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howto:connectivity-monitor

Connectivity Monitor

The connectivity monitor runs every minute and measures and logs the WAN interface performance using ICMP echo probes.

Browse to Network → Network Configuration and edit your WAN interface. Tick Enable connectivity test and choose your target IP address. We recommend using ISP DNS servers. Timeout is in seconds, combined with the amount of retries equals the downtime before a link is declared dead.

Traffic from the connectivity monitor follows the interface route table (view your route table) towards it's destination. If you are not using multiple WAN interfaces, browse to Network > Network configuration > Overview and review the Default route table.

Otherwise browse to Network > Load-Balancing and make a note of the id in the right corner of each WAN-balanced interface. Then browse to Network > Network configuration > Overview and find the matching table using the ID (table1 = id 1).

It's possible to steer the traffic into a specific direction using static routes (the most specific route matches). eg. Your WAN interface 172.20.0.33/24 has gateway 172.20.0.1. Your connectivity monitor tests for 4.2.2.1 (Level 3 Networks Public DNS server). By default traffic will be sent out towards 172.20.0.1, to manipulate we add a route to 4.2.2.1/29 over WAN via 172.20.0.2.

Notes

  • You can force traffic over a specific interface using static routes.
  • You can manipulate traffic over a different gateway using static routes.
  • If you configure different testing targets per interface it becomes easier to debug with packet captures (eg. upstream gateway sends replies back to wrong interface).
howto/connectivity-monitor.txt · Last modified: 2015/07/23 10:09 by ewald