Task Statement 3.1: Maintain routing and connectivity on AWS and hybrid networks.
📘AWS Certified Advanced Networking – Specialty
AWS networking services, like VPCs, Direct Connect, Transit Gateways, and others, have limits and quotas. These are rules that define how much you can use a service, how many resources you can create, or the capacity of the service.
Why it matters for exams:
- AWS imposes limits to ensure performance, stability, and security.
- Knowing these limits helps you design networks that work efficiently and avoid failures.
- Some limits can be soft limits (you can request an increase), and some are hard limits (cannot be increased).
1. Bandwidth Limits
Bandwidth is the amount of data that can travel over a network in a specific time. AWS networking services have limits on bandwidth, which affects data transfer speed.
Key Points:
- VPC Peering:
- There is a limit on the maximum bandwidth between two VPCs.
- Example: A VPC peering connection might support up to 10 Gbps between EC2 instances in different VPCs.
- Direct Connect:
- Each Direct Connect connection has a maximum port speed, like 1 Gbps, 10 Gbps, or 100 Gbps.
- Impact: If your applications need 15 Gbps, a 10 Gbps Direct Connect will bottleneck traffic.
- VPN Connections:
- AWS-managed VPNs typically support up to 1.25 Gbps per tunnel, so high-volume traffic may need multiple tunnels or a Direct Connect instead.
Exam Tip: You might be asked which service to choose based on traffic needs. Bandwidth limits help decide whether VPN or Direct Connect is suitable.
2. Route Limits
Routing in AWS defines how network traffic is directed between networks (VPCs, on-premises, etc.). AWS has limits on the number of routes you can configure.
Key Points:
- VPC Route Tables:
- Each route table can have up to 50 routes by default.
- Example: If you have 30 subnets and 25 peered VPCs, you may hit this limit.
- Transit Gateway (TGW) Routes:
- Transit Gateway route tables have limits (e.g., 10,000 routes per TGW route table).
- Exceeding this limit means some networks cannot be reached until you adjust routing or split route tables.
- Direct Connect Gateway (DXGW):
- There are limits on the number of prefixes (routes) advertised to AWS or on-premises.
- Example: Default limit is 1,000 routes; if your network grows beyond that, you need to request a quota increase.
Exam Tip: Questions often involve designing hybrid networks. Knowing route limits helps you avoid exceeding maximum routes, which can break connectivity.
3. Connection and Resource Limits
AWS networking services also have limits on connections or resources, which affects scalability:
| Service | Limit Example | Exam-Relevant Note |
|---|---|---|
| VPC Peering | Max 125 active connections per VPC | You can request an increase if needed |
| VPN | Max 10 VPN connections per VGW | Consider if connecting multiple branch offices |
| Direct Connect | Max 50 virtual interfaces per connection | Important for multi-VPC connectivity |
| Transit Gateway | Max 5,000 attachments per TGW | Large enterprises must plan for limits |
| ENI (Elastic Network Interface) | Max ENIs per EC2 instance | Choose instance type carefully for multi-NIC applications |
4. Soft vs Hard Limits
- Soft limits: Can be increased by requesting AWS Support.
- Example: Number of routes in a Transit Gateway.
- Hard limits: Cannot be increased.
- Example: Maximum bandwidth of a single VPN tunnel (1.25 Gbps).
Exam Tip: Questions may ask how to handle “limit reached” situations. Knowing which limits are adjustable is key.
5. Why Limits and Quotas Matter in IT Networks
- Limits affect scalability. Exceeding limits can prevent adding new VPCs, routes, or connections.
- Limits affect availability. Bandwidth limits can cause slow applications.
- Limits affect cost planning. Choosing the right type of connection avoids overpaying for unused capacity.
Example Scenario:
You have multiple offices connecting to AWS through a Transit Gateway. If the number of route prefixes exceeds the TGW route limit, some offices won’t reach certain VPCs until you either split route tables or request a quota increase.
6. How to Monitor and Manage Limits
- AWS Service Quotas Console: Check current limits and usage.
- CloudWatch Metrics: Monitor traffic and connections to identify bottlenecks.
- Automation: Use IaC (Terraform, CloudFormation) to track configurations and avoid exceeding limits.
✅ Exam Checklist
Remember for the exam:
- Know bandwidth limits for VPN, Direct Connect, and VPC Peering.
- Know route limits for VPC, TGW, and DXGW.
- Know connection/resource limits (ENIs, VPN, TGW attachments).
- Distinguish between soft and hard limits.
- Understand impacts on network design: scaling, availability, and hybrid connectivity.
- Know how to request quota increases when necessary.
By understanding these points, you can design AWS networks that scale efficiently and comply with AWS limits, which is exactly what the exam tests.
