I Would Like To Receive Feedback About My Network
I Would Like To Receive Feedback About My Network
Introduction
“I’d love to share my network diagram. Please give me feedback :)” - this Reddit plea resonates with every engineer who’s ever questioned their network design. In homelabs and production environments alike, network configuration remains one of the most consequential yet least visible aspects of infrastructure architecture.
When self-hosted services mysteriously disconnect, VPN tunnels fail to establish, or routing tables behave unexpectedly, the culprit often lies in fundamental network design choices. The Reddit comment highlighting subnet conflicts (“Avoid subnet 192.168.0.0 or 192.168.1.0”) exemplifies how seemingly minor decisions can create major operational headaches.
This guide examines professional network design principles through the lens of real-world peer feedback. You’ll learn:
- Why default IP ranges create conflict nightmares
- How to implement future-proof subnetting strategies
- VLAN segmentation techniques for security and performance
- Essential diagnostic tools every network engineer needs
- Documentation standards that enable effective peer review
Whether you’re configuring a homelab Kubernetes cluster or enterprise-grade infrastructure, these battle-tested practices will transform how you approach network architecture.
Understanding Network Design Fundamentals
The Hidden Costs of Default Configurations
The Reddit commenter’s warning about 192.168.0.0/24 and 192.168.1.0/24 subnets stems from RFC 1918’s designation of these ranges as:
| IP Range | Default Use Cases | Conflict Risk |
|---|---|---|
| 192.168.0.0/24 | Consumer routers, IoT devices | Extreme |
| 192.168.1.0/24 | Enterprise SOHO equipment | High |
| 192.168.100.0/24 | ISP modems, VPN concentrators | Moderate |
These conflicts manifest in two critical scenarios:
- VPN Tunnel Collisions: When connecting to a remote network that uses identical IP ranges
- Device Provisioning Failures: When factory-default devices clash with existing addresses
Subnetting Strategies for Scalability
Instead of default ranges, consider these RFC 1918-compliant alternatives:
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# High-density networks
10.42.0.0/16 -> 10.42.0.0/24 (User VLAN)
-> 10.42.1.0/24 (Server VLAN)
-> 10.42.2.0/24 (IoT VLAN)
# Medium networks
172.21.32.0/20 -> 172.21.32.0/24 (Core Services)
-> 172.21.33.0/24 (DMZ)
The Diagram Imperative
Network diagrams serve three critical functions:
- Troubleshooting Acceleration: Visualize traffic flow during outages
- Security Auditing: Identify unintended exposure points
- Capacity Planning: Map device density to broadcast domains
Top tools for network visualization:
- Diagram-as-Code: Diagrams.net (formerly draw.io) VSCode extension
- Automated Discovery: NetBox IPAM with Graphviz export
- Professional Suites: Lucidchart, Microsoft Visio
Prerequisites for Professional Networking
Hardware Requirements
| Device Type | Homelab Specification | Production Specification |
|---|---|---|
| Router | x86 w/ AES-NI (pfSense/OPNsense) | ASIC-based (Cisco ASR, Juniper MX) |
| Switch | Managed L2 (VLAN support) | L3 with 10G uplinks |
| Firewall | Integrated in router | Dedicated appliance (Palo Alto, Fortinet) |
Software Tooling
Essential network utilities:
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# Debian-based install
sudo apt install -y \
nmap \ # Network discovery
tcpdump \ # Packet analysis
iperf3 \ # Bandwidth testing
net-tools \ # Legacy utilities (ifconfig)
iproute2 \ # Modern ip commands
wireguard \ # VPN implementation
bridge-utils # Linux bridging
Security Considerations
- Airgap Critical Networks: Isolate SCADA/IoT devices from management interfaces
- Implement RFC 4193: Use ULAs (fc00::/7) for IPv6 internal networks
- Certificate Authority: Deploy private PKI for device authentication
Network Implementation Guide
VLAN Configuration Example
pfSense VLAN setup (/etc/config.xml):
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<vlans>
<vlan>
<if>em1</if>
<tag>42</tag>
<vlanif>vlan42</vlanif>
<descr>SERVER_VLAN</descr>
</vlan>
</vlans>
Corresponding Linux bridge (/etc/netplan/01-bridges.yaml):
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network:
version: 2
bridges:
br-vlan42:
interfaces: [enp3s0.42]
addresses: [10.42.1.1/24]
mtu: 9000
parameters:
stp: true
BGP Edge Router Configuration
FRRouting (/etc/frr/frr.conf):
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router bgp 65101
bgp router-id 10.42.0.1
neighbor 203.0.113.5 remote-as 64496
!
address-family ipv4 unicast
network 10.42.0.0/16
neighbor 203.0.113.5 activate
exit-address-family
WireGuard VPN Implementation
wg0.conf server configuration:
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[Interface]
Address = 10.99.0.1/24
PrivateKey = server_private_key
ListenPort = 51820
# Client configuration
[Peer]
PublicKey = client_public_key
AllowedIPs = 10.99.0.2/32
Configuration Best Practices
IP Address Management (IPAM)
NetBox inventory structure:
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prefixes:
- prefix: 10.42.0.0/16
site: Primary DC
vlan: 42
status: active
description: Core infrastructure
ip_addresses:
- address: 10.42.1.1/24
device: core-switch-01
interface: Vlan42
role: anycast-gateway
Firewall Rule Methodology
OPNsense rule hierarchy:
- Anti-Lockout Rule: Allow management access from trusted networks
- Default Deny: Block all inbound traffic by default
- Explicit Allows: Service-specific rules with logging
- IoT Isolation: Block IoT → LAN traffic except DNS/NTP
Routing Table Optimization
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# Linux policy routing example
ip route add default via 203.0.113.1 table 100
ip rule add from 10.42.2.0/24 lookup 100
Operational Maintenance
Network Monitoring Stack
Prometheus SNMP exporter configuration:
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modules:
if_mib:
walk:
- 1.3.6.1.2.1.2 # interfaces
- 1.3.6.1.2.1.31.1.1 # ifXTable
metrics:
- name: ifInDiscards
oid: 1.3.6.1.2.1.2.2.1.13
type: gauge
Backup Strategy
RANCID configuration for network device backups:
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# /etc/rancid/rancid.conf
LIST_OF_GROUPS="core-switches edge-routers"
BASEDIR="/var/lib/rancid"
LOGDIR="$BASEDIR/logs"
Capacity Planning Metrics
Critical thresholds to monitor:
| Metric | Warning | Critical | Collection Method |
|---|---|---|---|
| ARP table utilization | 70% | 90% | SNMP ifTable |
| BGP session flaps | 5/hr | 20/hr | Prometheus |
| Broadcast traffic | 10% | 25% | sFlow sampling |
Troubleshooting Methodology
Layer-by-Layer Diagnostics
- Physical Layer:
ethtool enp3s0 - Data Link:
bridge fdb show - Network:
mtr --report-wide 8.8.8.8 - Transport:
ss -tulpn - Application:
journalctl -u nginx
Packet Capture Techniques
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# Capture DNS traffic on VLAN42
tcpdump -ni vlan42 -s0 port 53 -w dns_capture.pcap
# Analyze HTTP requests
tshark -r capture.pcap -Y 'http.request' -T fields \
-e frame.time -e ip.src -e http.host -e http.request.uri
BGP Failure Scenarios
Common issues and diagnostics:
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# Check session state
vtysh -c "show bgp summary"
# Examine route advertisements
bgpdump -m /var/log/frr/bgp.pcap
Conclusion
Constructing enterprise-grade networks requires moving beyond default configurations and convenience subnets. By implementing deliberate IP allocation strategies, enforcing strict VLAN segmentation, and maintaining comprehensive documentation, you create networks that withstand both technical scrutiny and real-world demands.
For further study:
- RFC 1918: Address Allocation for Private Internets
- NIST SP 800-125B: Secure Virtual Network Configuration
- Cisco Enterprise Network Design Model
The next frontier? Automating network validation with tools like Batfish for pre-deployment analysis. Remember - in networking, simplicity emerges from rigorous design, not default configurations.