Route Optimization

Pathvector can use latency and packet loss metrics to make routing decisions. The optimizer works by sending ICMP or UDP ping out different peer networks and modifying BGP local pref according to average latency and packet loss thresholds.

How it works

1. Run pathvector generate first. The optimizer works on the active BIRD configuration in the bird-directory (/etc/bird/ by default) that generate writes.
2. Start the optimizer with pathvector optimizer. It probes the global optimizer.targets from each peer's probe-sources every probe-interval seconds and keeps the last cache-size results per peer.
3. When a peer's average latency or packet loss meets or exceeds latency-threshold or packet-loss-threshold, the optimizer runs the alert script (if configured) and, for peers with optimize-inbound: true, lowers the peer's local pref to local-pref - modifier by editing the peer's config file in the BIRD directory in place. The modified config is validated with BIRD and BIRD is reconfigured (unless --no-configure is set). The depref is applied once per alerting period; when the peer's metrics drop back below the thresholds, the optimizer restores the configured local pref the same way.

With --dry-run, the optimizer logs the local pref change it would make without modifying any files.

The next pathvector generate run restores the configured local pref.

optimizer:
  targets: [ "192.0.2.53" ]
  latency-threshold: 100 # ms
  packet-loss-threshold: 0.5 # percent
  modifier: 20

peers:
  Transit:
    asn: 64496
    local-pref: 100
    neighbors:
      - 203.0.113.1
    probe-sources: [ "203.0.113.2" ]
    optimize-inbound: true

Alert Scripts

To be notified of an optimization event, you can add a custom alert script that Pathvector will call when the latency or packet loss meet or exceed the configured thresholds.