FAQ

Frequently Asked Questions

Getting Help

Where can I ask for help?

• GitHub Issues — bug reports and feature requests
• Slack Community — real-time chat
• Google Group — mailing list (exabgp-users@googlegroups.com)

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General

What is ExaBGP?

ExaBGP is a pure BGP protocol implementation. It does NOT manipulate the kernel routing table (RIB/FIB). It speaks BGP to routers and provides a simple API for your programs to control route announcements.

Is this code supported?

Yes. Report bugs on GitHub and they will be fixed.

What platforms are supported?

• Linux: Primary deployment target
• macOS: Fully supported (development platform)
• FreeBSD/OpenBSD: Supported
• Windows: Should work, but not actively tested

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Connection Issues

ExaBGP does not listen for incoming connections

ExaBGP does not listen for incoming connections by default. You must specify the IP to listen to:

env exabgp.tcp.bind="127.0.0.1" exabgp.tcp.port=1790 exabgp config.conf

"could not connect to peer: timed out"

Check these in order:

1. Network connectivity — can your machine reach the router? (firewall, routing)
2. MD5 passwords — must match on both sides
3. Multihop — you may need outgoing-ttl for non-directly connected peers
4. FreeBSD users — check /etc/ipsec.conf has the correct password

"The client took over N seconds to send the OPEN, closing"

BGP Connection Collision Detection issue. Either:

• Set ExaBGP's router-id higher than the peer's router-id, or
• Configure your router for passive mode:
  • Cisco: neighbor X.X.X.X transport connection-mode passive
  • Juniper: set protocols bgp group <group> neighbor <address> passive

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FRRouting / Quagga

FRRouting rejects the connection

ExaBGP rejects BGP OPEN messages with router-id 0.0.0.0 per RFC 6286. This is FRRouting's default. Fix:

router bgp 65000
  bgp router-id 192.168.1.1

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IPv6

IPv6 routes cause the session to drop

Enable the IPv6 address family on your router:

# Juniper
set protocol bgp group mygroup neighbor <IP> family inet6 unicast
set protocol bgp group mygroup neighbor <IP> family inet unicast

If sending both IPv4 and IPv6 routes, you must explicitly enable both families.

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Route Issues

Routes are not installed on the router

You may need to allow non-directly-connected next-hops:

# Juniper
set protocol bgp group mygroup neighbor <IP> accept-remote-nexthop

Does ExaBGP prepend the local AS to the AS-PATH?

• eBGP: Yes, the local ASN is prepended automatically (prevents loops)
• iBGP: The AS-PATH is sent as configured

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Configuration

How do I reload the configuration?

Send SIGUSR1:

kill -USR1 $(pidof exabgp)

ExaBGP compares the old and new configurations, tears down removed peers, sets up new ones, and announces/withdraws changed routes.

What is the split feature?

route 10.0.0.0/16 next-hop 1.2.3.4 split /24;

This announces 256 individual /24 routes that make up the /16. Useful when you need more specific routes to override less specific ones.

Can I save the PID for scripts?

env exabgp.daemon.pid="/var/run/exabgp.pid" exabgp config.conf

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Protocol

Juniper rejects hold-time below 20 seconds

Juniper requires hold-time >= 6 seconds (hidden command to lower it):

set minimum-hold-time 6

Why does ExaBGP support Graceful Restart?

For services announcing IPs without backup: during reboots, the service IP remains routed. Set graceful-restart to a value higher than your reboot time (default 180s is often too low for servers).

Can ExaBGP work behind NAT?

Yes. Set local-address to your LAN IP and router-id to the NAT's public IP.

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TCP MD5

"This OS does not support TCP_MD5SIG"

macOS does not support TCP MD5 signatures. Use a different OS if you need MD5 authentication.

FreeBSD MD5 setup

FreeBSD requires MD5 keys to be configured via /etc/ipsec.conf. Add md5 kernel; to your ExaBGP config and follow the FreeBSD documentation.

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Performance

How many peers can one instance handle?

Depends on route volume, but under normal use (even thousands of routes) a single instance works fine. Deployments with 160+ peers (low route volume) and single-peer with 20+ updates/second have been reported.

ExaBGP uses select() for non-blocking I/O. If concerned, run one instance per peer.

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See Also

• Common Pitfalls — avoid frequent mistakes
• Debugging — troubleshooting guide
• API Overview — API documentation