Network & Connectivity

ISP Peering Problem

ISP peering problems occur when the connection between two internet service providers is congested, broken, or non-existent. This can cause users on one ISP to experience slow or failed connections to services hosted on or transiting through another ISP, even though both endpoints are functioning correctly.

Symptoms

  • Users on specific ISPs cannot reach your server while others can
  • Consistently high latency from certain geographic regions
  • Traceroute showing high latency at specific ISP boundaries
  • Performance issues that only affect users of certain providers

Common Causes

  • Congested peering link between two ISPs
  • Depeering events removing direct connectivity
  • Traffic forced through distant transit paths instead of local peering
  • Peering capacity not scaled with traffic growth
  • Routing policy disputes between providers

Step-by-Step Troubleshooting

  1. 1

    Identify ISP path

    Run traceroute to see which ISPs are in the network path.

    Use Ping & Traceroute →
  2. 2

    Check ISP information

    Identify the ISP for the affected users.

    Use ISP Checker →
  3. 3

    Look up ASN details

    Check the ASN of both your provider and the affected ISP.

    Use ASN Lookup →
  4. 4

    Test from multiple locations

    Confirm the issue is ISP-specific by testing from different networks.

  5. 5

    Contact providers

    Report the peering issue to your hosting provider and/or CDN for possible route optimization.

Recommended Diagnostic Tools

Ping & TracerouteISP CheckerASN Lookup

Monitor Multi-Location Connectivity

Track connectivity from multiple locations to detect ISP-specific issues.

Related Problems

Frequently Asked Questions