Load Balancing on Mellanox Switches

In this test case the goal is to create a simple load balancer using a reverse LAG port. The idea is to have one input port which is then mirrored to a logical LAG port and at the other end of the LAG port is a number of security sensors.

Version Info

    mellanox.lan [standalone: master] # show version
    Product name:      Onyx
    Product release:   3.8.2004
    Build ID:          #1-dev
    Build date:        2019-09-23 14:19:47
    Target arch:       x86_64
    Target hw:         x86_64
    Built by:          jenkins@7ae5fd122b61
    Version summary:   X86_64 3.8.2004 2019-09-23 14:19:47 x86_64

    Product model:     x86onie
    Host ID:           B8599FD560BE
    System serial num: MT1940T00588
    System UUID:       5f4c5ed2-e60b-11e9-8000-b8599f7f6f40

    Uptime:            17h 27m 36.480s
    CPU load averages: 3.17 / 3.17 / 3.11
    Number of CPUs:    4
    System memory:     2738 MB used / 5065 MB free / 7803 MB total
    Swap:              0 MB used / 0 MB free / 0 MB total

Connect to the Console Port and Management Ethernet Port

Plug in both the management Ethernet cable and the serial cable. The console port is the bottom port and the ethernet management port is the top port.

I had to plug the console cable into a specific USB slot on the server. It didn't work in the first one I tried. See picture below.

This likely has nothing to do with the Mellanox switch itself, but as a note for those that come after you may want to try different USB ports if you find you aren't getting output on the first one you try and are confident you have the correct settings.

I used the following console configuration:

    Baud Rate: 115200
    Data Bits: 8
    Stop Bits: 1
    Parity: None
    Flow Control: None

Update to Latest Version of MLNX-OS

I pulled updates here
The system uses a web server target for updates. I had Apache running on a RHEL 8 box.
Download the update file and then upload it to your web server's root directory.
On the switch itself (over a console port) do the following:
```
switch > enable
switch # configure terminal
switch (config) # show images

# Delete the old image if it exists. It will be under
# "Images available to be installed"

switch (config) # image delete <old_image>
```
1. Download the new image from your web server with
  
  mellanox.lan [standalone: master] # image fetch http://rhel8.lan/onyx-X86_64-3.8.2004.img 100.0% [################################################################################################################################################################################################################################################################]

Next install the updated OS with:

mellanox.lan [standalone: master] # image install onyx-X86_64-3.8.2004.img location 2 progress track verify check-sig
Step 1 of 4: Verify Image
100.0%  [#################################################################]
Step 2 of 4: Uncompress Image
100.0%  [#################################################################]
Step 3 of 4: Create Filesystems
100.0%  [#################################################################]
Step 4 of 4: Extract Image
98.6%  [################################################################ ]
100.0%  [#################################################################]

Now set the switch to load from the new operating system and reload:

mellanox.lan [standalone: master] # image boot next
mellanox.lan [standalone: master] # reload

Physical Configuration

I used the following port configuration:

1, 1Gb/s copper SFP (Eth1/1) for input
2, 1Gb/s copper SFPs (Ethernet 1/1/5/Ethernet 1/1/9) and 1, 1Gb/s, fiber SFP (Ethernet 1/1/12) for output

I used the following optics:

Connect the input port to port 1.

I connected my output ports in the following way:

Bringing the Interfaces Up

Mellanox does not perform testing with 3rd party NICs. During testing we found that autonegotiation of speed will not work on standard Dell SFPs. Use the below command on each interface to set the speed manually:

    mellanox.lan [standalone: master] (config interface ethernet 1/1) # speed 1G

Configure the LAG

Initial Configuration

    mellanox.lan [standalone: master] (config) # port-channel load-balance ethernet source-destination-mac source-destination-ip source-destination-port symmetric
    mellanox.lan [standalone: master] (config) # interface port-channel 1
    mellanox.lan [standalone: master] (config interface port-channel 1) # switchport mode hybrid
    mellanox.lan [standalone: master] (config interface port-channel 1) # description load balance group
    mellanox.lan [standalone: master] (config interface port-channel 1) # no shut
    mellanox.lan [standalone: master] (config interface port-channel 1) # mtu 9000 force
    mellanox.lan [standalone: master] (config interface port-channel 1) # exit
    mellanox.lan [standalone: master] (config) # interface ethernet 1/5 switchport mode hybrid
    mellanox.lan [standalone: master] (config) # interface ethernet 1/9 switchport mode hybrid
    mellanox.lan [standalone: master] (config) # interface ethernet 1/12 switchport mode hybrid
    mellanox.lan [standalone: master] (config) # interface ethernet 1/1 switchport mode hybrid
    mellanox.lan [standalone: master] (config) # interface ethernet 1/1 mtu 9000 force
    mellanox.lan [standalone: master] (config) # interface ethernet 1/5 mtu 9000 force
    mellanox.lan [standalone: master] (config) # interface ethernet 1/9 mtu 9000 force
    mellanox.lan [standalone: master] (config) # interface ethernet 1/12 mtu 9000 force
    mellanox.lan [standalone: master] (config) # interface ethernet 1/5 channel-group 1 mode on
    mellanox.lan [standalone: master] (config) # interface ethernet 1/9 channel-group 1 mode on
    mellanox.lan [standalone: master] (config) # interface ethernet 1/12 channel-group 1 mode on

Problem Using Port Mirroring

Originally my plan was to use a mirror port to send all the traffic from port 1 to our LAG interface. In contrast to OS10, MLNX-OS will not allow you to do this. The problem is that MLNX-OS will not allow you to create a mirror session from interface 1 to the LAG port which prevents this configuration from working. Moreover you cannot access the Linux command line to use a utility like tc to perform the config either.

Configure OpenFlow

Instead of using port mirroring to send the traffic from interface one we can instead use a static OpenFlow configuration to redirect the traffic.

    mellanox.lan [standalone: master] (config) # interface ethernet 1/1 openflow mode hybrid
    mellanox.lan [standalone: master] (config) # interface port-channel 1 openflow mode hybrid
    mellanox.lan [standalone: master] (config) # openflow add-flows 1000 priority=50,in_port=Eth1/1,actions=output:Po1

Findings

The Mellanox SN2010 works correctly and will appropriately load balance full sessions across each member of the LAG. See below for screenshots.