Here are frequent BGP issues and how to diagnose them.
Session won't establish:
- Check TCP connectivity (port )
- Verify ASN matches
- Confirm passwords match
- Check firewall
Routes not received:
- Is session established?
- Filtered by peer?
- Inbound filter on your side?
Routes not advertised:
- Is route in your BGP table?
- Outbound filter blocking it?
- Valid NEXT_HOP?
Suboptimal paths:
- Check LOCAL_PREF
- Examine AS_PATH lengths
- Look for unexpected prepending