This guide describes how to enable Network isolation provided through the VXLAN encapsulation protocol. This driver will create a bridge for each OpenNebula Virtual Network and attach a VXLAN tagged network interface to the bridge.
The VLAN id will be the same for every interface in a given network, calculated automatically by OpenNebula. It may also be forced by specifying an VLAN_ID parameter in the Virtual Network template.
Additionally each VLAN has associated a multicast address to encapsulate L2 broadcast and multicast traffic. This address is assigned by default to the 126.96.36.199/8 range as defined by RFC 2365 (Administratively Scoped IP Multicast). In particular the multicast address is obtained by adding the VLAN_ID to the 188.8.131.52/8 base address.
Considerations & Limitations¶
This driver works with the default UDP server port 8472.
VXLAN traffic is forwarded to a physical device, this device can be set (optionally) to be a VLAN tagged interface, but in that case you must make sure that the tagged interface is manually created first in all the hosts.
The physical device that will act as the physical device must have an IP.
Concurrent VXLANs host limit¶
Each VXLAN is associated with one multicast group. There is a limit on how many multicast groups can be a physical host member of at the same time. That also means, how many different VXLANs can be used on a physical host concurrently. The default value is 20 and can be changed via
sysctl through kernel runtime parameter
For permanent change to e.g. 150, place following settings inside the
and reload the configuration
sudo sysctl -p
It is possible specify the start VLAN ID by configuring
# VXLAN_IDS: Automatic VXLAN Network ID (VNI) assigment. This is used # for vxlan networks. # start: First VNI to use VXLAN_IDS = [ START = "2" ]
The following configuration attributes can be adjusted in
|vxlan_mc||Base multicast address for each VLAN. The multicas sddress is vxlan_mc + vlan_id|
|vxlan_ttl||Time To Live (TTL) should be > 1 in routed multicast networks (IGMP)|
|validate_vlan_id||Set to true to check that no other vlans are connected to the bridge|
|keep_empty_bridge||Set to true to preserve bridges with no virtual interfaces left.|
|bridge_conf||Hash Options for
|ip_bridge_conf||Hash Options for ip-route2
|ip_link_conf||Hash Arguments passed to
# Following options will be added when creating bridge. For example: # # ip link add name <bridge name> type bridge stp_state 1 # # :ip_bridge_conf: # :stp_state: on # These options will be added to the ip link add command. For example: # # sudo ip link add lxcbr0.260 type vxlan id 260 group 184.108.40.206 \ # ttl 16 dev lxcbr0 udp6zerocsumrx tos 3 # :ip_link_conf: :udp6zerocsumrx: :tos: 3
Defining a VXLAN Network¶
To create a VXLAN network include the following information:
|PHYDEV||Name of the physical network device that will be attached to the bridge.||YES|
|BRIDGE||Name of the linux bridge, defaults to onebr<net_id> or onebr.<vlan_id>||NO|
|VLAN_ID||The VLAN ID, will be generated if not defined||NO|
|AUTOMATIC_VLAN_ID||Mandatory if VLAN_ID is not defined, in order to get OpenNebula to asign an ID||NO|
|MTU||The MTU for the tagged interface and bridge||NO|
The following example defines a VXLAN network
NAME = "vxlan_net" VN_MAD = "vxlan" PHYDEV = "eth0" VLAN_ID = 50 # optional BRIDGE = "vxlan50" # optional ...
In this scenario, the driver will check for the existence of the
vxlan50 bridge. If it doesn’t exist it will be created.
eth0 will be tagged (
eth0.50) and attached to
vxlan50 (unless it’s already attached). Note that eth0 can be a 802.1Q tagged interface if you want to isolate the OpenNebula VXLAN traffic.
Using VXLAN with BGP EVPN¶
By default VXLAN relies on multicast to discover tunnel endpoints, alternatively you can use MP-BGP EVPN for the control plane and hence increase the scalability of your network. This section describes the main configuration steps to deploy such setup.
Configuring the Hypervisors¶
The hypervisor needs to run a BGP EVPN capable routing software like FFRouting (FRR). Its main purpose is to send BGP updates with the MAC address and IP (optional) for each VXLAN tunnel endpoint (i.e. the VM interfaces in the VXLAN network) running in the host. The updates needs to be distributed to all other hypervisors in the cloud to achieve full route reachability. This second step is usually performed by one or more BGP route reflectors.
As an example, consider two hypervisors 10.4.4.11 and 10.4.4.12, and a route reflector at 10.4.4.13. The FRR configuration file for the hypervisors could be (to announce all VXLAN networks):
router bgp 7675 bgp router-id 10.4.4.11 no bgp default ipv4-unicast neighbor 10.4.4.13 remote-as 7675 neighbor 10.4.4.13 capability extended-nexthop address-family l2vpn evpn neighbor 10.4.4.13 activate advertise-all-vni exit-address-family exit
And the reflector for our AS 7675, and hypervisors in 10.4.4.0/24:
router bgp 7675 bgp router-id 10.4.4.13 bgp cluster-id 10.4.4.13 no bgp default ipv4-unicast neighbor kvm_hosts peer-group neighbor kvm_hosts remote-as 7675 neighbor kvm_hosts capability extended-nexthop neighbor kvm_hosts update-source 10.4.4.13 bgp listen range 10.4.4.0/24 peer-group kvm_hosts address-family l2vpn evpn neighbor fabric activate neighbor fabric route-reflector-client exit-address-family exit
Note that this a simple scenario using the same configuration for all the VNIs. Once the routing software is configure you should see the updates in each hypervisor for the VMs running in it, for example:
10.4.4.11# show bgp evpn route Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 10.4.4.11:2 *> ::::[02:00:0a:03:03:c9] 10.4.4.11 32768 i *> :::[10.4.4.11] 10.4.4.11 32768 i Route Distinguisher: 10.4.4.12:2 *>i::::[02:00:0a:03:03:c8] 10.4.4.12 0 100 0 i *>i:::[10.4.4.12] 10.4.4.12 0 100 0 i
You need to update
/var/lib/one/remotes/vnm/OpenNebulaNetwork.conf file to:
- Set BGP EVPN as the control plane for your BUM traffic,
- Select the hypervisor is going to send the traffic to the VTEP. This can be either
dev, to forward the traffic through the
PHY_DEVinterface defined in the Virtual Network template, or
local_ipto route the traffic using the first IP configured in
- Finally you may want to add the nolearning option to the VXLAN link.
# Multicast protocol for multi destination BUM traffic. Options: # - multicast, for IP multicast # - evpn, for BGP EVPN control plane :vxlan_mode: evpn # Tunnel endpoint communication type. Only for evpn vxlan_mode. # - dev, tunnel endpoint communication is sent to PHYDEV # - local_ip, first ip addr of PHYDEV is used as address for the communiation :vxlan_tep: local_ip # Additional ip link options, uncomment the following to disable learning for # EVPN mode :ip_link_conf: :nolearning:
After updating the configuration file do not forget to run onehost sync -f to distribute the changes.