunnels do not inherently enable multicast routing within the Google Cloud VPC or between on-premises and cloud; they are for unicast traffic. Custom routes also apply to unicast.
Multicast on Google Cloud
Google Cloud VPC networks do not natively support IP multicast routing. Workarounds involve using overlay networks or refactoring applications to use unicast/pub/sub.
- Native multicast is not supported in Google Cloud VPC.
- Overlay networks (e.g., VXLAN, OpenVPN) can encapsulate multicast traffic over unicast.
- Refactoring to unicast or pub/sub (e.g., Cloud Pub/Sub) is the recommended long-term solution.
- Impacts legacy applications heavily reliant on multicast for service discovery or messaging.
Memory trick: No native multicast, so build a tunnel for the broadcast!