Using 40G Mellanox Infiniband single- or dual-port NICs

You do NOT get double the bandwidth on the bonded link
You get RESILIENCE from:
- Failure of one network cable / transceiver
- A single network cable being disconnected on one or both ends
- A single port failure on any one machine
- Failure of a single port on both machines at either end of a single network cable

Quick start - Ethernet mode

Folliwng steps need to be done on BOTHmachines

Package installation

apt install mstflint infiniband-diags You do not need rdma-core or opensm

Put your ports in Ethernet mode

sudo mstconfig query

Output will look like:

Device #1:
----------

Device type:    ConnectX3       
PCI device:     /sys/bus/pci/devices/0000:05:00.0/config

Configurations:                              Next Boot
         SRIOV_EN                            True(1)         
         NUM_OF_VFS                          16              
         LINK_TYPE_P1                        ETH(2)          
         LINK_TYPE_P2                        VPI(3)          
         LOG_BAR_SIZE                        5               
         BOOT_PKEY_P1                        0               
         BOOT_PKEY_P2                        0               
         BOOT_OPTION_ROM_EN_P1               True(1)         
         BOOT_VLAN_EN_P1                     False(0)        
         BOOT_RETRY_CNT_P1                   0               
         LEGACY_BOOT_PROTOCOL_P1             PXE(1)          
         BOOT_VLAN_P1                        0               
         BOOT_OPTION_ROM_EN_P2               True(1)         
         BOOT_VLAN_EN_P2                     False(0)        
         BOOT_RETRY_CNT_P2                   0               
         LEGACY_BOOT_PROTOCOL_P2             PXE(1)          
         BOOT_VLAN_P2                        0               
         IP_VER_P1                           IPv4(0)         
         IP_VER_P2                           IPv4(0)         
         CQ_TIMESTAMP                        True(1)

PCI device: /sys/bus/pci/devices/0000:05:00.0/config : Device name to use with mstconfig is in bold```

Device type: ConnectX3 : ConnectX3 says it is a PCI-Express 3.x capable card

LINK_TYPE_P1 VPI(3) : Says Port 1 is in VPI (Auto) mode LINK_TYPE_P2 ETH(2) : Says Port 2 is in Ethernet mode

On a VPI-capable card, port type can be any of:

1 : Infiniband
2 : Ethernet
3 : VPI (Auto)

Put Port1 in Ethernet mode

mstconfig -d 0000:05:00.0 set LINK_TYPE_P1=2

Put Port2 in Ethernet mode

mstconfig -d 0000:05:00.0 set LINK_TYPE_P2=2

Reboot - mstconfig port type settings will only take effect after a reboot.

Set persistent interface names

After reboot, (even without connecting the cables), you should see two new interfaces listed by ifconfig command. For example:

ifconfig

Output should look like:

ens5p1: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        ether 00:02:c9:3e:ca:b0  txqueuelen 10000  (Ethernet)
        RX packets 2142  bytes 248089 (248.0 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 6121  bytes 5923956 (5.9 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        
ens5: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        ether 00:02:c9:3e:ca:b1  txqueuelen 10000  (Ethernet)
        RX packets 2142  bytes 248089 (248.0 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 6121  bytes 5923956 (5.9 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

The ens5 and ens5p1 interface names may be different

Create a file named /etc/udev/rules.d/70-40g-nic.rules containing the following lines

# Mellanox ConnectX-3 HP 649281-B21 IB FDR/EN 10/40Gb 2P 544QSFP Adapter 656089-001
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:02:c9:3e:ca:b1", ATTR{dev_id}=="0x0", ATTR{type}=="1", NAME="eth40a"

# Mellanox ConnectX-3 HP 649281-B21 IB FDR/EN 10/40Gb 2P 544QSFP Adapter 656089-001
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:02:c9:3e:ca:b0", ATTR{dev_id}=="0x0", ATTR{type}=="1", NAME="eth40b"

IMPORTANT: Change the ATTR{address}=="00:02:c9:3e:ca:b1" and ATTR{address}=="00:02:c9:3e:ca:b0" to reflect your actual MAC addresses. Leave the names as eth40a and eth40b.

If you have only one port, you will only add one (uncommented) line (eth40a)

Reboot again to let the persistent names take effect.

Using a pair of SINGLE port Mellanox VPI 40Gbit NICs

If you have a single-port 40GBit/sec NIC or have only a single cable, you can only use one port on each end (at least at a time). So in such cases, bonding does not make sense.

Setup interface

Edit /etc/network/interfaces/eth40a to contain:

allow-hotplug eth40a
iface eth40g inet static
    hwaddress 00:02:c9:3e:ca:b0
    address 10.30.0.2
    netmask 255.255.255.0
    broadcast 10.30.0.255

Replace 10.30.0.2 with static IP address of MachineA and MachineB respectively. Replace netmask 255.255.255.0 and broadcast 10.30.0.255 based on your IP addresses

Bring up interface

ifdown eth40a; ifup eth40a

Using both ports of a pair of Mellanox VPI 40Gbit NIC

Enable bonding

Add bonding to /etc/modules - load bonding module on reboot
modprobe bonding - until next reboot

Setup interfaces

Edit /etc/network/interfaces/bond0 to contain:

allow-hotplug eth40a
iface eth40a inet manual
    bond-mode active-backup
    bond-master bond0
    pre-up ifconfig eth40a txqueuelen 10000 2>/dev/null || true

allow-hotplug eth40b
iface eth40b inet manual
    bond-mode active-backup
    bond-master bond0
    pre-up ifconfig eth40b txqueuelen 10000 2>/dev/null || true

allow-hotplug bond0
iface bond0 inet static
    bond-mode balance-rr
    use_carrier 1
    bond-slaves eth40a eth40b
    bond-miimon 100
    bond-downdelay 200
    bond-updelay 200
 	address 10.30.0.2
 	netmask 255.255.0.0
	broadcast 10.30.255.255
    pre-down ifconfig eth40a down 2>/dev/null || true
    pre-down ifconfig eth40b down 2>/dev/null || true
    pre-up ifconfig eth40a up 2>/dev/null || true
    pre-up ifconfig eth40b up 2>/dev/null || true

Note that IP address, netmask and broadcast address are ONLY associated with the bond0 address.

Bring up interfaces

ifdown bond0 2</dev/null
ifdown eth40a 2>/dev/null
ifdown eth40b 2>/dev/null
ifup bond0 &
ifup eth40a; ifup eth40b

Check bonding status

cat /proc/net/bonding/bond0

Output should look like:

Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)

Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 200
Down Delay (ms): 200
Peer Notification Delay (ms): 0

Slave Interface: eth40b
MII Status: up
Speed: 40000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:02:c9:3e:ca:b0
Slave queue ID: 0

Quick Start - Infiniband mode

Do the following steps on BOTH machines connected by 40Gbit Infiniband cable.

Package installation

apt install rdma-core opensm ibutils infiniband-diags

Setup interface

Create new file under /etc/network/interfaces.d - e.g. named ib0_4g (the filename is not important) containing:

allow-hotplug ib0
iface ib0 inet static
    address 10.30.0.1
    netmask 255.255.255.0
    broadcast 10.30.0.255

Change the contents of the file to reflect your network (IP address, netmask, broadcast address). Do NOT change the interface name (ib0).

Connect cable between computers

Do this AFTER performing above steps on BOTH computers.

Reboot

Your interface (ib0) should be seen, with the right IP address, netmask etc.

If not, use the command ifconfig -a to see whether interface ib0 was detected at all.

Troubleshooting steps

Use ibstat to see status of interface(s)
cat /sys/class/net/ib0/mode - should show connected or datagram
Check whether opensm service is running: systemctl status opensm. Output should resemble the following:

● opensm.service - LSB: Start opensm subnet manager.
   Loaded: loaded (/etc/init.d/opensm; generated)
   Active: active (running) since Mon 2019-12-30 00:07:32 PST; 1 day 10h ago
     Docs: man:systemd-sysv-generator(8)
  Process: 3060 ExecStart=/etc/init.d/opensm start (code=exited, status=0/SUCCESS)
    Tasks: 39 (limit: 23347)
   CGroup: /system.slice/opensm.service
           └─3110 /usr/sbin/opensm -g 0x0002c903003f02f2 -f /var/log/opensm.0x0002c903003f02f2.log

Dec 30 00:07:32 fili opensm[3060]: Starting opensm on 0x0002c903003f02f2:
Dec 30 00:07:32 fili systemd[1]: Started LSB: Start opensm subnet manager..
Dec 30 00:07:32 fili OpenSM[3110]: /var/log/opensm.0x0002c903003f02f2.log log file opened
Dec 30 00:07:32 fili OpenSM[3107]: /var/log/opensm.0x0202c9fffe3f02f0.log log file opened
Dec 30 00:07:32 fili OpenSM[3107]: OpenSM 3.3.20
Dec 30 00:07:32 fili OpenSM[3110]: OpenSM 3.3.20
Dec 30 00:07:32 fili OpenSM[3107]: Entering DISCOVERING state
Dec 30 00:07:32 fili OpenSM[3110]: Entering DISCOVERING state
Dec 30 00:07:32 fili OpenSM[3107]: Exiting SM
Dec 30 00:07:32 fili OpenSM[3110]: Entering STANDBY state

Checking performance

On both machines, A and B connected by 40Gbit Infiniband cable, having IP addresses IP_A and IP_B on interface ib0respectively, install iperf3: sudo apt install iperf3
On machine A start iperf3 in server mode: iperf3 -B IP_A -i 3 -s - replace IP_A with IP address of interface ib0 on Machine A (sudo / root not required)
On machine B start iperf3 in client mode: iperf3 -B IP_B -i 3 -t 15 -s IP_A - replace IP_A with IP address of interface ib0 on Machine A and replace IP_B with IP address of interface ib0 on machine B (sudo / root not required)

Output on machine B should look like:

Connecting to host 10.30.0.1, port 5201
[  4] local 10.30.0.2 port 51913 connected to 10.30.0.1 port 5201
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-3.00   sec  8.24 GBytes  23.6 Gbits/sec    0   1.81 MBytes       
[  4]   3.00-6.00   sec  8.50 GBytes  24.3 Gbits/sec    0   2.81 MBytes       
[  4]   6.00-9.00   sec  9.58 GBytes  27.4 Gbits/sec    0   2.81 MBytes       
[  4]   9.00-12.00  sec  8.26 GBytes  23.6 Gbits/sec    0   2.81 MBytes       
[  4]  12.00-15.00  sec  8.26 GBytes  23.6 Gbits/sec    0   2.81 MBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-15.00  sec  42.8 GBytes  24.5 Gbits/sec    0             sender
[  4]   0.00-15.00  sec  42.8 GBytes  24.5 Gbits/sec                  receiver

iperf Done.

Troubleshooting and improving performance

Identify your card

lspci | grep Mellanox

Output will look like

81:00.0 Network controller: Mellanox Technologies MT27500 Family [ConnectX-3]

81:00.0 is domain-bus-device number
MT27500 is Mellanox part number
ConnectX-3 indicates card supports PCI-Express 3 - actual PCI-Express version also depends on PCI-Express capabilities of your motherboard

Get additional details on your card

Use domain-bus-device number obtained above

lspci -v -s 81:00.0

Output will look like:

81:00.0 Network controller: Mellanox Technologies MT27500 Family [ConnectX-3]
	Subsystem: Hewlett-Packard Company InfiniBand FDR/EN 10/40Gb Dual Port 544QSFP Adapter
	Physical Slot: 5
	Flags: bus master, fast devsel, latency 0, IRQ 47, NUMA node 1
	Memory at ec100000 (64-bit, non-prefetchable) [size=1M]
	Memory at 3800fe000000 (64-bit, prefetchable) [size=32M]
	Expansion ROM at ec000000 [disabled] [size=1M]
	Capabilities: <access denied>
	Kernel driver in use: mlx4_core
	Kernel modules: mlx4_core

Subsystem: Hewlett-Packard Company InfiniBand FDR/EN 10/40Gb Dual Port 544QSFP Adapter gives further OEM details

Get current PCI-Express version and width used

Use domain-bus-device number obtained above

sudo lspci -vv -s 81:00.0 | grep LnkSta:

Output will look like:

LnkSta: Speed 8GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-

Speed 8GT/s : 8 GT/s indicates PCI-Express version 3.x is being currently used for that slot
Width x8 : indicates logical width is x8 (8 lanes)

PCI-Express speeds and maximum possible bandwidth for network link

PCI-E version	Per lane GT/sec	Per lane MBytes/sec
1.x	2.5 GT/sec	250 MBytes/sec
2.x	5 GT/sec	500 MBytes/sec
3.x	8 GT/sec	985 MBytes/sec
4.x	16 GT/sec	1.97 GBytes/sec

PCI-E Version	Per lane GT/sec	Physical	Logical	Bandwidth MBytes/sec
2.x	5 GT/sec	x8	x1	250 MBytes/sec
2.x	5 GT/sec	x8	x4	1 GBytes/sec
2.x	5 GT/sec	x8	x8	2 GBytes/sec
2.x	5 GT/sec	x16	x1	250 MBytes/sec
2.x	5 GT/sec	x16	x4	1 GBytes/sec
2.x	5 GT/sec	x16	x8	2 GBytes/sec
3.x	8 GT/sec	x8	x1	985 MBytes/sec
3.x	8 GT/sec	x8	x4	3.94 GBytes/sec
3.x	8 GT/sec	x8	x8	7.88 GBytes/sec
3.x	8 GT/sec	x16	x1	985 MBytes/sec
3.x	8 GT/sec	x16	x4	3.94 GBytes/sec
3.x	8 GT/sec	x16	x8	7.88 GBytes/sec

Notes:

Physical width will never be smaller than physical width of PCI-Express device (x8 in this case)
Logical width will never be larger than physical width
Logical width will never be larger than actual width of PCI-Express device lane width (x8 in this case)

Limiting factors for maximum bandwidth of network link

PCI-Express version
Logical slot width - may depend on configurable settings in the BIOS for your motherboard
Maximum bandwidth for network link will be LESSER of maximum bandwidth for each of the connected machines as explored above

sysctl settings for TCP/IP stack

Put etc/sysctl.d/60-infiniband.conf under /etc/sysctl.d and reboot

Contents of etc/sysctl.d/60-infiniband.conf

# For Mellanox MT27500 ConnextX-3 (HP InfiniBand FDR/EN 10/40Gb Dual Port 544QSFP)
# Settings from https://furneaux.ca/wiki/IPoIB#Kernel_Tuning
# Originally settings from Mellanox:
#   https://community.mellanox.com/s/article/linux-sysctl-tuning
net.ipv4.tcp_timestamps=0
net.ipv4.tcp_sack=1
net.core.netdev_max_backlog=250000
net.core.rmem_max=4194304
net.core.wmem_max=4194304
net.core.rmem_default=4194304
net.core.wmem_default=4194304
net.core.optmem_max=4194304
net.ipv4.tcp_low_latency=1
net.ipv4.tcp_adv_win_scale=1
net.ipv4.tcp_rmem=4096 87380 4194304
net.ipv4.tcp_wmem=4096 65536 4194304

Interface connected state and MTU

Only applicable to using Infiniband mode

Put etc/systemd/system/setup_ib0.service under etc/systemd/system/
Run systemctl enable setup_ib0.service and reboot

Contents of etc/systemd/system/setup_ib0.service

[Unit]
Description=Setup ib0
After=sys-subsystem-net-devices-ib0.device

[Service]
Type=oneshot
ExecStart=/bin/echo connected > /sys/class/net/ib0/mode
ExecStart=/sbin/ifconfig ib0 mtu 65520

Run iperf3 with larger number of threads (software bottleneck in iperf3)

On machine A start iperf3 in server mode: iperf3 -B IP_A -i 3 -P2 -s - replace IP_A with IP address of interface ib0 on Machine A (sudo / root not required)
On machine B start iperf3 in client mode: iperf3 -B IP_B -i 3 -t 15 -P2 -s IP_A - replace IP_A with IP address of interface ib0 on Machine A and replace IP_B with IP address of interface ib0 on machine B (sudo / root not required)

On each side, try -P2, -P4 and -P8 to see what extracts the maximum bandwidth from the link. For me I got the maximum with -P4.

Run multiple instances of iperf3

On each machine start iperf3 (in server and client modes respectively) adding the -p <port_num> option to choose a port different from the iperf3 default 5201

Name		Name	Last commit message	Last commit date
Latest commit History 36 Commits
etc		etc
DualPort_Ethernet_Link.png		DualPort_Ethernet_Link.png
LICENSE		LICENSE
README.md		README.md
README.pdf		README.pdf
SinglePort_Ethernet_Link.png		SinglePort_Ethernet_Link.png

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Using 40G Mellanox Infiniband single- or dual-port NICs

Table of Contents

Operating environment

Should I use Infiniband mode or Ethernet mode?

Advantages of Infiniband

Disadvantages of Infiniband

Advantages of Ethernet mode

Using both ports of a dual-port VPI NIC - what do I get?

Quick start - Ethernet mode

Package installation

Put your ports in Ethernet mode

Put Port1 in Ethernet mode

Put Port2 in Ethernet mode

Set persistent interface names

Using a pair of SINGLE port Mellanox VPI 40Gbit NICs

Setup interface

Bring up interface

Using both ports of a pair of Mellanox VPI 40Gbit NIC

Enable bonding

Setup interfaces

Bring up interfaces

Check bonding status

Quick Start - Infiniband mode

Package installation

Setup interface

Connect cable between computers

Reboot

Troubleshooting steps

Checking performance

Troubleshooting and improving performance

Identify your card

Get additional details on your card

Get current PCI-Express version and width used

PCI-Express speeds and maximum possible bandwidth for network link

Limiting factors for maximum bandwidth of network link

sysctl settings for TCP/IP stack

Interface connected state and MTU

Run iperf3 with larger number of threads (software bottleneck in iperf3)

Run multiple instances of iperf3

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