Recommending Metrics for Network Status Visibility

Bit the Chipmunk, AWS Expert published on
5 min, 877 words

Hey there, network watchers! Bit here, perched high in the branches of your cloud infrastructure. Today we’re going to dig into the “what to monitor” part—meaning which metrics you should pick so you can keep your network healthy, performant and ready for global/hybrid scale. If you’re prepping for the AWS Advanced Networking exam, this is one of the nuts you’ve got to crack.

🧭 1. Why Metric Selection Matters

Turning on logs or metrics willy-nilly doesn’t help much. What your architecture design needs is a set of meaningful metrics that answer questions like:

  • Is this link healthy or degrading?
  • Are we hitting capacity limits or bottlenecks?
  • When did latency or packet losses spike—and where?
  • Are the hybrid (on-prem ↔ AWS) paths performing within baseline?
  • Are configuration changes or route-table updates impacting network health?

Selecting metrics is about visibility: giving your network team, your global architecture, and the exam grader proof that you know what to watch—and why.

📈 2. Core Network Metrics You Should Recommend

a) Traffic & Throughput Metrics

  • BytesIn / BytesOut (for AWS Transit Gateway attachments) — see volume of traffic flowing.
  • PacketsIn / PacketsOut — count of packets. Helps when packet size changes but volume stays relatively constant.
  • BytesDropped or PacketsDropped — especially for “no route” or “black-hole” drops in TGW.

Why monitor: High throughput might be fine—but if drops or blackholes are increasing, you’ve got a hidden issue.

b) Latency & Loss Metrics

  • Round Trip Time (RTT) and Packet Loss Percentages — for hybrid links or VPC-to-on-prem, using Amazon CloudWatch Network Monitor or similar.
  • Client Response Time, Target Processing Time, Request Processing Time — for load balancers (from access logs and CloudWatch).
  • Network Performance Metrics on EC2 (ENA driver) — e.g., when PPS (packages per second) limits are exceeded.

Why monitor: Latency and loss directly impact user experience. On the exam, a scenario might ask about degraded performance even though “traffic volume looks normal.”

c) Health & Availability Metrics

  • Status and State Metrics for attachments/tunnels/gateways (VPN tunnel UP/DOWN, TGW attachment status) via CloudWatch and TGW Network Manager.
  • Utilization Metrics for interfaces or attachments nearing quota or capacity (TGW per-AZ quotas).
  • Baseline Deviation Alerts – monitor deviation from historical baseline, not just absolute thresholds.
  • Route 53 Resolver Metrics — for hybrid networks using Route 53 Resolver Endpoints, track DNSQueries and HealthCheckStatus to detect DNS failures or endpoint unavailability.

Why monitor: It’s not just “is the link up?” but “is the link healthy and performing as expected?”

d) Hybrid Connectivity & Multi-Region Metrics

  • Per-AZ metrics (for TGW) – differentiate traffic across Availability Zones.
  • Inter-Region Transit Metrics – bytes transferred between regions and attachments in multiple accounts.
  • Direct Connect Link Metrics – traffic, error rates, link flaps, and connection health over time.

Why monitor: Global architectures must handle failover, cross-region performance, and multi-account visibility. The exam will test your awareness of those dimensions.

🧩 3. How to Recommend These in a Design Scenario

When you are asked to design monitoring for a network (especially hybrid/multi-region), follow this flow:

  1. Define SLAs / KPIs: e.g., “Global latency < 150 ms”, “Packet loss < 0.1%”, “No black-hole drops.”

  2. Map each KPI → metric(s):

    • Latency → RTT / client_response_time
    • Availability → Tunnel status / attachment status
    • Throughput → BytesIn + BytesOut
    • Drops → PacketsDropped or BytesDropped

  3. Select & configure sources: CloudWatch Metrics, Network Monitor, TGW Metrics, EC2 ENA metrics.

  4. Define alarm thresholds & dashboards: e.g., average client_response_time > 200 ms for 5 minutes triggers an alarm.

  5. Ensure global/central visibility: across accounts and regions—use CloudWatch Metric Streams to send metrics to S3 or Kinesis Firehose, or deploy the CloudWatch Agent on hybrid hosts for custom metrics.

  6. Document baseline and trend strategy: measure initial baseline, monitor deviation over time.

✅ 4. Best Practices & Exam-Traps

Best Practices:

  • Pick meaningful metrics, not all metrics. Focus on high-value ones (throughput, latency, drops, health).
  • Maintain a baseline and monitor deviations rather than static thresholds.
  • Use per-AZ / per-region breakdowns for global performance visibility.
  • Centralize metrics using CloudWatch Metric Streams, cross-account dashboards, or Kinesis Firehose for hybrid/multi-region architectures.

Exam Traps:

  • Choosing irrelevant metrics (e.g., CPUUtilization for a network-only SLA question).
  • Ignoring packet drops or black-hole metrics (BytesDropped due to no route).
  • Failing to monitor hybrid links or cross-region traffic when the architecture clearly includes them.
  • Forgetting latency/loss metrics for user experience—throughput alone isn’t enough.

📚 Further Reading

🐿️ Bit’s Final Nut

Metrics are like the heartbeat and vitals of your network. If you pick the right ones, you’ll see problems before users do, understand what’s happening, and answer the exam scenario with confidence. Keep your metrics sharp, your dashboards ready, and your network healthy. Stay metric-wise and stay clever! 🌰