Get started with 40GbE SDN with Microsoft Azure SONiC for under $1K

Arista 7050QX 32 Rack
Arista 7050QX 32 Rack

Ever want to try high-speed SDN without spending $10,000 or more on a switch? This guide will show you how to take a <$1000 40GbE Arista switch and load Microsoft Azure SONiC (Software for Open Networking in the Cloud) on it. This post originated from a discussion on this in the STH forums here. You can find more in this project via GitHub here. You can get the switch we used for under $1000 on eBay. The Arista 7050QX-32 is entering a phase where it will no longer receive firmware patches making it a great SDN test switch. This guide will get you up and running for those that want to try SONiC.

Azure SONiC on the Arista 7050QX-32


I finally got to spend some quality time with my Arista 7050QX-32 and Azure SONiC. SONiC, an open source network operating system sponsored by Microsoft. Out of the box without any configuration whatsoever, has BGP running on all of the interfaces. This is intended to allow Layer 3 native IP networking for each of the hosts and their containers, significantly simplifying networking without the typical Layer 2 container networking overlays. After installing and configuring my hosts for BGP, I can get TCP performance at line rate between containers on different hosts without tuning much (although the MTU is 9000 and that helps a lot).

$ docker run -it --name mycentos centos bash
[root@1e24805a735c /]# yum install iperf

[root@1e24805a735c]# iperf -c

Client connecting to, TCP port 5001
TCP window size: 2.00 MByte (default)

[ 3] local port 34042 connected with port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 24.7 GBytes 21.2 Gbits/sec

The same CentOS Docker image is running on in iperf server mode. The bare metal here are dual e5-2670 machines using the awesome Intel s2600cp2 board.

[root@1e24805a735c]# iperf -c -P 4

Client connecting to, TCP port 5001
TCP window size: 2.00 MByte (default)

[ 6] local port 34050 connected with port 5001
[ 4] local port 34046 connected with port 5001
[ 3] local port 34044 connected with port 5001
[ 5] local port 34048 connected with port 5001
[ ID] Interval Transfer Bandwidth
[ 6] 0.0-10.0 sec 10.8 GBytes 9.27 Gbits/sec
[ 4] 0.0-10.0 sec 10.6 GBytes 9.12 Gbits/sec
[ 3] 0.0-10.0 sec 10.6 GBytes 9.13 Gbits/sec
[ 5] 0.0-10.0 sec 11.2 GBytes 9.60 Gbits/sec
[SUM] 0.0-10.0 sec 43.2 GBytes 37.1 Gbits/sec

Layer 3 networking has the advantage of fewer proprietary extensions that enable large cloud-like fabrics while allowing dynamic config via standard routing software and isolating tenants. That’s the sales pitch anyways, in buzzword lingo. Used, it costs about as much as a decent Xeon and all the wiring cost a little more than gigabit network.

Here are my experiences installing SONiC it.


Get into Aboot from a Serial Line

I recommend kermit, it makes me smile, because I’m usually booting some random hardware for the first time when I run it. There was a blue Cisco style rollover cable that came with my switch.

root@host:~# kermit
(/home/admin/) C-Kermit>set line /dev/ttyS0
(/home/admin/) C-Kermit>set speed 9600
(/home/admin/) C-Kermit>conn

Power the switch and hit ctrl-c at the prompt. You should have an Aboot shell at this point (which is a busybox env).

Copy the SONiC Distribution for Arista

Get a switch binary from here:

I put this on a USB stick and inserted into the switch. Aboot will mount the USB as /mnt/usb1 and the flash as /mnt/flash.

Backup the existing EOS software onto the USB, it will be erased by the SONiC install, there will be no backup saved on the switch.

Aboot:~# cd /mnt/flash
Aboot:~# cp -a ./* /mnt/usb1/
Aboot:~# cp /mnt/usb1/sonic-aboot-broadcom.swi .

Boot SONiC

Aboot:~# boot /mnt/flash/sonic-aboot-broadcom.swi

This erases the flash and installs SONiC onto it. You clear the flash again and boot EOS by following the Aboot instructions here:
EOS Section 6.5: Aboot Shell – Arista

I used fullrecover and boot EOS-*.swi several times. The EOS, boot-config and startup-config can be restored from the USB drive, like this:

Abool# cd /mnt/flash
Aboot# fullrecover
All data on /mnt/flash will be erased; type "yes" and press Enter to proceed,
or just press Enter to cancel: yes
Erasing /mnt/flash
Aboot# cp /mnt/usb1/EOS-4.14.5FX.3.swi .
Aboot# cp /mnt/usb1/startup-config startup-config
Aboot# cp /mnt/usb1/boot-config boot-config
Aboot# reboot

Login to SONiC

arista login: admin
Password: YourPaSsWoRd

Last login: Tue Oct 31 04:10:18 UTC 2017 from on pts/9
Linux arista 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u2 (2015-12-19) x86_64
You are on
  ____   ___  _   _ _  ____
 / ___| / _ \| \ | (_)/ ___|
 \___ \| | | |  \| | | |
  ___) | |_| | |\  | | |___
 |____/ \___/|_| \_|_|\____|

-- Software for Open Networking in the Cloud --

Unauthorized access and/or use are prohibited.
All access and/or use are subject to monitoring.

admin@arista:~$ sudo -i bash

The eth0 device is the gigabit management interface, it will start dhclient to get the address. I usually setup my /etc/dhcp/dhcpd.conf to hand out addresses based on the MAC address (use ip addr show eth0 in the serial line

root@router:~# grep 'host arista' -A 4 /etc/dhcp/dhcpd.conf
host arista {
  option host-name "arista";
  hardware ethernet 44:4c:a8:12:87:c6;

After eth0 is configured, you can ssh admin@ and skip the slow tty.

Fix the Loud Fans

SONiC does not dynamically adjust the fans on this switch. It puts them at high speed, so it will be very annoying if the switch is anywhere close to you. You can read the sensors and adjust the fans manually.

root@arista:~# echo 120 > /sys/devices/platform/sb800-fans/hwmon/hwmon1/pwm1
root@arista:~# echo 120 > /sys/devices/platform/sb800-fans/hwmon/hwmon1/pwm2
root@arista:~# echo 120 > /sys/devices/platform/sb800-fans/hwmon/hwmon1/pwm3
root@arista:~# echo 120 > /sys/devices/platform/sb800-fans/hwmon/hwmon1/pwm4
root@arista:~# cat /sys/devices/platform/sb800-fans/hwmon/hwmon1/fan1_input

The command show is the cli way of examining the state of the switch:

root@arista:~# show environment
Command: sudo sensors
Adapter: PCI adapter
Cpu temp sensor: +36.0 C (high = +70.0 C)

Adapter: ISA adapter
fan1: 12611 RPM
fan2: 12611 RPM
fan3: 12611 RPM
fan4: 12381 RPM

There is a fancontrol daemon, but it needs configuration via pwmconfig. This configuration needs to be done in the pmon container.

root@arista:~# docker exec -it pmon bash
root@arista:~# pwmconfig

The pwmconfig will allow you to choose which temp sensor devices control which fans. The fancontrol daemon doesn’t quite agree with pwmconfig for some temp sensors, so I used the CPU temperature to control the fan speed, since it is the highest value.

Test it:

root@arista:~# VERBOSE=1 /etc/init.d/fancontrol start

It should start automatically on boot by via systemd when it exists in the platform config /usr/share/sonic/device/x86_64-arista_7050_qx32/fancontrol. Exit the pmon container and copy the fancontrol file to that location.

root@arista:~# docker cp pmon:/etc/fancontrol /usr/share/sonic/device/x86_64-arista_7050_qx32/fancontrol
root@arista:~# cat /usr/share/sonic/device/x86_64-arista_7050_qx32/fancontrol
DEVPATH=hwmon0=devices/pci0000:00/0000:00:18.3 hwmon1=devices/platform/sb800-fans
DEVNAME=hwmon0=k10temp hwmon1=fans
FCTEMPS=hwmon1/pwm4=hwmon0/device/temp1_input hwmon1/pwm3=hwmon0/device/temp1_input hwmon1/pwm2=hwmon0/device/temp1_input hwmon1/pwm1=hwmon0/device/temp1_input
FCFANS=hwmon1/pwm4=hwmon1/fan4_input hwmon1/pwm3=hwmon1/fan3_input hwmon1/pwm2=hwmon1/fan2_input hwmon1/pwm1=hwmon1/fan1_input
MINTEMP=hwmon1/pwm4=20 hwmon1/pwm3=20 hwmon1/pwm2=20 hwmon1/pwm1=20
MAXTEMP=hwmon1/pwm4=60 hwmon1/pwm3=60 hwmon1/pwm2=60 hwmon1/pwm1=60
MINSTART=hwmon1/pwm4=150 hwmon1/pwm3=150 hwmon1/pwm2=150 hwmon1/pwm1=150
MINSTOP=hwmon1/pwm4=0 hwmon1/pwm3=0 hwmon1/pwm2=0 hwmon1/pwm1=0

Exploring SONiC

The architecture of SONiC is described here:
Architecture · Azure/SONiC Wiki · GitHub

It is a collection of daemons which use a Redis database to communicate and persist configuration. You can use redis-cli to examine the database and the activity of the daemons. For example, this shows what the daemons are doing:

root@arista:~# redis-cli psubscribe '*'
1) "psubscribe"
2) "*"
3) (integer) 1
1) "pmessage"
2) "*"
3) "__keyspace@2__:COUNTERS:1000000000002"
4) "hset"
1) "pmessage"
2) "*"
3) "__keyevent@2__:hset"
4) "COUNTERS:1000000000002"
1) "pmessage"
2) "*"

The file /etc/sonic/config_db.json contains the startup configuration. The Redis database is populated from this and the daemons configure the switch by using Redis operations. OpenSwitch also has foundations for a Redis based configuration, but it seems a bit behind, whereas Microsoft is building a new SONiC version continuously here:
Jenkins buildimage-brcm-aboot-all.

The daemons in SONiC are inside Docker containers. For example, the BGP container looks like this:

root@arista:~# docker ps --format 'table {{.Names}}\t{{.Command}}\t{{.Image}}'
NAMES               COMMAND                  IMAGE
snmp                "/usr/bin/supervisord"   docker-snmp-sv2:latest
dhcp_relay          "/usr/bin/docker_init"   docker-dhcp-relay:latest
syncd               "/usr/bin/supervisord"   docker-syncd-brcm:latest
swss                "/usr/bin/supervisord"   docker-orchagent-brcm:latest
teamd               "/usr/bin/supervisord"   docker-teamd:latest
bgp                 "/usr/bin/supervisord"   docker-fpm-quagga:latest
lldp                "/usr/bin/supervisord"   docker-lldp-sv2:latest
pmon                "/usr/bin/supervisord"   docker-platform-monitor:latest
database            "/usr/bin/supervisord"   docker-database:latest

root@arista:~# docker exec -it bgp bash
root@arista:~# ps ax
1 ? Ss+ 2:16 /usr/bin/python /usr/bin/supervisord
29 ? S 0:00 python /usr/bin/bgpcfgd
33 ? Sl 0:03 /usr/sbin/rsyslogd -n
38 ? S 0:02 /usr/lib/quagga/zebra -A
40 ? S 1:26 /usr/lib/quagga/bgpd -A -F
42 ? Sl 0:00 fpmsyncd
180 ? Ss 0:00 bash
184 ? R+ 0:00 ps ax

root@arista:~# head -30 /etc/quagga/bgpd.conf
! =========== Managed by sonic-cfggen DO NOT edit manually! ====================
! generated by templates/quagga/bgpd.conf.j2 with config DB data
! file: bgpd.conf
hostname switch1
password zebra
log syslog informational
log facility local4
! enable password !
! bgp multiple-instance
route-map FROM_BGP_SPEAKER_V4 permit 10
route-map TO_BGP_SPEAKER_V4 deny 10
router bgp 65100
  bgp log-neighbor-changes
  bgp bestpath as-path multipath-relax
  no bgp default ipv4-unicast
  bgp router-id


Set up the IP Addresses

As it is installed in build #270, SONiC defines each of the 32 ports with a with an EthernetX device and a 10.0.0.Y address on port N range 1→32, where X = (N-1) * 4 and Y = (N-1) * 2. These are the IP addresses assigned to ports 17 and 18:

root@arista:~# ip addr show | egrep 'inet.*Ethernet6[48]'
inet brd scope global Ethernet64
inet brd scope global Ethernet68

The first 16 ports use Internal BGP, the second 16 ports are External BGP. Since External BGP distributes the routes across the cluster and I am not connecting BGP to the Internet, I used the ports 17→32. I plan on creating a Layer 2 LANs with the first 16 ports.

The addresses assigned to the hosts are:

  • host → switch port 17
  • host → switch port 18

Since the layer 2 network set up using this config is confined to the link between the switch and the port, the host has to route through the switch in order to connect with the other ports otherwise any IP address other than the link pair will try to route to the wrong network. I did this by setting up my router as the default-gateway, which propagates default route through the switch to the hosts. My initial 6 host config looks like this:

  • CentOS 7 Server → switch port 17
  • Fedora 26 Workstation → switch port 19
  • CentOS 7 Server → switch port 21
  • Fedora 26 Workstation → switch port 23
  • Fedora 26 Router → switch port 25
  • CentOS 7 Server → switch port 27

Install quagga and start zebra.

root@router:~# yum install quagga
root@router:~# systemctl start zebra

My 40gbe devices are named fo0 and fo1.

root@router:~# vtysh
router# config term
router(config)# log file /var/log/quagga/quagga.log
router(config)# interface fo0
router(config-if)# ip address
router(config-if)# no shutdown
router(config-if)# end
router# write
Building Configuration...
Configuration saved to /etc/quagga/zebra.conf

You should be able to ping from the host to, which is port 25 on the switch, in this case, my Fedora 26 Router.

root@router:~# ping -c 3
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=64 time=0.316 ms
64 bytes from icmp_seq=2 ttl=64 time=0.188 ms
64 bytes from icmp_seq=3 ttl=64 time=0.156 ms

--- ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1999ms
rtt min/avg/max/mdev = 0.059/0.062/0.066/0.003 ms

One other thing I did on the router was route the range through the switch:

root@router:~# vtysh
router# config term
router(config)# ip route fo0
router(config-if)# end
router# write

Repeat the above for each host connected, except for the last line.

Set up BGP Routing

Each of my hosts has a docker0 device on it using a unique IP address range. BGP is going to distribute the routes for the docker0 bridge across the cluster. This is the Docker dameon config file that causes docker to create a
default bridge at

root@host:~# cat /etc/docker/daemon.json
    "dns": [""],
    "iptables": false,
    "ip-forward": false,
    "ip-masq": false,
    "storage-driver": "btrfs",
    "bip": "",
    "fixed-cidr": "",
    "mtu": 1500
root@host:~# systemctl start docker
root@host:~# brctl show
bridge name     bridge id               STP enabled     interfaces
docker0         8000.0242deb9f0e5       no
root@host:~# ip -4 addr show dev docker0
8: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
    inet scope global docker0
       valid_lft forever preferred_lft forever

The DNS entry is a caching named on the router. I set up a loopback device with this IP address and distributed it with BGP.

root@router:~# cat /etc/sysconfig/network-scripts/ifcfg-lo:1

Here is the /etc/quagga/bgpd.conf for the above Docker bridge on the CentOS 7 server plugged into port 21.

root@host:~# cat /etc/quagga/bgpd.conf
hostname myhost
password zebra
log file /var/log/quagga/bgp.log

router bgp 64005
  bgp router-id
  neighbor remote-as 65100

Start bgpd to communicate with the BGP running on switch.

root@host:~# systemctl start bgpd

The 64005 AS number above is unique for each port from 17 → 32. These are configured be on the switch in the BGP container in /etc/quagga/bgpd.conf via the Redis database.

  • port 17 = AS 64001 to switch AS 65100
  • port 19 = AS 64003 to switch AS 65100
  • port 21 = AS 64005 to switch AS 65100
  • port 23 = AS 64007 to switch AS 65100
  • port 25 = AS 64009 to switch AS 65100
  • port 27 = AS 64011 to switch AS 65100

Sinced the above host is in port 21, the AS number is 64005 (AS is a BGP acronym for Autonomous system). After starting bgpd on each of the hosts, you should see the routes populated by BGP with the protocol zebra. On the switch it shows this:

root@arista:/# ip route show | grep zebra
ip route show | grep zebra
default via dev Ethernet96  proto zebra  src via dev Ethernet64  proto zebra  src via dev Ethernet72  proto zebra  src via dev Ethernet80  proto zebra  src via dev Ethernet88  proto zebra  src via dev Ethernet96  proto zebra  src via dev Ethernet96  proto zebra  src

All the hosts are set up the same, except for the router. The router has this in the /etc/quagga/bgpd.conf:

hostname router
password zebra
log file /var/log/quagga/bgp.log

router bgp 64009
  bgp router-id
  neighbor remote-as 65100
  neighbor default-originate

Note the “default-originate” line. This propagates the default route to the hosts and the switch.

I also block the BGP port from the internet side:

root@host:~# iptables -A INPUT -i te0 -p udp -m udp --dport 179 -j DROP
root@host:~# iptables -A INPUT -i te0 -p tcp -m tcp --dport 179 -j DROP

Set up Layer 2 Vlans

In order to use a port in normal ethernet mode, a Vlan has to be created and ports need to be added to it. There is no DEFAULT_VLAN.

The location of the SONiC config file is on the switch here:

When the switch boots, it loads this into the Redis database. The switch daemons that are running in Docker monitor the database through pub/sub subscriptions and update the operating state. The VLAN part that becomes the Debian ifupdown configuration uses a Python templating language called Jinja2.

To add a Vlan, there are two components of the json file that need to be updated, the “VLAN” field and the “VLAN_INTERFACE” field. The following is the first 10 ports and the last two ports (1→10, 31→32) configured for the Vlan1000. I am using the network for this VLAN.

    "VLAN": {
        "Vlan1000": {
            "members": [
            "vlanid": "1000"
        "Vlan1000|": {}

The template interfaces.j2 generates the file /etc/network/interfaces from the above json, which looks like this:

root@arista:/# tail -15 /etc/network/interfaces
allow-hotplug Ethernet124
iface Ethernet124 inet manual
    pre-up ifconfig Ethernet124 up mtu 9100
    post-up brctl addif Vlan1000 Ethernet124 || true
    post-down ifconfig Ethernet124 down
# Vlan interfaces
auto Vlan1000
iface Vlan1000 inet static
    bridge_ports none
    hwaddress ether 44:4c:a8:12:87:c6

After startup, you can verify that the ports configured are indeed in the Vlan1000 bridge:

root@arista:/# brctl show
bridge name     bridge id               STP enabled     interfaces
Vlan1000        8000.444ca81287c6       no              Ethernet0
docker0         8000.0242d26920e5       no

I also removed these ports from the other sections of the configuration file, specifically the “BGP_NEIGHBOR”, “DEVICE_NEIGHBOR”, and “INTERFACE”.

Since my router is populating the default route for the BGP network, I also set the management address to be static, otherwise the DHCP default route overrides the BGP. This configured in the “MGMT_INTERFACE” section of the json file:

        "eth0|": {}

Appendix A: Config Files

You can find these config files on the Github page.

My SONiC config file in its entirety:


Config files for my Fedora 26 router on port 25:



Config files for my CentOS 7 server on port 21:





  1. I’m wondering if these would work in an S2D config using RoCE from the hosts.

    Do you know if they’d be capable of working in this type of config? I would assume so, given SonicOS is supposed to be what MS runs Azure on top of, but would be good to get clarity on this.



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