Quanta LB4M 48-Port Gigabit Switch Discussion

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Active Member
Jan 28, 2016
Bavaria / Germany
Ah, ok .... never heard but looks interesting.

Guess it has the snmp oid`s for the lb4m preconfigured ?
So it might be possible to extract them from the sources and/or wireshark while it runs ...

Jonathan Woytek

New Member
Nov 26, 2016
Hello all. I have seen a lot of folks posting some questions here about configurations on the LB4M. I've run through a couple of configuration scenarios and thought I'd maybe contribute some of them back to this thread (which helped me immensely as I got started with this thing).

The LB4M has been a good switch for me so far, deployed in a growing home lab setup. I run the firmware. I generally eschew web configuration interfaces for network equipment, so it has not bothered me one bit to not have on on here. The only physical modification I've made was to replace every fan in the power supplies and case with the Noctua 40mm fans, performing the pin mod on the connectors for the power supply. I did not modify the connections for the four-pin case fan connectors, so they don't supply correct tach info back to the system board, but I'm OK with that in my application.

A configuration example:
My current test configuration with some VLANs and interfaces configured to use them either as access ports or trunked interfaces (NOTE: on the LB4m, every interface that doesn't have a pvid defined can be thought of as pvid 1; On this switch, I'm using VLAN 1 as management and temporary uplink to a cable modem, so anything that needs to talk to the cable modem is left in VLAN 1):

! Create vlans
vlan database
vlan 10,15,20,30,100,200,210
vlan name 10 "mgmt"
vlan name 15 "vmgmt"
vlan name 20 "intsvc"
vlan name 30 "extsvc"
vlan name 100 "storage"
vlan name 200 "home"
vlan name 210 "vpn"
! This interface is an unused uplink interface
interface 0/1
vlan participation include 10
! This interface is the primary uplink interface. 
! Stuff in the "home" vlan and "mgmt" vlan need to talk over the internet right now.
! This will be removed later when the cable modem runs through the new router.
interface 0/2
vlan participation include 10,200
! 0/3-0/8 all look like this. They are access ports for management interfaces. 
! They are currently also implicit members of vlan 1 so that they can talk to 
! the internet. This is only for setup and will be removed in the near future.
! HINT: Configure a range of interfaces like this: interface 0/3-0/8
interface 0/3
spanning-tree edgeport
vlan pvid 10
vlan participation include 10
interface 0/4
spanning-tree edgeport
vlan pvid 10
vlan participation include 10
! ... these all look the same through 0/8 ...
! 0/9-0/12 and 0/13-0/16 are two four-port LAG connections
! These are excluded from all vlans on purpose
interface 0/9
vlan participation exclude 1,10,15,20,30,100,200,210
interface 0/10
vlan participation exclude 1,10,15,20,30,100,200,210
interface 0/11
vlan participation exclude 1,10,15,20,30,100,200,210
interface 0/12
vlan participation exclude 1,10,15,20,30,100,200,210
! ... 0/13-0/16 look the same ...
! OK, use case for 0/37 -0/48 is that these ports connect to existing
! devices in the home and are generally assumed to be not vlan-aware.
! These ports are configured as access ports with access to vlan 1 in order
! to get out on the internet. Again, that will change a little once the router 
! is in place. If someone walked into the house and wanted a network port,
! they could plug into here, get a config via DHCP, etc....
interface 0/37
spanning-tree edgeport
vlan pvid 200
vlan acceptframe admituntaggedonly
vlan ingressfilter
vlan participation include 200
! ... 0/38-0/48 are identical ...
! 0/49-0/50 are the two 10G SFP+ ports. These are currently connected
! to my NAS and a hypervisor. Soon, one of these ports will be used to
! trunk the storage VLAN to a LB6M switch, into which all six hypervisors
! and two NAS boxes will connect at 10G. For the moment, these are 
! basically access ports for VLAN 100. Note explicit exclusion of VLAN 1. 
interface 0/49
vlan pvid 100
vlan participation exclude 1
vlan participation include 100
interface 0/50
vlan pvid 100
vlan participation exclude 1
vlan participation include 100
! OK, now things get interesting...
! Here are the two LAG interfaces. Both are configured to run 802.3ad
! to systems running linux, and to do 802.1q trunking for a set of VLANs 
! over the link. This took a while to figure out and get working. The key is 
! the "no port-channel static" directive. This causes the link to be dynamic,
! which makes linux much happier on the other end. For a switch-to-switch
! LAG, it works fine in static mode as long as the config is the same on both
! ends. Both of these are also including VLAN 1 for internet uplink right now.
interface 3/20
no port-channel static
vlan participation exclude 100
vlan participation include 10,15,20,30,200,210
vlan tagging 1,10,15,20,30,200,210
interface 3/21
no port-channel static
vlan participation include 10,15,20,30,100,200,210
vlan tagging 1,10,15,20,30,100,200,210
  • Management VLAN must be explicitly excluded if you don't want it on an interface.
  • Configuration can get messy looking if reconfiguring, as "vlan participation exclude" directives get stale. I wish there was just a "no vlan participation include" directive to remove participation from a VLAN, and interfaces had to explicitly include any desired VLANs. Oh well.
  • To get an interface to be an access port for vlan-unaware equipment, it is important to define "vlan pvid" and "vlan participation".
  • To get a LAG to work for a 802.3ad type aggregation to a linux machine, the "no port-channel static" directive seems to be the magic that makes both sides happy. The link type has to be dynamic for linux to pick up the LAG configuration by itself.
  • To 802.1q trunk over an interface: "vlan participation include" and "vlan tagging"
Other handy commands:
  • copy nvram:startup-config scp://myname@somehost/lb4m.cfg
    • This copies the config from the switch to your host. Your host obviously needs to accept SSH connections. You can also use tftp here, among other things.
  • copy scp://myname@somehost/lb4m.cfg nvram:startup-config
    • This does the reverse: Fetch a config from the named host and path and load it into the startup-config spot. The system will do a quick syntax check and indicate if it passes. Then a "reload" will reload the startup-config into running-config.
    • This is a GREAT way to configure with a static IP without having to use a console cable. The switch won't let you define a static IP address while configured by DHCP. Of course, you have to make sure you don't do anything dumb (and then you WILL need a console cable), but copy the config off of the device to a host, edit the config, add the "network parms" line at the top, then copy it back and reload.
  • telnetcon timeout 15
    • During initial config, this extends the timeout a bit so that it doesn't keep dropping you out.
    • SSH is highly recommended for any sort of "production" access, but telnet is easy and works out of the box with most of the units sold on ebay.

Hope that this all helps someone out there googling for the LB4M.
  • Like
Reactions: Fritz


Active Member
Oct 31, 2013


Active Member
Oct 8, 2014


New Member
Jan 31, 2017

Okay just read full thread and happy now :D

Hi, i just dont get it ..

How can i activate the WEB management?

I want to connect from every port of the switch to it .. And if possible without any vlan or so on ..

Anyone can help me?

i searched for days now and just dont get it working ..
Last edited:


New Member
Feb 14, 2017
I purchased one of these due to all the great information in this thread. Thanks to all who contributed !!


New Member
Feb 10, 2017
I did not modify the connections for the four-pin case fan connectors, so they don't supply correct tach info back to the system board, but I'm OK with that in my application.
Jonathan, I would like to understand what you mean by "modify the connections for the four pin case fans"

As I understand it, no mods are necessary. A four pin PC fan will plugin directly and all four connections are in the correct place. What is different is that Quanta number the pins in the opposite order to PC fans but it makes no difference to connectivity. The polarizing latch is in the correct position. I have traced the schematic for the 3 case fan PCB and confirmed all signals are interfaced in the normal way. The Tacho signal (marked pin 2 by Quanta, normally marked pin 3 for PC fan) has a 10K pullup (R1) to VCC, and feeds the output via another 10K resistor (R2) and a 4K7 resistor (R3) from output to GND. This 3 resistor circuit is identical to the one I have seen in many applications to interface the tacho signal from a 3 or 4 pin fan. The fan tacho signal is open collector, and that circuit provides a pullup to 7V then cuts the signal peak down to 2.8V so it is safe for the input of a 3V3 chip.

Your comment has got me concerned, as I have just finished fitting two 140mm ultra quiet 4pin fans to the case lid. I have plugged them in to the 3 case fan board and had a quick test. As normal, they started at full RPM at power up then cut right down when the firmware was running and stable. That suggests the PWM speed control is working. I was holding the lid and bundle of wires in my hand at the time so didn't get as far as checking the tacho info, and won't be in a position to for a few days, so I would really appreciate it if you, or anybody, could clarify interface of a standard 4 pin fan with the 3 fan PCB. Thanks in advance. The fans I am using are Phanteks PH-H140XP


New Member
Feb 10, 2017
Sorry to reply to myself, but I have done some tests on the original case fan and thought I would
share them here.

Make : AVC
Model : DB04028B-12U
Spec : P144 (This is a special spec for AVC, including
PWM, Tacho, and reliability)
Speed : 13000 RPM
Voltage : 12V (7.2V to 13.2V)
Current : 0.55A
Power : 6.6W
Flow : 23.78 CFM
Pressure : 1.324 in.Hg
Noise : 54dBA

Wiring :
Quanta Pin PC pin Color Function
1 4 BLU PWM input
2 3 GRN Tacho output (open collector)
3 2 YEL VCC (+12V)
4 1 BLK GND (0V)

0 Volts ground was applied to the BLK wire
+12 Volts DC was applied to the YEL wire
A 10K resistor was taken from the GRN wire to +12V
The GRN wire was monitored with a frequency meter
The BLU wire was connected to a signal generator, 10kHz square PWM signal, 5Vpk.pk.

1) As the speed was varied then the frequency at the GRN wire varied
2) The frequency was 433Hz at full speed (13000). Therefore
the Tacho generator complete two cycles per rev and RPM = 30 * Frequency
3) As the pulse width of the signal at the BLU wire was varied then the
speed of the fan varieed in proportion.

PWM duty cyle(%) Frequency(Hz) Speed(RPM)
100 432 12960
90 387 11610
80 355 10650
70 321 9630
60 287 8610
50 256 7680
40 223 6690
30 190 5700
20 158 4740
10 124 3720

The relationship between the speed, N, and PWM %, P, is linear.

Conclusions :
a) The GRN wire has a standard PC fan Tacho signal with an open
collectortransistor output. The output frequency is Fan RPM/30

b) The BLU wire is a standard PC fan PWM input, voltage driven
with a constant frequency square pulse. As the pulse width duty cycle increases then the fan speed increses linearly. The relationship between PWM input and fan speed is : N = 100.45*P + 2674 RPM

c) The fan interface is identical to a standard PC 4 wire fan. Although
Quanta number the pins in reverse, the fan socket on the 3 fan PCB accepts
a standard 4 pin PC fan. The fan will return it's Tacho signal as normal and
be controlled by its PWM input as normal.

(Appologies for the formatting, all the table spacing was munged when posted)



Jan 16, 2015
How do I use the private-vlan feature? I use firmware version
I'm able to define the private vlans like this
vlan database
vlan name 100 "ADMIN"
vlan name 101 "ISOLATED"

vlan 100
private-vlan primary
private-vlan association 101
vlan 101
private-vlan isolated
All the Google results says I should use 'switchport mode', but the device seems to know about 'switchport mode' from an Interface context, but the command is broken and doesn't accept any arguments:
(Switching) (Interface 0/1)#switchport mode ?

(Switching) (Interface 0/1)#switchport mode

Command not found / Incomplete command. Use ? to list commands.
I tried something like this, but it doesn't work.
interface 0/1
vlan acceptframe vlanonly
vlan ingressfilter
vlan participation include 100
vlan tagging 100

interface 0/2
vlan acceptframe vlanonly
vlan ingressfilter
vlan participation include 101
vlan tagging 100
Last edited:


New Member
Feb 10, 2017
Have you looked at the switchport command syntax in the manual, around p95 onward. There's also a section in the Fastpath manual around p30. :

2.1.3 Private Edge VLANs

Use the Private Edge VLAN feature to prevent ports on the switch from forwarding
traffic to each other even if they are on the same VLAN.

• Protected ports cannot forward traffic to other protected ports in the same group,
even if they have the same VLAN membership. Protected ports can forward traffic
to unprotected ports.

• Unprotected ports can forward traffic to both protected and unprotected

You can also configure groups of protected ports, but unprotected
ports are independent and cannot be added to a group. Each group’s configuration
consists of a name and a mask of ports. A port can belong to only one set of
protected ports, but an unprotected port can be added to a group as a
protected port. The group name is configurable by the network administrator.
Use the switchport protected command to designate a port as protected.
Use the show switchport protected command to display a listing of
the protected ports.

2.1.4 CLI Example Example #1: switchport protected

(Ethernet Fabric) #Config
(Ethernet Fabric) (config) #interface 0/1
(Ethernet Fabric) (config) (Interface 0/1) #switchport protected ?

<cr> Press Enter to execute the command.

(Ethernet Fabric) (config) (Interface 0/1) #switchport protected 0
(Ethernet Fabric) (config) (Interface 0/1) #exit Example #2: show switchport protected

(Ethernet Fabric) #show switchport protected