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BIRD Configuration Guide

Overview

The MoeNet Agent automatically generates and maintains BIRD 3.x configuration files for DN42 routing. This includes filters, communities, Babel IGP, and cold potato routing.

Generated Configuration Files

File Purpose
filters.conf DN42 import/export filters, prefix validation
moenet_communities.conf MoeNet Large Community definitions for cold potato
babel.conf Babel IGP configuration for mesh connectivity
cold_potato.conf Cold potato routing functions
ibgp.d/*.conf iBGP peer configurations
peers/*.conf External BGP peer configurations

DN42 Communities

The agent sets DN42 standard communities (64511, xx) only on self-originated routes:

Community Value Purpose
Region (64511, 41-53) Geographic region
Bandwidth (64511, 21-25) Link capacity
Latency (64511, 1-9) RTT tier
Crypto (64511, 31-34) Encryption status

Important: Export Filter Behavior

The export filter distinguishes between route sources:

filter dn42_export_filter {
    # Self-originated routes: add our communities
    if (source = RTS_STATIC || source = RTS_DEVICE) then {
        add_self_origin_communities();  # Only here!
        accept;
    }
    
    # BGP-learned routes: pass through unchanged
    if (source = RTS_BGP) then {
        accept;  # No community modification
    }
    
    reject;
}

Warning: Never add region/country communities to foreign prefixes. This can cause routing anomalies for other networks.

MoeNet Large Communities

Internal communities for cold potato routing within MoeNet backbone:

Type Format Purpose
Origin Continent (4242420998, 1, xx) AS, NA, EU, OC, Other
Origin Subregion (4242420998, 2, xxx) AS-E, AS-SE, EU-W, etc
Origin Node (4242420998, 3, nodeId) Specific node ID
Link Characteristics (4242420998, 4, x) Intercontinental, high-lat
Bandwidth (4242420998, 5, mbps) Granular bandwidth

Cold Potato Routing

Cold potato routing keeps traffic inside the MoeNet backbone as long as possible:

  1. Same subregion: +100 local_pref
  2. Same continent: +50 local_pref
  3. Adjacent continent (AS↔OC, NA↔EU): -50 local_pref
  4. Remote continent: -200 local_pref

Region Codes

Code Region DN42 Community MoeNet LC
101 East Asia (64511, 50) LC_REGION_AS_E
102 Southeast Asia (64511, 49) LC_REGION_AS_SE
103 South Asia (64511, 48) LC_REGION_AS_S
201 NA East (64511, 42) LC_REGION_NA_E
202 NA Central (64511, 43) LC_REGION_NA_C
203 NA West (64511, 44) LC_REGION_NA_W
301 EU West (64511, 41) LC_REGION_EU_W
302 EU Central (64511, 41) LC_REGION_EU_C
401 Oceania (64511, 51) LC_REGION_OC

Babel IGP

Babel is used for IGP mesh connectivity between MoeNet nodes:

  • Interface pattern: dn42-wg-igp-*
  • Type: tunnel (for WireGuard P2P links)
  • RTT cost enabled for path selection
  • Only propagates loopback addresses (/32, /128)

Configuration Sync

The birdConfigSync task runs every 300s and:

  1. Fetches configuration from Control Plane API
  2. Compares config hash for changes
  3. Renders templates if changed
  4. Reloads BIRD (birdc configure)

Troubleshooting

Check generated configs

cat /etc/bird/filters.conf
cat /etc/bird/moenet_communities.conf
cat /etc/bird/babel.conf
cat /etc/bird/cold_potato.conf

Verify communities on routes

birdc show route for 172.23.0.0/24 all

Check export filter

birdc show route export dn42_peer_xxx