Lightweight Network Virtualization Overview

Lightweight Network Virtualization (LNV) is a technique for deploying VXLANs without a central controller on bare metal switches. This solution requires no external controller or software suite; it runs the VXLAN service and registration daemons on Cumulus Linux itself. The data path between bridge entities is established on top of a layer 3 fabric by means of a simple service node coupled with traditional MAC address learning.

To see an example of a full solution before reading the following background information, read this chapter.

LNV Concepts

Consider the following example deployment:

The two switches running Cumulus Linux, called leaf1 and leaf2, each have a bridge configured. These two bridges contain the physical switch port interfaces connecting to the servers as well as the logical VXLAN interface associated with the bridge. By creating a logical VXLAN interface on both leaf switches, the switches become VTEPs (virtual tunnel end points). The IP address associated with this VTEP is most commonly configured as its loopback address; in the image above, the loopback address is 10.2.1.1 for leaf1 and 10.2.1.2 for leaf2.

Acquire the Forwarding Database at the Service Node

To connect these two VXLANs together and forward BUM (Broadcast, Unknown-unicast, Multicast) packets to members of a VXLAN, the service node needs to acquire the addresses of all the VTEPs for every VXLAN it serves. The service node daemon does this through a registration daemon running on each leaf switch that contains a VTEP participating in LNV. The registration process informs the service node of all the VXLANs to which the switch belongs.

MAC Learning and Flooding

With LNV, as with traditional bridging of physical LANs or VLANs, a bridge automatically learns the location of hosts as a side effect of receiving packets on a port.

For example, when server1 sends a layer 2 packet to server3, leaf2 learns that the MAC address for server1 is located on that particular VXLAN and the VXLAN interface learns that the IP address of the VTEP for server1 is 10.2.1.1. So when server3 sends a packet to server1, the bridge on leaf2 forwards the packet out of the port to the VXLAN interface and the VXLAN interface sends it, encapsulated in a UDP packet, to the address 10.2.1.1.

But what if server3 sends a packet to some address that has yet to send it a packet (server2, for example)? In this case, the VXLAN interface sends the packet to the service node, which sends a copy to every other VTEP that belongs to the same VXLAN. This is called service node replication and is one of two techniques for handling BUM (Broadcast Unknown-unicast and Multicast) traffic.

BUM Traffic

Cumulus Linux has two ways of handling BUM (Broadcast Unknown-unicast and Multicast) traffic:

• Head end replication
• Service node replication

Head end replication is enabled by default in Cumulus Linux.

Head End Replication

Broadcom switches with Tomahawk, Trident II+, and Trident II ASICs and switches with Spectrum ASICs are capable of head end replication (HER), which is the ability to generate all the BUM traffic in hardware. The most scalable solution available with LNV is to have each VTEP (top of rack switch) generate all of its own BUM traffic instead of relying on an external service node. HER is enabled by default in Cumulus Linux.

Cumulus Linux verified support for up to 128 VTEPs with head end replication.

To disable head end replication, edit the /etc/vxrd.conf file and set head_rep to False.

Service Node Replication

Cumulus Linux also supports service node replication for VXLAN BUM packets. This is useful with LNV if you have more than 128 VTEPs. However, it is not recommended because it forces the spine switches running the vxsnd (service node daemon) to replicate the packets in software instead of in hardware, unlike head end replication.

To enable service node replication:

1. Disable head end replication; set head_rep to False in the /etc/vxrd.conf file.

2. Configure a service node IP address for every VXLAN interface using the vxlan-svcnodeip parameter:

   cumulus@switch:~$ net add vxlan VXLAN vxlan svcnodeip IP_ADDRESS
   

   You only specify this parameter when head end replication is disabled. For the loopback, the parameter is still named vxrd-svcnode-ip.

3. Edit the /etc/vxsnd.conf file and configure the following:

   • Set the same service node IP address that you configured in the previous step:

     svcnode_ip = <>
     

   • To forward VXLAN data traffic, set the following variable to True:

     enable_vxlan_listen = true
     

Requirements

Hardware Requirements

Switches with the Broadcom Tomahawk, Trident II+, or Trident II ASIC or switches with the Mellanox Spectrum ASIC running Cumulus Linux 2.5.4 or later. Refer to the hardware compatibility list for a list of supported switch models.

Configuration Requirements

• The VXLAN has an associated VXLAN Network Identifier (VNI), also interchangeably called a VXLAN ID.
• The VNI cannot be 0 or 16777215, as these two numbers are reserved values under Cumulus Linux.
• The VXLAN link and physical interfaces are added to the bridge to create the association between the port, VLAN, and VXLAN instance.
• Each bridge on the switch has only one VXLAN interface. Cumulus Linux does not support more than one VXLAN link in a bridge; however, a switch can have multiple bridges.
• An SVI (Switch VLAN Interface) or layer 3 address on the bridge is not supported. For example, you cannot ping from the leaf1 SVI to the leaf2 SVI through the VXLAN tunnel; you need to use server1 and server2 to verify.

Install the LNV Packages

vxfld is installed by default on all new installations of Cumulus Linux 3.x. If you are upgrading from an earlier version, run sudo -E apt-get install python-vxfld to install the LNV package.

Sample LNV Configuration

The following images illustrate the configuration that is referenced throughout this chapter.

Physical Cabling Diagram	Network Virtualization Diagram

Network Connectivity

There must be full network connectivity before you can configure LNV. The layer 3 IP addressing information as well as the OSPF configuration (/etc/frr/frr.conf) below is provided to make the LNV example easier to understand.

Layer 3 IP Addressing

Here is the configuration for the IP addressing information used in this example.

cumulus@spine1:~$ net add interface swp49 ip address 10.1.1.2/30
cumulus@spine1:~$ net add interface swp50 ip address 10.1.1.6/30
cumulus@spine1:~$ net add interface swp51 ip address 10.1.1.50/30
cumulus@spine1:~$ net add interface swp52 ip address 10.1.1.54/30
cumulus@spine1:~$ net add loopback lo ip address 10.2.1.3/32
cumulus@spine1:~$ net pending
cumulus@spine1:~$ net commit

cumulus@spine1:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
  address 10.2.1.3/32
auto eth0
iface eth0 inet dhcp
auto swp49
iface swp49
address 10.1.1.2/30
auto swp50
iface swp50
address 10.1.1.6/30
auto swp51
iface swp51
address 10.1.1.50/30
auto swp52
iface swp52
address 10.1.1.54/30

cumulus@spine2:~$ net add interface swp49 ip address 10.1.1.18/30
cumulus@spine2:~$ net add interface swp50 ip address 10.1.1.22/30
cumulus@spine2:~$ net add interface swp51 ip address 10.1.1.34/30
cumulus@spine2:~$ net add interface swp52 ip address 10.1.1.38/30
cumulus@spine2:~$ net add loopback lo ip address 10.2.1.4/32
cumulus@spine2:~$ net pending
cumulus@spine2:~$ net commit

cumulus@spine2:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
  address 10.2.1.4/32
auto eth0
iface eth0 inet dhcp
auto swp49
iface swp49
address 10.1.1.18/30
auto swp50
iface swp50
address 10.1.1.22/30
auto swp51
iface swp51
address 10.1.1.34/30
auto swp52
iface swp52
address 10.1.1.38/30

cumulus@leaf1:~$ net add interface swp1 breakout 4x
cumulus@leaf1:~$ net add interface swp1s0 ip address 10.1.1.1/30
cumulus@leaf1:~$ net add interface swp1s1 ip address 10.1.1.5/30
cumulus@leaf1:~$ net add interface swp1s2 ip address 10.1.1.33/30
cumulus@leaf1:~$ net add interface swp1s3 ip address 10.1.1.37/30
cumulus@leaf1:~$ net add loopback lo ip address 10.2.1.1/32
cumulus@leaf1:~$ net pending
cumulus@leaf1:~$ net commit

cumulus@leaf1:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
  address 10.2.1.1/32
auto eth0
iface eth0 inet dhcp
auto swp1s0
iface swp1s0
address 10.1.1.1/30
auto swp1s1
iface swp1s1
address 10.1.1.5/30
auto swp1s2
iface swp1s2
address 10.1.1.33/30
auto swp1s3
iface swp1s3
address 10.1.1.37/30

cumulus@leaf2:~$ net add interface swp1 breakout 4x
cumulus@leaf2:~$ net add interface swp1s0 ip address 10.1.1.17/30
cumulus@leaf2:~$ net add interface swp1s1 ip address 10.1.1.21/30
cumulus@leaf2:~$ net add interface swp1s2 ip address 10.1.1.49/30
cumulus@leaf2:~$ net add interface swp1s3 ip address 10.1.1.53/30
cumulus@leaf2:~$ net add loopback lo ip address 10.2.1.2/32
cumulus@leaf2:~$ net pending
cumulus@leaf2:~$ net commit 

cumulus@leaf2:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback
  address 10.2.1.2/32
auto eth0
iface eth0 inet dhcp
auto swp1s0
iface swp1s0
address 10.1.1.17/30
auto swp1s1
iface swp1s1
address 10.1.1.21/30
auto swp1s2
iface swp1s2
address 10.1.1.49/30
auto swp1s3
iface swp1s3
address 10.1.1.53/30

Layer 3 Fabric

The service nodes and registration nodes must all be routable between each other. The layer 3 fabric on Cumulus Linux can either be BGP or OSPF. In this example, OSPF is used to demonstrate full reachability. Click to expand the FRRouting configurations below.

cumulus@spine1:~$ net add ospf network 10.2.1.3/32 area 0.0.0.0
cumulus@spine1:~$ net add interface swp49 ospf network point-to-point
cumulus@spine1:~$ net add interface swp50 ospf network point-to-point
cumulus@spine1:~$ net add interface swp51 ospf network point-to-point
cumulus@spine1:~$ net add interface swp52 ospf network point-to-point
cumulus@spine1:~$ net add interface swp49 ospf area 0.0.0.0
cumulus@spine1:~$ net add interface swp50 ospf area 0.0.0.0
cumulus@spine1:~$ net add interface swp51 ospf area 0.0.0.0
cumulus@spine1:~$ net add interface swp52 ospf area 0.0.0.0
cumulus@spine1:~$ net add ospf router-id 10.2.1.3
cumulus@spine1:~$ net pending
cumulus@spine1:~$ net commit

interface swp49
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp50
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp51
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp52
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
router ospf
 ospf router-id 10.2.1.3
 network 10.2.1.3/32 area 0.0.0.0

cumulus@spine2:~$ net add ospf network 10.2.1.4/32 area 0.0.0.0
cumulus@spine2:~$ net add interface swp49 ospf network point-to-point
cumulus@spine2:~$ net add interface swp50 ospf network point-to-point
cumulus@spine2:~$ net add interface swp51 ospf network point-to-point
cumulus@spine2:~$ net add interface swp52 ospf network point-to-point
cumulus@spine2:~$ net add interface swp49 ospf area 0.0.0.0
cumulus@spine2:~$ net add interface swp50 ospf area 0.0.0.0
cumulus@spine2:~$ net add interface swp51 ospf area 0.0.0.0
cumulus@spine2:~$ net add interface swp52 ospf area 0.0.0.0
cumulus@spine2:~$ net add ospf router-id 10.2.1.4
cumulus@spine2:~$ net pending
cumulus@spine2:~$ net commit

interface swp49
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp50
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp51
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp52
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
router ospf
 ospf router-id 10.2.1.4
 network 10.2.1.4/32 area 0.0.0.0

cumulus@leaf1:~$ net add ospf network 10.2.1.1/32 area 0.0.0.0
cumulus@leaf1:~$ net add interface swp1s0 ospf network point-to-point
cumulus@leaf1:~$ net add interface swp1s1 ospf network point-to-point
cumulus@leaf1:~$ net add interface swp1s2 ospf network point-to-point
cumulus@leaf1:~$ net add interface swp1s3 ospf network point-to-point
cumulus@leaf1:~$ net add interface swp1s0 ospf area 0.0.0.0
cumulus@leaf1:~$ net add interface swp1s1 ospf area 0.0.0.0
cumulus@leaf1:~$ net add interface swp1s2 ospf area 0.0.0.0
cumulus@leaf1:~$ net add interface swp1s3 ospf area 0.0.0.0
cumulus@leaf1:~$ net add ospf router-id 10.2.1.1
cumulus@leaf1:~$ net pending
cumulus@leaf1:~$ net commit

interface swp1s0
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp1s1
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp1s2
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp1s3
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
router ospf
 ospf router-id 10.2.1.1
network 10.2.1.1/32 area 0.0.0.0

cumulus@leaf2:~$ net add ospf network 10.2.1.2/32 area 0.0.0.0
cumulus@leaf2:~$ net add interface swp1s0 ospf network point-to-point
cumulus@leaf2:~$ net add interface swp1s1 ospf network point-to-point
cumulus@leaf2:~$ net add interface swp1s2 ospf network point-to-point
cumulus@leaf2:~$ net add interface swp1s3 ospf network point-to-point
cumulus@leaf2:~$ net add interface swp1s0 ospf area 0.0.0.0
cumulus@leaf2:~$ net add interface swp1s1 ospf area 0.0.0.0
cumulus@leaf2:~$ net add interface swp1s2 ospf area 0.0.0.0
cumulus@leaf2:~$ net add interface swp1s3 ospf area 0.0.0.0
cumulus@leaf2:~$ net add ospf router-id 10.2.1.2
cumulus@leaf2:~$ net pending
cumulus@leaf2:~$ net commit

interface swp1s0
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp1s1
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp1s2
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
interface swp1s3
 ip ospf network point-to-point
 ip ospf area 0.0.0.0
!
router ospf
 ospf router-id 10.2.1.2
network 10.2.1.2/32 area 0.0.0.0

In this example, the servers are running Ubuntu 14.04. There needs to be a trunk mapped from server1 and server2 to the respective switch. In Ubuntu this is done with subinterfaces. You can expand the configurations below.

auto eth3.10
iface eth3.10 inet static
  address 10.10.10.1/24
auto eth3.20
iface eth3.20 inet static
address 10.10.20.1/24
auto eth3.30
iface eth3.30 inet static
address 10.10.30.1/24

auto eth3.10
iface eth3.10 inet static
  address 10.10.10.2/24
auto eth3.20
iface eth3.20 inet static
address 10.10.20.2/24
auto eth3.30
iface eth3.30 inet static
address 10.10.30.2/24

cumulus@server1:~$ sudo ifup eth3.10
Set name-type for VLAN subsystem. Should be visible in /proc/net/vlan/config
Added VLAN with VID == 10 to IF -:eth3:-
cumulus@server1:~$ sudo ifup eth3.20
Set name-type for VLAN subsystem. Should be visible in /proc/net/vlan/config
Added VLAN with VID == 20 to IF -:eth3:-
cumulus@server1:~$ sudo ifup eth3.30
Set name-type for VLAN subsystem. Should be visible in /proc/net/vlan/config
Added VLAN with VID == 30 to IF -:eth3:-

Configure the VLAN to VXLAN Mapping

Configure the VLANs and associated VXLANs. In this example, there are 3 VLANs and 3 VXLAN IDs (VNIs). VLANs 10, 20 and 30 are used and associated with VNIs 10, 2000 and 30 respectively. The loopback address, used as the vxlan-local-tunnelip, is the only difference between leaf1 and leaf2 for this demonstration.

cumulus@leaf1:~$ net add loopback lo ip address 10.2.1.1/32
cumulus@leaf1:~$ net add loopback lo vxrd-src-ip 10.2.1.1
cumulus@leaf1:~$ net add loopback lo vxrd-svcnode-ip 10.2.1.3
cumulus@leaf1:~$ net add vxlan vni-10 vxlan id 10
cumulus@leaf1:~$ net add vxlan vni-10 vxlan local-tunnelip 10.2.1.1
cumulus@leaf1:~$ net add vxlan vni-10 bridge access 10
cumulus@leaf1:~$ net add vxlan vni-2000 vxlan id 2000
cumulus@leaf1:~$ net add vxlan vni-2000 vxlan local-tunnelip 10.2.1.1
cumulus@leaf1:~$ net add vxlan vni-2000 bridge access 20
cumulus@leaf1:~$ net add vxlan vni-30 vxlan id 30
cumulus@leaf1:~$ net add vxlan vni-30 vxlan local-tunnelip 10.2.1.1
cumulus@leaf1:~$ net add vxlan vni-30 bridge access 30
cumulus@leaf1:~$ net add bridge bridge ports swp32s0.10
cumulus@leaf1:~$ net pending
cumulus@leaf1:~$ net commit

auto lo
iface lo
  address 10.2.1.1/32
  vxrd-src-ip 10.2.1.1
auto swp32s0.10
iface swp32s0.10
auto bridge
iface bridge
bridge-ports vni-10 vni-2000 vni-30
bridge-vids 10 20 30
bridge-vlan-aware yes
auto vni-10
iface vni-10
bridge-access 10
mstpctl-bpduguard yes
mstpctl-portbpdufilter yes
vxlan-id 10
vxlan-local-tunnelip 10.2.1.1
auto vni-2000
iface vni-2000
bridge-access 20
mstpctl-bpduguard yes
mstpctl-portbpdufilter yes
vxlan-id 2000
vxlan-local-tunnelip 10.2.1.1
auto vni-30
iface vni-30
bridge-access 30
mstpctl-bpduguard yes
mstpctl-portbpdufilter yes
vxlan-id 30
vxlan-local-tunnelip 10.2.1.1

cumulus@leaf2:~$ net add loopback lo ip address 10.2.1.2/32
cumulus@leaf2:~$ net add loopback lo vxrd-src-ip 10.2.1.2
cumulus@leaf2:~$ net add loopback lo vxrd-svcnode-ip 10.2.1.3
cumulus@leaf2:~$ net add vxlan vni-10 vxlan id 10
cumulus@leaf2:~$ net add vxlan vni-10 vxlan local-tunnelip 10.2.1.2
cumulus@leaf2:~$ net add vxlan vni-10 bridge access 10
cumulus@leaf2:~$ net add vxlan vni-2000 vxlan id 2000
cumulus@leaf2:~$ net add vxlan vni-2000 vxlan local-tunnelip 10.2.1.2
cumulus@leaf2:~$ net add vxlan vni-2000 bridge access 20
cumulus@leaf2:~$ net add vxlan vni-30 vxlan id 30
cumulus@leaf2:~$ net add vxlan vni-30 vxlan local-tunnelip 10.2.1.2
cumulus@leaf2:~$ net add vxlan vni-30 bridge access 30
cumulus@leaf1:~$ net add bridge bridge ports swp32s0.10
cumulus@leaf2:~$ net pending
cumulus@leaf2:~$ net commit

auto lo
iface lo
  address 10.2.1.2/32
  vxrd-src-ip 10.2.1.2
auto swp32s0.10
iface swp32s0.10
auto bridge
iface bridge
bridge-ports vni-10 vni-2000 vni-30
bridge-vids 10 20 30
bridge-vlan-aware yes
auto vni-10
iface vni-10
bridge-access 10
mstpctl-bpduguard yes
mstpctl-portbpdufilter yes
vxlan-id 10
vxlan-local-tunnelip 10.2.1.2
auto vni-2000
iface vni-2000
bridge-access 20
mstpctl-bpduguard yes
mstpctl-portbpdufilter yes
vxlan-id 2000
vxlan-local-tunnelip 10.2.1.2
auto vni-30
iface vni-30
bridge-access 30
mstpctl-bpduguard yes
mstpctl-portbpdufilter yes
vxlan-id 30
vxlan-local-tunnelip 10.2.1.2

Verify the VLAN to VXLAN Mapping

Use the brctl show command to see the physical and logical interfaces associated with that bridge:

cumulus@leaf1:~$ brctl show
bridge name bridge id           STP enabled     interfaces
bridge      8000.443839008404   yes             swp32s0.10
                                                vni-10
                                                vni-2000
                                                vni-30

As with any logical interfaces on Linux, the name does not matter (other than a 15-character limit). To verify the associated VNI for the logical name, use the ip -d link show command:

cumulus@leaf1:~$ ip -d link show vni-10
43: vni-10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-10 state UNKNOWN mode DEFAULT
    link/ether 02:ec:ec:bd:7f:c6 brd ff:ff:ff:ff:ff:ff
    vxlan id 10 srcport 32768 61000 dstport 4789 ageing 1800
    bridge_slave

The vxlan id 10 indicates the VXLAN ID/VNI is indeed 10 as the logical name suggests.

Enable and Manage Service Node and Registration Daemons

Every VTEP must run the registration daemon (vxrd). Typically, every leaf switch acts as a VTEP. A minimum of 1 switch (a switch not already acting as a VTEP) must run the service node daemon (vxsnd). The instructions for enabling these daemons follows.

Enable the Service Node Daemon

The service node daemon (vxsnd) is included in the Cumulus Linux repository as vxfld-vxsnd. The service node daemon can run on any switch running Cumulus Linux as long as that switch is not also a VXLAN VTEP. In this example, enable the service node only on the spine1 switch, then restart the service.

cumulus@spine1:~$ sudo systemctl enable vxsnd.service
cumulus@spine1:~$ sudo systemctl restart vxsnd.service

Enable the Registration Daemon

The registration daemon (vxrd) is included in the Cumulus Linux package as vxfld-vxrd. The registration daemon must run on each VTEP participating in LNV, so you must enable it on every TOR (leaf) switch acting as a VTEP, then restart the vxrd daemon. For example, on leaf1:

cumulus@leaf1:~$ sudo systemctl enable vxrd.service
cumulus@leaf1:~$ sudo systemctl restart vxrd.service

Then enable and restart the vxrd daemon on leaf2:

cumulus@leaf2:~$ sudo systemctl enable vxrd.service
cumulus@leaf2:~$ sudo systemctl restart vxrd.service

Check the Daemon Status

To determine if the daemon is running, use the systemctl status <daemon name>.service command.

For the service node daemon:

cumulus@spine1:~$ sudo systemctl status vxsnd.service
● vxsnd.service - Lightweight Network Virt Discovery Svc and Replicator
   Loaded: loaded (/lib/systemd/system/vxsnd.service; enabled)
   Active: active (running) since Wed 2016-05-11 11:42:55 UTC; 10min ago
 Main PID: 774 (vxsnd)
   CGroup: /system.slice/vxsnd.service
           └─774 /usr/bin/python /usr/bin/vxsnd
 
May 11 11:42:55 cumulus vxsnd[774]: INFO: Starting (pid 774) ...

For the registration daemon:

cumulus@leaf1:~$ sudo systemctl status vxrd.service
● vxrd.service - Lightweight Network Virtualization Peer Discovery Daemon
   Loaded: loaded (/lib/systemd/system/vxrd.service; enabled)
   Active: active (running) since Wed 2016-05-11 11:42:55 UTC; 10min ago
 Main PID: 929 (vxrd)
   CGroup: /system.slice/vxrd.service
           └─929 /usr/bin/python /usr/bin/vxrd
 
May 11 11:42:55 cumulus vxrd[929]: INFO: Starting (pid 929) ...

Configure the Registration Node

The registration node was configured earlier in /etc/network/interfaces in the VXLAN mapping section above; no additional configuration is typically needed. However, if you need to modify the registration node configuration, edit /etc/vxrd.conf.

cumulus@leaf1:~$ sudo nano /etc/vxrd.conf

svcnode_ip = 10.2.1.3

cumulus@leaf2:~$ sudo nano /etc/vxrd.conf

svcnode_ip = 10.2.1.3

cumulus@leaf1:~$ sudo systemctl enable vxrd.service
cumulus@leaf1:~$ sudo systemctl restart vxrd.service

cumulus@leaf2:~$ sudo systemctl enable vxrd.service
cumulus@leaf2:~$ sudo systemctl restart vxrd.service

Configure the Service Node

To configure the service node daemon, edit the /etc/vxsnd.conf configuration file.

cumulus@spine1:~$ sudo nano /etc/vxsnd.conf

The address field is set to the loopback address of the switch running the vxsnd daemon.

svcnode_ip = 10.2.1.3

Enable, then restart the service node daemon for the change to take effect:

cumulus@spine1:~$ sudo systemctl enable vxsnd.service
cumulus@spine1:~$ sudo systemctl restart vxsnd.service

The complete list of options you can configure is listed below:

Advanced LNV Usage

Scale LNV by Load Balancing with Anycast

The above configuration assumes a single service node, which can quickly be overwhelmed by BUM traffic. To load balance BUM traffic across multiple service nodes, use Anycast. Anycast enables BUM traffic to reach the topologically nearest service node instead of overwhelming a single service node.

Enable the Service Node Daemon on Additional Spine Switches

In this example, spine1 already has the service node daemon enabled. Enable it on the spine2 switch, then restart the vxsnd daemon:

cumulus@spine2:~$ sudo systemctl enable vxsnd.service
cumulus@spine2:~$ sudo systemctl restart vxsnd.service

Configure the Anycast Address on All Participating Service Nodes

cumulus@spine1:~$ net add loopback lo ip address 10.10.10.10/32
cumulus@spine1:~$ net pending
cumulus@spine1:~$ net commit

auto lo
iface lo inet loopback
  address 10.2.1.3/32
  address 10.10.10.10/32

cumulus@spine1:~$ ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet 10.2.1.3/32 scope global lo
    inet 10.10.10.10/32 scope global lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever

cumulus@spine2:~$ net add loopback lo ip address 10.10.10.10/32
cumulus@spine2:~$ net pending
cumulus@spine2:~$ net commit

auto lo
iface lo inet loopback
  address 10.2.1.4/32
  address 10.10.10.10/32

cumulus@spine2:~$ ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet 10.2.1.4/32 scope global lo
    inet 10.10.10.10/32 scope global lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever

Configure the Service Node vxsnd.conf File

cumulus@spine1:~$ sudo nano /etc/vxsnd.conf

svcnode_ip = 10.10.10.10
svcnode_peers = 10.2.1.4
src_ip = 10.2.1.3

cumulus@spine1:~$ sudo systemctl enable vxsnd.service
cumulus@spine1:~$ sudo systemctl restart vxsnd.service

cumulus@spine2:~$ sudo nano /etc/vxsnd.conf

svcnode_ip = 10.10.10.10
svcnode_peers = 10.2.1.3
src_ip = 10.2.1.4

cumulus@spine1:~$ sudo systemctl enable vxsnd.service
cumulus@spine1:~$ sudo systemctl restart vxsnd.service

Reconfigure the VTEPs (Leafs) to Use the Anycast Address

cumulus@leaf1:~$ net add loopback lo vxrd-svcnode-ip 10.10.10.10
cumulus@leaf1:~$ net pending
cumulus@leaf1:~$ net commit

auto lo
iface lo inet loopback
  address 10.2.1.1
  vxrd-svcnode-ip 10.10.10.10

cumulus@leaf1:~$ ip -d link show vni-10
35: vni-10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-10 state UNKNOWN mode DEFAULT
    link/ether 46:c6:57:fc:1f:54 brd ff:ff:ff:ff:ff:ff
    vxlan id 10 remote 10.10.10.10 local 10.2.1.1 srcport 32768 61000 dstport 4789 ageing 1800 svcnode 10.10.10.10
    bridge_slave
cumulus@leaf1:~$ ip -d link show vni-2000
39: vni-2000: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-20 state UNKNOWN mode DEFAULT
link/ether 4a:fd:88:c3:fa:df brd ff:ff:ff:ff:ff:ff
vxlan id 2000 remote 10.10.10.10 local 10.2.1.1 srcport 32768 61000 dstport 4789 ageing 1800 svcnode 10.10.10.10
bridge_slave
cumulus@leaf1:~$ ip -d link show vni-30
37: vni-30: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-30 state UNKNOWN mode DEFAULT
link/ether 3e:b3:dc:f3:bd:2b brd ff:ff:ff:ff:ff:ff
vxlan id 30 remote 10.10.10.10 local 10.2.1.1 srcport 32768 61000 dstport 4789 ageing 1800 svcnode 10.10.10.10
bridge_slave

cumulus@leaf1:~$ vxrdctl vxlans
VNI     Local Addr       Svc Node
===     ==========       ========
 10      10.2.1.1        10.2.1.3
 30      10.2.1.1        10.2.1.3
2000      10.2.1.1        10.2.1.3

cumulus@leaf1:~$ net add loopback lo vxrd-svcnode-ip 10.10.10.10
cumulus@leaf1:~$ net pending
cumulus@leaf1:~$ net commit

auto lo
iface lo inet loopback
  address 10.2.1.2
  vxrd-svcnode-ip 10.10.10.10

cumulus@leaf2:~$ ip -d link show vni-10
35: vni-10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-10 state UNKNOWN mode DEFAULT
    link/ether 4e:03:a7:47:a7:9d brd ff:ff:ff:ff:ff:ff
    vxlan id 10 remote 10.10.10.10 local 10.2.1.2 srcport 32768 61000 dstport 4789 ageing 1800 svcnode 10.10.10.10
    bridge_slave
cumulus@leaf2:~$ ip -d link show vni-2000
39: vni-2000: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-20 state UNKNOWN mode DEFAULT
link/ether 72:3a:bd:06:00:b7 brd ff:ff:ff:ff:ff:ff
vxlan id 2000 remote 10.10.10.10 local 10.2.1.2 srcport 32768 61000 dstport 4789 ageing 1800 svcnode 10.10.10.10
bridge_slave
cumulus@leaf2:~$ ip -d link show vni-30
37: vni-30: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-30 state UNKNOWN mode DEFAULT
link/ether 22:65:3f:63:08:bd brd ff:ff:ff:ff:ff:ff
vxlan id 30 remote 10.10.10.10 local 10.2.1.2 srcport 32768 61000 dstport 4789 ageing 1800 svcnode 10.10.10.10
bridge_slave

cumulus@leaf2:~$ vxrdctl vxlans
VNI     Local Addr       Svc Node
===     ==========       ========
 10      10.2.1.2        10.2.1.3
 30      10.2.1.2        10.2.1.3
2000      10.2.1.2        10.2.1.3

Test Connectivity

Repeat the ping tests from the previous section. Here is the table again for reference:

cumulus@server1:~$ ping 10.10.10.2
PING 10.10.10.2 (10.10.10.2) 56(84) bytes of data.
64 bytes from 10.10.10.2: icmp_seq=1 ttl=64 time=5.32 ms
64 bytes from 10.10.10.2: icmp_seq=2 ttl=64 time=0.206 ms
^C
--- 10.10.10.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.206/2.767/5.329/2.562 ms
 
PING 10.10.20.2 (10.10.20.2) 56(84) bytes of data.
64 bytes from 10.10.20.2: icmp_seq=1 ttl=64 time=1.64 ms
64 bytes from 10.10.20.2: icmp_seq=2 ttl=64 time=0.187 ms
^C
--- 10.10.20.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.187/0.914/1.642/0.728 ms
 
cumulus@server1:~$ ping 10.10.30.2
PING 10.10.30.2 (10.10.30.2) 56(84) bytes of data.
64 bytes from 10.10.30.2: icmp_seq=1 ttl=64 time=1.63 ms
64 bytes from 10.10.30.2: icmp_seq=2 ttl=64 time=0.191 ms
^C
--- 10.10.30.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.191/0.913/1.635/0.722 ms

Restart Network Removes vxsnd Anycast IP Address from Loopback Interface

If you have not configured a loopback anycast IP address in the /etc/network/interfaces file, but you have enabled the vxsnd (service node daemon) log to automatically add anycast IP addresses, when you restart networking (with systemctl restart networking), the anycast IP address gets removed from the loopback interface.

To prevent this issue from occurring, specify an anycast IP address for the loopback interface in both the /etc/network/interfaces file and the vxsnd.conf file. This way, in case vxsnd fails, you can withdraw the IP address.

Related Information

• RFC 7348
• Wikipedia - Anycast
• Network virtualization section, Cumulus Linux user guide