VPC Reachability Analyzer is a powerful diagnostic tool within AWS that helps administrators troubleshoot network connectivity issues between resources in their Virtual Private Cloud (VPC). This configuration analysis tool determines whether a destination resource is reachable from a source resourc…VPC Reachability Analyzer is a powerful diagnostic tool within AWS that helps administrators troubleshoot network connectivity issues between resources in their Virtual Private Cloud (VPC). This configuration analysis tool determines whether a destination resource is reachable from a source resource within your VPC infrastructure.
The analyzer works by examining the network configuration rather than sending actual packets through the network. It evaluates all relevant networking components including security groups, network ACLs, route tables, VPC peering connections, transit gateways, VPC endpoints, and internet gateways to determine if traffic can flow between specified endpoints.
Key features include:
1. **Path Analysis**: Creates a virtual path between source and destination, identifying each hop and potential blocking components along the route.
2. **Supported Resources**: Works with EC2 instances, network interfaces, internet gateways, VPC endpoints, VPC peering connections, and transit gateway attachments.
3. **Reachability Insights**: Provides detailed explanations when connectivity fails, pinpointing exactly which configuration element is blocking traffic.
4. **Protocol Support**: Analyzes TCP and UDP traffic patterns based on port configurations.
For SysOps Administrators, this tool is invaluable for several scenarios:
- Verifying security group rules allow intended traffic
- Confirming route table entries are correctly configured
- Validating network ACL rules permit communication
- Troubleshooting connectivity issues between EC2 instances
- Auditing network configurations for compliance
The analyzer generates reachability paths that display successful configurations or identify problematic components. Results are stored and can be referenced for documentation or audit purposes.
Pricing is based on the number of analyses performed, making it cost-effective for periodic troubleshooting. This tool significantly reduces the time spent manually reviewing multiple networking components and eliminates guesswork when diagnosing connectivity problems in complex VPC architectures.
VPC Reachability Analyzer - Complete Guide
Why is VPC Reachability Analyzer Important?
VPC Reachability Analyzer is a critical tool for AWS SysOps Administrators because it eliminates the need for manual troubleshooting of network connectivity issues. Instead of sending actual traffic and analyzing packet captures, you can perform configuration analysis to identify connectivity problems before they impact your applications. This saves significant time during incident response and helps maintain operational excellence.
What is VPC Reachability Analyzer?
VPC Reachability Analyzer is a network diagnostics tool that enables you to perform connectivity testing between resources in your Amazon VPCs. It analyzes the virtual network configuration to determine whether a destination is reachable from a source. The tool examines all network components in the path including:
- VPCs and VPC Peering connections - Internet Gateways and NAT Gateways - Virtual Private Gateways - Transit Gateways - VPC Endpoints - Network interfaces (ENIs) - Security Groups - Network ACLs - Route Tables
How Does VPC Reachability Analyzer Work?
1. Create an Analysis Path: You define a source and destination, which can be EC2 instances, ENIs, Internet Gateways, VPN Gateways, Transit Gateways, or VPC Endpoints.
2. Specify Protocol Details: You can optionally specify the protocol (TCP/UDP), source port, and destination port to narrow down the analysis.
3. Run the Analysis: The Reachability Analyzer examines the configuration of all components between the source and destination. No actual packets are sent - this is purely a configuration-based analysis.
4. Review Results: If the path is reachable, you see the complete hop-by-hop path. If unreachable, the tool identifies the blocking component such as a misconfigured security group rule, missing route, or restrictive NACL.
5. Pricing: You are charged per analysis run. Each analysis has a cost regardless of whether the path is reachable or not.
Key Features to Remember:
- Does not send actual network traffic - Analyzes configuration only - Identifies the specific component causing connectivity failure - Supports both IPv4 and IPv6 - Works across VPC peering and Transit Gateway connections - Results are stored and can be compared over time
Exam Tips: Answering Questions on VPC Reachability Analyzer
1. Configuration vs Traffic Analysis: When exam questions mention troubleshooting connectivity problems by analyzing network configuration rather than sending test traffic, VPC Reachability Analyzer is the answer.
2. Identifying Blocking Components: If a question asks about finding which security group, NACL, or route table is blocking traffic, think Reachability Analyzer.
3. No Packet Sending: Remember that this tool does NOT send packets. If the question mentions analyzing actual traffic flow, consider VPC Flow Logs instead.
4. Cross-VPC Analysis: The tool works across VPC peering and Transit Gateway connections - this is a common exam scenario.
5. Cost Awareness: Be aware that each analysis incurs a charge. Questions about cost-effective troubleshooting may factor this in.
6. Common Distractors: Do not confuse with: - VPC Flow Logs - captures actual traffic metadata - Traffic Mirroring - copies actual packet data - Network Access Analyzer - analyzes unintended network access