NAME

exabgp — Influence or control network using BGP

SYNOPSIS

DESCRIPTION

exabgp allows engineers to control their network from commodity servers. Possible uses include DDoS mitigation, network visualisation, service high availability and implementing anycast. exabgp does not perform any FIB manipulation on the system it runs on; if you need that this is not the program for you. exabgp can also print received BGP messages into readable plain text or JSON formatted text.

The arguments are as follows:

--help | -h: Display summary of usage and configuration of exabgp.
--version | -v: Display the exabgp version number and exit.
--root folder | -f folder: Root folder where etc, bin, sbin are located.
--env env-config | -e env-config: Specify where the environment configuration file can be found.
--full-ini | --fi: Display the full environment configuration using on stdout using the ini format.
--diff-ini | --di: Display the non-default environment configuration on stdout using the ini format.
--full-env | --fe: Display the full environment configuration on stdout using the env format.
--diff-env | --de: Display the non-default configuration on stdout using the env format.
--run helper: Do not run ExaBGP but one of its helper programs, options are: healthcheck and cli
--debug | -d: Start the python debugger on serious logging on and on reception of the SIGTERM signal. This is a shortcut for exabgp.log.all=true and exabgp.log.level=DEBUG.
--validate: Validate the configuration file format only.
--signal time: Issue a SIGUSR1 signal to reload the configuration after the specified number of seconds, only useful for code debugging.
--once | -1: Only perform one attempt to connect to peers, used mostly for debugging.
--pdb | -p: Start the python debugger on critical logging, reception of SIGTERM, and on uncaught python exceptions. This is a shortcut for exabgp.pdb.enable=true.
--memory | -s: Display memory usage information on program exit.
--profile profile: Enable collection of profiling information to the given file. This is a shortcut for exabgp.profile.enable=true and exabgp.profile.file=profile.
--test | -t: Only do a configuration validity check.
--decode hex-message | -x hex-message: Decode a raw route packet in hexadecimal string.

ENVIRONMENT

The configuration of exabgp is split in two:

The environment configuration which controls the basic execution of exabgp such as logging, daemonizing, pid-file, profiling etc.
The BGP configuration of exabgp, which specifies which neighbors it should talk BGP with and all other aspects of the BGP configuration.

The environment configuration can be specified a number of different ways, with different priority:

Command line values using dot-separated notation.
Environment variables using dot-separated notation.
Command line values using underscore-separated notation.
Environment variables using underscore-seprated notation.
The values from the ini configuration file, /etc/exabgp/exabgp.env
The built-in default values.

The following environment variables can be used to configure the basic execution of exabgp:

exabgp.api.encoder: (experimental) default encoder to use with external API (text or json). Default: text.
exabgp.api.highres: Controls whether to use high-resolution timestamps in JSON. Default: false.
exabgp.api.respawn: Controls whether to respawn a helper process if it dies. Default: false.
exabgp.bgp.openwait: Controls how many seconds we should wait for a BGP open message once the TCP session is established. Default: 60 seconds.
exabgp.cache.attributes: Controls whether all attributes (configuration and wire) should be cached for faster parsing. Default: true.
exabgp.cache.nexthops: (deprecated) Controls whether route next-hops are cached. Default: true.
exabgp.daemon.daemonize: Controls whether exabgp should run in the background. Default: false.
exabgp.daemon.pid: Where to save the PID of exabgp if we manage it. Default: '' (not set).
exabgp.daemon.user: The user to run exabgp as. Should be an unprivileged user. Default: nobody.
exabgp.log.all: Controls whether debug logging should be done for everything. Default: false.
exabgp.log.configuration: Controls whether logging should be done for the configuration and command parsing. Default: true.
exabgp.log.daemon: Controls whether logging should be done for PID change, forking, etc. Default: true.
exabgp.log.destination: Controls where logging should be sent. syslog (or no setting) sends the data to the local syslog server. host:<location> sends the data to a remote syslog server. stdout sends the data to stdout. stderr sends the data to stderr. <filename> sends the data to the named file. Default: stdout.
exabgp.log.enable: Controls whether logging should be done. Default: true.
exabgp.log.level: Sets the minimum severity level to log. Default: INFO.
exabgp.log.message: Controls logging of changes in route announcement in config reload. Default: false.
exabgp.log.network: Controls logging of networking information (TCP/IP state, network state etc.). Default: true.
exabgp.log.packets: Controls logging of BGP packets sent and received. Default: false.
exabgp.log.parser: Controls logging of BGP message parsing details. Default: false.
exabgp.log.processes: Controls logging of forked processes. Default: true.
exabgp.log.reactor: Controls logging of signals received and command reload. Default: true.
exabgp.log.rib: Controls logging of changes in locally configured routes. Default: false.
exabgp.log.routes: Controls logging of received routes. Default: false.
exabgp.log.short: Coontrols whether to use long or short log format (not prepended with time, level, pid and source). Default: false.
exabgp.log.timers: Controls logging of keepalive timers. Default: false.
exabgp.pdb.enable: Controls whether pdb, the python interactive debugger should be started on program faults. Default: false.
exabgp.profile.enable: Controls whether profiling of the code should be done. Default: false.
exabgp.profile.file: Controls where profiling results should be written. None/empty means stdout. Default: empty.
exabgp.reactor.speed: Controls the time of one reactor loop. Use only if you understand the code. Default: 1.0.
exabgp.tcp.acl: (experimental, unimplemented). Default: empty.
exabgp.tcp.bind: IP address to bind to when listening (no ip to disable). Default: empty.
exabgp.tcp.delay: Start to announce routes when the minutes in the hour is a modulo of this number. Default: 0.
exabgp.tcp.once: Only perform one TCP connection attempt per peer, for debugging scripts. Default: false.
exabgp.tcp.port: Port to bind to when listening. Default: 179.

FILES

/etc/exabgp/exabgp.env is the default file for setting the "environment" variables controlling the execution of exabgp. An alaternative "env" configuration file can be supplied via the --env env-config argument. The format of this file is "Windows INI format". All the default settings can be shown with the exabgp --test --full-init command, an example showing parts of this output is:

[exabgp.api]
encoder = text
highres = false
respawn = false

[exabgp.bgp]
openwait = 60

Additionally, the user will need to supply a configuration file controlling the BGP configuration of exabgp, in the format described in exabgp.conf(5).

SIGNALS

exabgp catches a few different signals to control specific actions. They are:

ALRM: Restarts exabgp.
USR1: Causes exabgp to reload the configuration.
USR2: Causes exabgp to reload the configuration and restart any forked processes.
TERM: Terminates exabgp.
HUP: Also terminates exabgp (does not reload the configuration anymore).

Reloading large configurations using signals is currently not recommended, because the configuration parsing code is currently blocking. Therefore if you have a large configuration change, it could cause the peer to miss some keepalive and cause a session flap.

DIAGNOSTICS

The --test argument is useful to validate the syntax of the configuration file. The --debug flag will provide copious debug output to whereever the various exabgp.log variable settings dictate.

STANDARDS

A list of the standards exabgp implements which is indicative of the features implemented is:

RFC 4893: BGP Support for Four-octet AS Number Space
RFC 4760: Multiprotocol Extension for BGP-4
RFC 4659: BGP-MPLS IP Virtual Private Network (VPN) Extension for IPv6 VPN
RFC 4762: Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signalling
RFC 5575: Dissemination of Flow Specification Rules
RFC 4724: Graceful Restart Mechanism for BGP
RFC 7313: Enhanced Route Refresh Capability for BGP-4
RFC 7311: The Accumulated IGP Metric Attribute for BGP
draft-raszuk-idr-flow-spec-v6-03: (draft-ietf-idr-flow-spec-v6-06), Dissemination of Flow Specification Rules for IPv6
draft-simpson-idr-flowspec-redirect-00 (-02): BGP Flow-Spec Redirect to IP Action
draft-ietf-idr-flowspec-redirect-00 (-02): BGP Flow-Spec Redirect to IP Action
draft-ietf-idr-add-paths-08 (-10): Advertisement of Multiple Paths in BGP
draft-ietf-idr-bgp-multisession-07 (??)
draft-scudder-bmp-01 (??)

A list of other more basic BGP-related standard entirely or partially implemented is:

RFC 1997: BGP Communities Attribute
RFC 8092: BGP Large Communities Attribute
RFC 2385: Protection of BGP Sessions via the TCP MD5 Signature
RFC 2545: Use of BGP-4 Multirptocol Extensions for IPv6 Inter-Domain Routing
RFC 2918: Route Refresh Capability for BGP-4
RFC 3107: Carrying Label Information in BGP-4
RFC 3765: NOPEER Community for Border Gateway Protocol (BGP) Route Scope Control
RFC 7999: BLACKHOLE BGP Community for Blackholing
RFC 4271: A Border Gateway Protocol 4 (BGP-4)
RFC 4360: BGP Extended Communities Attribute
RFC 4364: Constrained Route Distribution for BGP/MPLS IP VPNs
RFC 4456: BGP Rotue Relection: An Alternative to Full Mesh Internal BGP (iBGP)
RFC 5396: Textual Representation of Autonomous System (AS) Numbers
RFC 5492: Capabilities Advertisement with BGP-4
RFC 6286: Autonomous-System-Wide Unique BGP Identifier for BGP-4
RFC 6608: Subcodes for BGP Finate State Machine Error
RFC 7752: North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP
draft-gredler-idr-bgp-ls-segment-routing-ext-03: BGP Link-State extensions for Segment Routing
draft-ietf-idr-bgp-prefix-sid-05: Segment Routing Prefix SID extensions for BGP

February 26, 2015