bagpipe-bgp 1.80.0

Description:

bagpipebgp 1.80.0

BaGPipe BGP
BaGPipe BGP is a lightweight implementation of BGP VPNs (IP VPNs and
E-VPNs), targeting deployments on servers hosting VMs, in particular for
Openstack/KVM platforms.
The goal is not to fully implement BGP specifications, but only the
subset of specifications required to implement IP VPN VRFs and E-VPN
EVIs (RFC4364 a.k.a RFC2547bis,
RFC7432/draft-ietf-bess-evpn-overlay,
and RFC4684).
BaGPipe BGP is designed to use encapsulations over IP (such as
MPLS-over-GRE or VXLAN), and thus does not require the use of LDP. Bare
MPLS over Ethernet is also supported and can be used if servers/routers
have direct Ethernet connectivity.

Typical Use
BaGPipe-BGP has been designed to provide VPN (IP VPN or E-VPN)
connectivity to VMs running on a local server.
The target is to provide VPN connectivity to VMs deployed by Openstack.
A typical target architecture is to have BaGPipe-BGP be driven by
Openstack Neutron components:

the bagpipe driver for the BGP VPN interconnection service
plugin
the bagpipe ML2 mechanism
driver using E-VPN

BaGPipe-BGP can also be used standalone (e.g. for testing purposes),
with for instance VMs tap interfaces or veth interfaces to network
namespaces (see below).


Installation
Installation can be done with python setup.py install.
Running install.sh will take care of this and will also install
startup scripts in /etc/init.d and sample config files in
/etc/bagpipe-bgp.


BGP and Route Reflection
If you only want to test how to interconnect one server running
bagpipe-bgp and an IP/MPLS router, you don’t need to setup a BGP Route
Reflector. But to use BaGPipe BGP on more than one server, the current
code currently requires setting up a BGP Route Reflector (see
Caveats).
The term “BGP Route Reflector” refers to a BGP implementation that
redistribute routes between iBGP peers
RFC4456.
When using bagpipe-bgp on more than one server, we thus need each
instance of BaGPipe BGP to be configured to peer with at least one route
reflector (see Configuration).
We provide a tool that can be used to emulate a route reflector to
interconnect 2 BaGPipe BGP implementations, typically for test
purposes (see Fake RR).
For more than 2 servers running BaGPipe BGP, you will need a real BGP
implementation supporting RFC4364 and BGP route reflection (and ideally
also RFC4684).
Different options can be considered:

A router from for instance, Alcatel-Lucent, Cisco or Juniper can be
used; some of these vendors also provide their OSes as virtual
machines
BGP implementations in other opensource projects would possibly be
suitable, but we did not explore i these exhaustively:

there has been some work to allow the use of OpenContrail’s BGP
implementation as a Route Reflector; although this is currently
unfinished, we have done rough hacks to confirm the feasibility
and the interoperability
GoBGP team has sucessfully
deployed a setup with GoBGP as a RR for bagpipe-bgp PE
implementations, with
E-VPN
we have sucessfully used OpenBSD BGPd as an IP VPN RR for
bagpipe-bgp
Quagga is supposed to support IP VPNs (untested AFAIK)





Configuration
The bagpipe-bgp daemon config file default location is:
/etc/bagpipe-bgp/bgp.conf.
The install.sh script will install a template as an example
configuration.
It needs to be customized, at least for the following:

local_address: the local address to use for BGP sessions and traffic
encapsulation
peers: the list of BGP peers, it depends on the BGP setup that you
have chosen (see above BGP Route Reflection)
dataplane configuration, if you really want packets to get through
(see Dataplane configuration)

Example with two servers and relying on bagpipe fake route reflector:

On server A (local_address=10.0.0.1):

run bagpipe-fakerr
run bagpipe-bgp with peers=127.0.0.1 (server A will thus connect to the locally running fake route-reflector)


On server B (local_address=10.0.0.2):

run bagpipe-bgp with peers=10.0.0.1




Dataplane driver configuration
Note well that the dataplane drivers proposed in the sample config file
are dummy drivers that will not actually drive any dataplane
state. To have traffic really forwarded into IP VPNs or E-VPNs, you need
to select real dataplane drivers.
For instance, you can use the
mpls_ovs_dataplane.MPLSOVSDataplaneDriver for IP VPN, and the
linux_vxlan.LinuxVXLANDataplaneDriver for E-VPN.
Note well that there are specific constraints on which dataplane
drivers can currently be used for IP VPNs:

the MPLSOVSDataplaneDriver can be used on most recent Linux kernels,
but requires an OpenVSwitch with suitable MPLS code (OVS 2.4 was
tested); this driver can do bare-MPLS or MPLS-over-GRE (but see
Caveats for MPLS-over-GRE); for bare MPLS, this driver
requires the OVS bridge to be associated with an IP address, and that
VRF interfaces be plugged into OVS prior to calling BaGPipe BGP API
to attach them (details in
mpls_ovs_dataplane.py)
(the MPLSLinuxDataplaneDriver is based on an unmaintained MPLS stack
for the Linux 3.7 kernel, and should be considered obsolete ; see
mpls_linux_dataplane.py)

For E-VPN, the linux_vxlan.LinuxVXLANDataplaneDriver is usable
without any particular additional configuration, and simply requires a
Linux kernel >=3.10 with VXLAN compiled-in or provided as a module
(linux_vxlan.py).



Usage

BaGPipe BGP daemon
If init scripts are installed, the daemon is typically started with:
service bagpipe-bgp start
It can also be started directly with the bagpipe-bgp command
(--help to see what parameters can be used; e.g. --no-deamon).
It outputs logs in /var/log/bagpipe-bgp/bagpipe-bgp.log.


BaGPipe Fake BGP Route Reflector
If you choose to use our fake BGP Route Reflector (see BGP Route
Reflection), you can start it whether with the
bagpipe-fakerr command, or if you have startup scripts installed,
with service bagpipe-bgp start.
There isn’t anything to configure, logs will be in syslog.
This tool is not a BGP implementation and simply plugs together two TCP
connections face to face.


REST API tool for interface attachments
The bagpipe-rest-attach tool allows to exercise the REST API through
the command line to attach and detach interfaces from ip VPN VRFs and
E-VPN EVIs.
See bagpipe-rest-attach --help.

IP VPN example with a VM tap interface
This example assumes that there is a pre-existing tap interface ‘tap42’.

on server A, plug tap interface tap42, MAC de:ad:00:00:be:ef, IP
11.11.11.1 into an IP VPN VRF with route-target 64512:77:
bagpipe-rest-attach --attach --port tap42 --mac de:ad:00:00:be:ef --ip 11.11.11.1 --gateway-ip 11.11.11.254 --network-type ipvpn --rt 64512:77

on server B, plug tap interface tap56, MAC ba:d0:00:00:ca:fe, IP
11.11.11.2 into an IP VPN VRF with route-target 64512:77:
bagpipe-rest-attach --attach --port tap56 --mac ba:d0:00:00:ca:fe --ip 11.11.11.2 --gateway-ip 11.11.11.254 --network-type ipvpn --rt 64512:77


Note that this example is a schoolbook example only, but does not
actually work unless you try to use one of the two MPLS Linux dataplane
drivers.
Note also that, assuming that VMs are behind these tap interfaces, these
VMs will need to have proper IP configuration. When BaGPipe BGP is use
standalone, no DHCP service is provided, and the IP configuration will
have to be static.


Another IP VPN example…
In this example, the bagpipe-rest-attach tool will build for you a
network namespace and a properly configured pair of veth interfaces, and
will plug one of the veth to the VRF:

on server A, plug a netns interface with IP 12.11.11.1 into a new IP
VPN VRF named “test”, with route-target 64512:78
bagpipe-rest-attach --attach --port netns --ip 12.11.11.1 --network-type ipvpn --vpn-instance-id test --rt 64512:78

on server B, plug a netns interface with IP 12.11.11.2 into a new IP
VPN VRF named “test”, with route-target 64512:78
bagpipe-rest-attach --attach --port netns --ip 12.11.11.2 --network-type ipvpn --vpn-instance-id test --rt 64512:78


For this last example, assuming that you have configured bagpipe-bgp to
use the MPLSOVSDataplaneDriver for IP VPN, you will actually be able
to have traffic exchanged between the network namespaces:
ip netns exec test ping 12.11.11.2
PING 12.11.11.2 (12.11.11.2) 56(84) bytes of data.
64 bytes from 12.11.11.2: icmp_req=6 ttl=64 time=1.08 ms
64 bytes from 12.11.11.2: icmp_req=7 ttl=64 time=0.652 ms


An E-VPN example
In this example, similarly as the previous one, the bagpipe-rest-attach
tool will build for you a network namespace and a properly configured
pair of veth interfaces, and will plug one of the veth to the E-VPN
instance:

on server A, plug a netns interface with IP 12.11.11.1 into a new
E-VPN named “test2”, with route-target 64512:79
bagpipe-rest-attach --attach --port netns --ip 12.11.11.1 --network-type evpn --vpn-instance-id test2 --rt 64512:79

on server B, plug a netns interface with IP 12.11.11.2 into a new
E-VPN named “test2”, with route-target 64512:79
bagpipe-rest-attach --attach --port netns --ip 12.11.11.2 --network-type evpn --vpn-instance-id test2 --rt 64512:79


For this last example, assuming that you have configured bagpipe-bgp to
use the linux_vxlan.LinuxVXLANDataplaneDriver for E-VPN, you will
actually be able to have traffic exchanged between the network
namespaces:
ip netns exec test2 ping 12.11.11.2
PING 12.11.11.2 (12.11.11.2) 56(84) bytes of data.
64 bytes from 12.11.11.2: icmp_req=1 ttl=64 time=1.71 ms
64 bytes from 12.11.11.2: icmp_req=2 ttl=64 time=1.06 ms



Looking glass
The REST API (default port 8082) provide troubleshooting information, in
read-only, through the /looking-glass URL.
It can be accessed with a browser: e.g.
http://10.0.0.1:8082/looking-glass or
http://127.0.0.1:8082/looking-glass (a browser extension to nicely
display JSON data is recommended).
It can also be accessed with the bagpipe-looking-glass utility:
# bagpipe-looking-glass
bgp: (...)
vpns: (...)
config: (...)
logs: (...)
summary:
warnings_and_errors: 2
start_time: 2014-06-11 14:52:32
local_routes_count: 1
BGP_established_peers: 0
vpn_instances_count: 1
received_routes_count: 0
# bagpipe-looking-glass bgp peers
* 192.168.122.1 (...)
state: Idle
# bagpipe-looking-glass bgp routes
match:IPv4/mpls-vpn,*:
* RD:192.168.122.101:1 12.11.11.1/32 MPLS:[129-B]:
attributes:
next_hop: 192.168.122.101
extended_community: target:64512:78
afi-safi: IPv4/mpls-vpn
source: VRF 1 (...)
route_targets:
* target:64512:78
match:IPv4/rtc,*:
* RTC<64512>:target:64512:78:
attributes:
next_hop: 192.168.122.101
afi-safi: IPv4/rtc
source: BGPManager (...)
match:L2VPN/evpn,*: -



Design overview
The main components of BaGPipe-BGP are:

the engine dispatching events related to BGP routes between workers
a worker for each BGP peers
a VPN manager managing the life-cycle of VRFs, EVIs
a worker for each IP VPN VRF, or E-VPN EVI
a REST API:

to attach/detach interfaces to VRFs and control the parameters for said VRFs
to access internal information useful for troubleshooting (/looking-glass/ URL sub-tree)




Publish/Subscribe design
The engine dispatching events related to BGP routes is designed with a
publish/subscribe pattern based on the principles in
RFC4684. Workers (a worker can
be a BGP peer or a local worker responsible for an IP VPN VRF) publish
BGP VPN routes with specified Route Targets, and subscribe to the Route
Targets that they need to receive. The engine takes care of propagating
advertisement and withdrawal events between the workers, based on
subscriptions and BGP semantics (e.g. no redistribution between BGP
peers sessions).


Best path selection
The core engine does not do any BGP best path selection. For routes
received from external BGP peers, best path selection happens in the VRF
workers. For routes that local workers advertise, no best path selection
is done because two distinct workers will never advertise a route of
same BGP NLRI.


Multi-threading
For implementation convenience, the design choice was made to use Python
native threads and python Queues to manage the API, local workers, and
BGP peers workloads:

the engine (RouteTableManager) is running as a single thread
each local VPN worker has its own thread to process route events
each BGP peer worker has two threads to process outgoing route
events, and receive socket data, plus a few timers.
VPN port attachement actions are done in the main thread handling
initial setup and API calls, these calls are protected by Python
locks



Non-persistency of VPN and port attachements
The BaGPipe BGP daemon, as currently designed, does not persist
information on VPNs (VRFs or EVIs) and the ports attached to them. On a
restart, the component responsible triggering the attachement of
interfaces to VPNs, can detect the restart of the BGP daemon and
re-trigger these attachements.


BGP Implementation
The BGP protocol implementation extends an reuses BGP code from
ExaBGP. Information about what was
modified in ExaBGP is in README.exabgp. BaGPipe BGP
only reuses the low-level Connection and Protocol classes, with
additions to encode and decode NLRI and attribute specific to BGP VPN
extensions.
Non-goals for this BGP implementation:

full-fledged BGP implementation
redistribution of routes between BGP peers (hence, no route reflection, no eBGP)
accepting incoming BGP connections
scaling to a number of routes beyond the number of routes required to
route traffic in/out of VMs hosted on a server running BaGPipe



Dataplanes
BaGPIpe BGP was designed to allow for a modular dataplane
implementation. For each type of VPN (IP VPN, E-VPN) a dataplane driver
is chosen through configuration. A dataplane driver is responsible for
setting up forwarding state for incoming and outgoing traffic based on
port attachement information and BGP routes.
(see Dataplane driver configuration)



Caveats

release early, release often: not everything is perfect yet
BGP implementation not written for compliancy



the BaGPipe BGP daemon does not listen for incoming BGP connections
the state machine, in particular retry timers are certainly not compliant yet
however, interop testing has been done with a fair amount of implementations



MPLS-over-GRE is supported for IP VPNs, but is not yet standard (OpenVSwitch currently does MPLS-o-Ethernet-o-GRE and not MPLS-o-GRE)



Unit Tests
Unit tests can be run with:
nosetests
A report of unit tests coverage can be produced with:
nosetests --with-coverage --cover-package=bagpipe.bgp --cover-html


License
Apache 2.0 license (except additions and modifications to ExaBGP,
licensed as 3-Clause BSD license).
See LICENSE file.