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Difficulty: HardOptimizing Network Performance and Latency

An autonomous vehicle telemetry company collects high-frequency sensor data from test vehicles. The data is uploaded to a central on-premises operations center and then replicated to AWS. The AWS environment consists of a primary VPC and 33 spoke VPCs in the `us-west-2` Region, all connected via an AWS Transit Gateway. The on-premises operations center connects to AWS via a 10 Gbps10\text{ Gbps} AWS Direct Connect connection using a Private Virtual Interface (Private VIF) terminated at a Virtual Private Gateway (VGW) in the primary VPC. Telemetry files average 120 MB120\text{ MB} in size and are uploaded via HTTPS. During peak test hours, uploads experience high latency and packet retransmissions, and DNS queries for the internal ingestion API endpoints fail intermittently or take too long to resolve from the spoke VPCs. The solution must maximize throughput, minimize latency, ensure high availability, and avoid unnecessary inter-VPC network hops for DNS resolution. Which two actions should the solutions architect take to meet these requirements?

  1. Configure a Transit Virtual Interface (Transit VIF) on the Direct Connect connection, associate it with a Direct Connect Gateway connected to the Transit Gateway, and enable Jumbo Frames (MTU 90019001) end-to-end on the Direct Connect connection and Transit Gateway attachments.Answer
  2. Associate the Route 53 Private Hosted Zone hosting the telemetry endpoints directly with all spoke VPCs to enable local DNS resolution inside each VPC.Answer
  3. C
    Configure a Direct Connect Gateway to route transitive traffic directly between the spoke VPCs, bypassing the Transit Gateway to reduce inter-VPC routing overhead.
  4. D
    Associate the Route 53 Private Hosted Zone only with the primary VPC, and route all spoke VPC DNS queries to the primary VPC's inbound resolver endpoint over Transit Gateway attachments.
  5. E
    Centralize all outbound public traffic by routing it through a single NAT Gateway deployed in 11 Availability Zone of the primary VPC to simplify route table management.
  6. F
    Deploy an Application Load Balancer in the primary VPC to forward ingestion traffic, relying on its default auto-scaling behavior to absorb sudden, massive spikes in telemetry uploads.

Answer

Configure a Transit Virtual Interface (Transit VIF) on the Direct Connect connection with Jumbo Frames (MTU 90019001) enabled end-to-end, and associate the Route 53 Private Hosted Zone directly with all spoke VPCs.
Configuring a Transit VIF and enabling Jumbo Frames (MTU 90019001) end-to-end reduces packet overhead and TCP fragmentation, maximizing throughput for large files over Direct Connect. Associating the Route 53 Private Hosted Zone directly with all spoke VPCs enables local DNS resolution via the local Route 53 Resolver, eliminating the latency and overhead of forwarding queries transitively across VPCs.

Step-by-Step Solution

1
Migrate the Direct Connect connection from a Private VIF to a Transit VIF connected to a Direct Connect Gateway.
Enables connectivity to a Transit Gateway, which supports multi-VPC routing and Jumbo Frames.
Transit VIFs and Transit Gateways support MTU up to 90019001 (Jumbo Frames), which reduces packet overhead and TCP retransmissions for large file transfers.
2
Enable Jumbo Frames (MTU 90019001) end-to-end across the Direct Connect VIF, Transit Gateway, and VPC route tables.
Increases the maximum transmission unit size to 90019001 bytes.
Replicating 120 MB120\text{ MB} files over HTTPS is highly throughput-dependent. Increasing the MTU minimizes packet fragmentation and header overhead.
3
Associate the Route 53 Private Hosted Zone directly with all spoke VPCs.
Enables local DNS resolution inside each spoke VPC via the Route 53 Resolver.
Local DNS resolution avoids transitive DNS query latency and network hops through Transit Gateway to inbound endpoints.

Key Concept

Optimizing network performance for large file transfers involves maximizing MTU sizes (Jumbo Frames) along the network path and localizing DNS resolution to avoid unnecessary transit latency.
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Topics

Optimizing Network Performance and Latency