AWS Certified Advanced Networking – Specialty (ANS-C01)Network Management and OperationsMedium
A global enterprise is migrating a legacy application to AWS. The application relies on multicast for service discovery and data distribution among its backend components. The new architecture uses multiple VPCs connected via AWS Transit Gateway. The network architect needs to enable multicast communication between specific EC2 instances located in different subnets across these Transit Gateway-attached VPCs. Which AWS service and configuration is required to support this multicast traffic flow?
- AAWS Direct Connect Gateway with BGP multicast routes.
- BVPC Peering with IGMP snooping enabled on subnets.
- CAWS Transit Gateway with multicast domains configured.
- DAWS Global Accelerator with custom routing.
Show answer & explanationAnswer & explanation
Correct answer: C. AWS Transit Gateway with multicast domains configured.
AWS Transit Gateway supports multicast routing, allowing multicast traffic to be sent from a source in one VPC to multiple destinations in other VPCs attached to the same Transit Gateway. This is achieved by creating Transit Gateway multicast domains and associating subnets and EC2 instances with these domains to act as members or sources for multicast groups.
Why the other options are wrong
- A. AWS Direct Connect Gateway is for connecting on-premises networks to AWS VPCs and does not support multicast routing in this manner for inter-VPC communication.
- B. VPC Peering does not inherently support multicast routing; it's a unicast-only connection. IGMP snooping is a layer 2 feature for switches, not directly applicable for inter-VPC routing.
- D. AWS Global Accelerator provides static IP addresses and optimizes unicast traffic routing over the AWS global network; it does not handle multicast.
Transit Gateway Multicast
AWS Transit Gateway's capability to route multicast traffic between VPCs by creating multicast domains and associating subnets/instances as sources or members.
- Enables multicast across VPCs.
- Requires Transit Gateway multicast domains.
- Supports legacy applications needing multicast.
Memory trick: For VPC multicast, the Transit Gateway is your central director.