AWS Certified Advanced Networking – Specialty (ANS-C01)Network DesignMedium
A financial institution is migrating a legacy mainframe application that relies heavily on IP multicast for service discovery and inter-process communication to AWS. The application will be deployed across multiple EC2 instances in different subnets within a single VPC. The security team insists on keeping the application in a private subnet and only allowing necessary traffic. How can multicast traffic be supported efficiently and securely within this AWS VPC?
- AUse VPC peering to connect subnets and configure IGMP snooping.
- BCreate a Site-to-Site VPN connection and tunnel multicast traffic.
- CDeploy a custom multicast routing daemon on an EC2 instance.
- DUtilize AWS Transit Gateway Multicast domains within the VPC.
Show answer & explanationAnswer & explanation
Correct answer: D. Utilize AWS Transit Gateway Multicast domains within the VPC.
AWS Transit Gateway Multicast allows customers to natively enable IP multicast across thousands of Amazon VPCs and on-premises networks. Within a single VPC, it enables multicast routing between subnets, which is a key requirement for legacy applications relying on multicast. This provides a managed, scalable, and secure solution.
Why the other options are wrong
- A. VPC peering connects two VPCs, not subnets within a single VPC, and AWS does not support IGMP snooping natively within VPCs.
- B. Site-to-Site VPN is for connecting on-premises networks to AWS, not for enabling multicast within a single VPC or between subnets.
- C. Deploying a custom multicast routing daemon is possible but adds operational complexity, requires manual configuration, and is not a native AWS-managed solution for scalable multicast.
Transit Gateway Multicast
A feature of AWS Transit Gateway that enables native IP multicast routing between subnets within a VPC or across multiple VPCs and on-premises networks.
- Supports IP multicast natively in AWS.
- Works within a single VPC or across multiple.
- Managed service, reduces operational overhead.
- Crucial for migrating legacy applications needing multicast.
Memory trick: Transit Gateway's the multicast key, for legacy apps, it sets traffic free!