AWS Direct Connect — Definitive Guide to Dedicated Low-Latency Hybrid Connectivity
This extensive guide explains how AWS Direct Connect works, architecture patterns, VIF options (Private/Public/Transit), MACsec encryption, pricing considerations, monitoring, HA best practices, real-world use cases, and hands-on troubleshooting using AWS CLI, PowerShell-style examples, and router BGP configurations. Internal resources: CloudKnowledge: Networking & Connectivity.
Short URL suggestion: cloudknowledge.in/aws-direct-connect
Introduction: What is AWS Direct Connect?
AWS Direct Connect is a fully-managed network service from Amazon Web Services that allows you to establish a dedicated physical network connection between your on-premises environment (data center or colocation) and AWS. Unlike public internet connections, Direct Connect traffic traverses private, managed circuits — providing predictable, lower latency, and higher throughput connectivity for enterprise workloads.
- Dedicated physical connectivity (1Gbps, 10Gbps, 100Gbps) or hosted options for smaller bandwidths.
- Supports Private, Public, and Transit Virtual Interfaces (VIFs).
- Integrates with Direct Connect Gateway and AWS Transit Gateway for multi-VPC connectivity.
- Optional MACsec (Layer 2) for link encryption on supported locations and port speeds.
2. Core Benefits of AWS Direct Connect
The main motivations for adopting AWS Direct Connect are predictable performance, cost optimization for large data transfers, and stronger security posture for sensitive workloads.
Dedicated Bandwidth & Predictable Performance
Direct physical ports (1G/10G/100G) provide deterministic bandwidth and lower jitter vs. public internet. For latency-sensitive applications (financial trading, real-time analytics), this predictability is critical.
- Throughput: Scales via LAG (Link Aggregation Group).
- Latency: Typically lower and more consistent than internet links.
Security & Compliance
Traffic does not traverse the public internet. For added security, MACsec provides L2 encryption on 10G/100G ports where supported. This helps meet compliance requirements for regulated industries.
- Best for hybrid cloud architectures, database replication, media ingest, and large-scale migrations.
- Cost-effective for heavy outbound data transfer (reduced DTO vs internet).
- Works with AWS services via Public VIF for public endpoints (S3, DynamoDB) and Private VIF for VPC access.
3. How AWS Direct Connect Works — Components & Flow
At a high level, you order a Direct Connect port (dedicated or hosted) at an AWS Direct Connect location (colocation facility). A cross-connect is provisioned between your equipment and AWS. You then create virtual interfaces (VIFs) to segment the traffic to VPCs, public AWS services, or Transit Gateways.
Primary Components
- Customer Router — on-premises edge device running BGP.
- Partner / Telecom — if using a hosted connection.
- AWS Direct Connect Location — colocation where AWS co-locates DX routers.
- Virtual Interfaces (VIFs) — Private / Public / Transit.
- Direct Connect Gateway — enables sharing Direct Connect across multiple accounts and regions (except China).
4. Supported Connection Types (Dedicated vs Hosted)
Dedicated Connections
Dedicated connections are physical ports provisioned by AWS (1G, 10G, 100G). You receive full control and predictable performance.
Hosted Connections
Hosted connections are delivered by AWS Direct Connect Partners (telecoms) and are typically offered from 50 Mbps to 10 Gbps. Hosted VIFs allow multiple customers to share the same physical port.
- Choose dedicated when you need highest performance and non-shared ports.
- Choose hosted when speed/cost/turn-up time favor partner options.
- Hosted VIFs are ideal for smaller test/dev or when partner already has presence.
5. Virtual Interface (VIF) Options — Private, Public, Transit
VIFs are logical segmentation on a Direct Connect connection.
Private VIF
Used to access resources in your VPC using private IP addresses. Typical use: application servers, databases, storage replication.
Public VIF
Used to access AWS public services (S3, DynamoDB) using public IP addresses. Useful to avoid internet egress for S3 uploads.
Transit VIF
Transit VIF connects to a Direct Connect gateway for AWS Transit Gateway integration. Scales to connect thousands of VPCs across accounts and regions (regional caveats exist).
- Use separate VIFs to isolate traffic types (private vs public).
- Transit VIF + Transit Gateway is recommended for multi-VPC scale.
- VIFs can be provisioned in the Direct Connect console or via API/CLI.
6. Typical Architecture Scenarios
Hybrid Cloud (On-prem + VPC)
Private VIF to VPCs for application traffic; Public VIF for S3 access (uploads/downloads); Transit VIF for large multi-account networks.
Data Center Extension
Extend on-prem networks to AWS with BGP — treat VPCs as extended L3 networks. Use proper IP planning and route filters.
Disaster Recovery
Dedicated DR connectivity with Direct Connect for predictable RPO/RTO and fast replication.
- Transit VIF + TGW is a scalable pattern for multi-account/multi-VPC networks.
- Always plan IP addressing to avoid overlap between on-prem and VPCs.
7. Routing, BGP & Network Details
Direct Connect uses BGP for dynamic routing. Use multiple BGP sessions for redundancy and BGP community routing policies to control advertisements and route propagation.
BGP Example (sample peer config)
# Example: sample BGP settings (vendor agnostic)
local-as 65001
peer-as 7224
peer-ip 203.0.113.2
local-ip 203.0.113.1
hold-time 90
advertise only your on-prem prefixes (use route filters where needed)
Link Aggregation (LAG)
LAG aggregates multiple physical DX connections into a single logical interface for capacity scaling and simplified management. Configure identical settings on all LAG members.
- Enable BGP multipath where supported to load-balance across paths.
- Advertise only the necessary prefixes to AWS; use route filters/communities to avoid accidental leaks.
Troubleshooting BGP Flaps & Route Issues
- Confirm physical connectivity and cross-connect with colocation provider.
- Check BGP neighbor state (established / idle / active) on both ends.
- Review ASNs — local and peer ASN must match configured values.
- Verify prefix size limits and route filters on the Direct Connect console.
8. Security: MACsec, Encryption & Best Practices
MACsec provides Layer 2 link encryption for supported dedicated connections (primarily 10G and 100G). For end-to-end encryption, combine MACsec with IPsec (VPN) or application-level TLS where required.
Getting Started with MACsec
MACsec is enabled when creating a dedicated connection; you must configure the CAK/CKN on your router to match the Direct Connect configuration.
# Example (conceptual) — MACsec CAK/CKN
After provisioning, download the router configuration file from the Direct Connect console
Configure CAK (Connectivity Association Key) on on-prem router per vendor instructions
- MACsec encrypts the layer 2 link — protects traffic between you and AWS at the link hop.
- MACsec is not a replacement for end-to-end encryption; combine with TLS/IPsec if you need layered security.
9. High Availability & Resiliency Patterns
Design HA by deploying multiple DX connections at different Direct Connect locations and pairing them with Site-to-Site VPN fallback. Use BGP path selection and route priorities to prefer Direct Connect for performance and fail to VPN when needed.
Recommended Patterns
- Two DX connections in different DX locations (colos) — active/active or active/standby.
- Combine Direct Connect with VPN as a resilient backup.
- Use LAG for capacity and simplified failover across multiple members.
10. Monitoring & Observability
Use Amazon CloudWatch metrics for connection state, traffic in/out, and packet drops. Configure flow logs at the VPC level to observe patterns and identify large egress flows that might affect billing.
CloudWatch Metrics to Track
- Connection state (available / down)
- BytesIn/BytesOut
- Packet Drops
Sample CloudWatch CLI
# Get CloudWatch metric statistics for DX connection bytes out (example)
aws cloudwatch get-metric-statistics
--namespace "AWS/DX"
--metric-name "BytesOut"
--dimensions Name=ConnectionId,Value=dxcon-abc123
--start-time 2025-11-01T00:00:00Z --end-time 2025-11-02T00:00:00Z
--period 3600 --statistics Sum
- Set CloudWatch alarms for connection state changes and unusual throughput spikes.
- Use VPC flow logs and SIEM integration for deeper traffic analysis.
11. Billing & Pricing Considerations
Direct Connect pricing typically includes two main components: port-hour charges for the connection and data transfer out (DTO) charges. Pricing varies by region and port speed. Hosted connections through partners may have different pricing models.
- Port-hour charges are billed as part of the connection type (dedicated vs hosted).
- Data Transfer OUT is charged from AWS region to the Direct Connect location; Data Transfer IN is typically free.
- Using Direct Connect for heavy outbound traffic can save significant costs vs internet egress.
Tip: Review multi-account allocation and SiteLink features if connecting multiple accounts — these can affect billing distribution.
12. Hands-On: Provisioning & Troubleshooting Examples
Below are practical commands and examples to create and troubleshoot connections using AWS CLI and conceptual PowerShell-style steps (for teams that prefer PowerShell patterns). Always replace placeholders with your real values (connection IDs, virtual interface names, ASNs, IPs).
Create a Direct Connect connection (CLI)
# Request a dedicated connection
aws directconnect create-connection
--location EqSe1-AWS-DC
--bandwidth 10Gbps
--connection-name "Corp-DC-to-AWS-10G"
--lag-id ""Create a private virtual interface (CLI)
# Create a private VIF to connect to a VPC
aws directconnect create-private-virtual-interface
--connection-id dxcon-abc123
--new-private-virtual-interface file://private-vif.json
Example private-vif.json (minimal)
{
"virtualInterfaceName": "corp-private-vif",
"vlan": 101,
"asn": 65001,
"amazonAddress": "169.254.10.1/30",
"customerAddress": "169.254.10.2/30",
"virtualGatewayId": "vgw-0abcd1234"
}
PowerShell-style sample (Azure/AWS teams often use PowerShell wrappers)
# Pseudo-PowerShell (conceptual)
Install-Module AWSPowerShell.NetCore
Initialize-AWSDefaults -ProfileName default
Describe connections
Get-DXConnection -ConnectionId "dxcon-abc123"
Note: Use AWSPowerShell module commands to map to AWS CLI equivalents
Troubleshooting Checklist
- Confirm DX connection state in the Direct Connect console (available / ordering / provisioning / down).
- Verify cross-connect status with colocation partner.
- Confirm BGP neighbor is established (show ip bgp summary).
- Validate route advertisements & filters.
- Check CLoudWatch DX metrics for Packet Drops or unusual bytes patterns.
13. Real-World Use Cases
Common use cases include:
- Low-latency DB replication: synchronous/asynchronous backups between on-prem and RDS/EC2.
- High-volume media ingest: 4K/8K video upload pipelines.
- Financial trading systems: minimal jitter and deterministic latency.
- Cloud migration: bulk data migration with higher throughput and lower transfer time.
- Design endpoints and route policies based on whether traffic is internal (private VIF) or service-based (public VIF).
14. Comparison: Direct Connect vs VPN vs Azure ExpressRoute
Short comparison to help decide which connectivity option suits your needs.
| Feature | Direct Connect | Site-to-Site VPN |
|---|---|---|
| Latency | Very Low / Predictable | Higher / Variable |
| Bandwidth | Up to 100 Gbps | Usually <= 1.25 Gbps |
| Encryption | Optional MACsec | IPsec by default |
Direct Connect vs Azure ExpressRoute — both provide a dedicated line concept. Choice depends on cloud provider and service integration needs; ExpressRoute integrates natively with Azure services while Direct Connect integrates with AWS services and Transit Gateway.
15. Design Best Practices
- Deploy DX circuits in at least two different Direct Connect locations for redundancy.
- Use LAG to scale bandwidth and simplify management.
- Prefer Transit VIF + Transit Gateway (TGW) for multi-VPC architectures.
- Tag resources for billing and operational visibility.
- Implement CloudWatch alarms for DX connection state and throughput anomalies.
16. FAQ (Section-level) — Common Questions
Q: What port speeds are available?
A: Dedicated: 1 Gbps, 10 Gbps, 100 Gbps. Hosted: typically 50 Mbps–10 Gbps depending on partner.
Q: Is MACsec supported everywhere?
A: No — MACsec availability depends on the Direct Connect location and port speed. Verify on the Direct Connect console and AWS documentation.
Q: How do I connect multiple AWS accounts?
A: Use Direct Connect Gateway and Transit VIF to propagate connectivity to multiple accounts and Transit Gateways.
Leave a Reply