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Tunnel Connectivity

This guide explains how to verify and maintain connectivity for your USDN tunnels, ensuring optimal performance and reliability.

Connectivity Overview​

Connection Types​

  1. Point-to-Point
  2. Point-to-Multipoint
  3. Mesh Network
  4. Custom Configurations

Connection States​

  • Initializing
  • Connected
  • Degraded
  • Disconnected
  • Maintenance

Verifying Connectivity​

Basic Connectivity Tests​

  1. Ping test:

    ping remote-endpoint

  2. Traceroute:

    traceroute remote-endpoint

  3. MTU verification. The MTU is the largest packet a link can carry without splitting it up. USDN tunnels encrypt and encapsulate your traffic, so a packet crossing a tunnel must be smaller than on a plain 1500-byte Ethernet link. The exact limit depends on the tunnel type and is set by the platform, and you don't need to know it: send one probe that fits every USDN tunnel and one that fits none, both with "don't fragment" set (-s is the payload; the IPv4 and ICMP headers add 28 bytes):

    ping -M do -c 3 -s 1300 <remote-lan-ip>   # fits every USDN tunnel: expect replies
    ping -M do -c 3 -s 1400 <remote-lan-ip>   # fits none: expect "Frag needed"

    On macOS use ping -D -s <size>; on Windows, ping -f -l <size>.

    The first probe should get replies. The second should be refused at once with Frag needed and DF set (mtu = ...), naming the path's limit, for example mtu = 1370 or mtu = 1392 (Linux then reports message too long for the remaining packets). That refusal is path-MTU discovery working: your applications learn the limit and size their packets to fit. If the second probe only times out, with no "Frag needed" message, something on the path is dropping the ICMP "fragmentation needed" messages that path-MTU discovery relies on: check firewalls and NAT devices between the host and the tunnel. If the first probe fails while a plain ping works, contact support with both outputs.

Advanced Testing​

  1. Bandwidth testing:

    iperf -c remote-endpoint

  2. Latency testing:

    mtr remote-endpoint

  3. Connection stability:

    ping -f remote-endpoint

Performance Verification​

Bandwidth Tests​

  1. Download speed test
  2. Upload speed test
  3. Throughput verification
  4. Capacity testing

Quality Metrics​

  1. Latency measurement
  2. Packet loss tracking
  3. Jitter analysis
  4. Connection stability

Troubleshooting Tools​

Built-in Tools​

  1. Connection monitor
  2. Performance graphs
  3. Error logs
  4. Diagnostic tools

External Tools​

  1. Network analyzers
  2. Protocol analyzers
  3. Packet capture
  4. Traffic generators

Common Issues​

Connection Problems​

  1. Authentication failures
  2. Configuration errors
  3. Network issues
  4. Hardware problems

Performance Issues​

  1. Bandwidth constraints
  2. High latency
  3. Packet loss
  4. MTU mismatches

Maintenance​

Regular Checks​

  1. Connection status
  2. Performance metrics
  3. Error rates
  4. Configuration validation

Preventive Maintenance​

  1. Configuration backups
  2. Software updates
  3. Security patches
  4. Performance optimization

Monitoring​

Real-time Monitoring​

  1. Connection status
  2. Performance metrics
  3. Error rates
  4. Security events

Historical Analysis​

  1. Performance trends
  2. Usage patterns
  3. Capacity planning
  4. Optimization opportunities

Security Verification​

Security Checks​

  1. Encryption status
  2. Authentication logs
  3. Access controls
  4. Security policies

Compliance​

  1. Security standards
  2. Audit requirements
  3. Policy compliance
  4. Documentation

Best Practices​

Connection Management​

  1. Regular testing
  2. Performance monitoring
  3. Documentation
  4. Change control

Security​

  1. Regular audits
  2. Access reviews
  3. Policy updates
  4. Security training

Need Help?​

If you need assistance with tunnel connectivity:

  1. Review our Support and Escalation Levels to understand available support options
  2. Check our troubleshooting guide
  3. Contact support through the Support Portal
  4. Schedule a consultation with our Professional Services team