Quanta LB4M 48-Port Gigabit Switch Discussion

Chuntzu

Active Member
Jun 30, 2013
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I have not. I will have to give this a shot. Though, isn't dhcp snooping there to prevent some dhcp broadcasts? Or once it is enabled it allows the broadcasts? Thank you for the advice.
 

spyrule

Active Member
Its there to filter out DHCP requests from untrusted DHCP sources, however it seems like this is a common problem with cisco. It sometimes blocks DHCP requests you want to get through. Thats not based on personal experience, but a quick google of your problem and reviewing 5-6 different threads saying basically the same thing.
 

spyrule

Active Member
On a complete side note, I got my LB4M on Friday, havn't had time to do anything but power it up and confirm WebUI and Serial connections. It's definitely a little louder then I wanted, so I've modified the top panel and installed two 80mm Noctua PWMs and I've ordered two Noctua 40mm fans for the Power supply (I'm only using one PSU at a time, so I should be able to re-use the other fans when/if the "first" power supply dies.
 

T_Minus

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Feb 15, 2015
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Do the SFP+ ports communicate with each other at 10gb or is it only aggregate 10gb from the 1gigE ports?
 

T_Minus

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"it seems one 10g port of each chip is used to provide the 2 SFP"

Does that mean each chip provides 10g each/separate to each SFP

Or does that mean 1 10g port is split between 2 SFP?
 

spyrule

Active Member
"(there're 2 of them in it, each providing 24 1g ports and 4 10 or 12g ports - it seems one 10g port of each chip is used to provide the 2 SFP+ ports, and probably the 3 remaining high speed interfaces are used to interconnect the two ICs inside the switch)"

well, each chip has 4 10G capable paths. 3 are used for inter-chip communication I'd guess @ 12G (basically more bandwidth then all the ports combined on each chip, so thats good) and one port specified for 1 x 10G port. So, to me that's a full 10Gig path for 1 SFP, and since there's 2 chips, that makes 2 x 10Gig paths, 1 for each SFP.

The way I see it, the only place there "could" be a bottleneck would be via the interconnect. But since each chip only support 24G+10Gig = 34Gig, and the interconnect maxes out at 36Gig, there is no chance of bottleneck. However, the only thing that isn't specified (that I can find) is if the interconnects are running at 12Gbps bidirectional, or asynchronous. I'd think that would be bi-di, so in full path bandwidth that would be 72Gbps, which is still more then enough, assuming all the physical connections are running bi-di as well.
 

T_Minus

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Awesome thanks for that.

Got some offers in, hopefully I can give 2 a shot with my new Mellanox cards :)
 

bevz

New Member
Mar 23, 2015
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Hello, long time lurker first time poster.

Just got my LB4M off ebay with only 1PSU. I plugged it in and was literally blown away how loud this sucker was. Around 67-69dB with a rudimentary phone app taking measurements. As someone mentioned before the loudest component is the PSU. I was really disappointed that this thing is louder than a Dell R715! I got to it and removed the PSU cover which had seized up screws so I had to drill a few out and swapped in quieter Evercool fans from here Evercool EverCool 40mm Ball Bearing Case Fan FAN-EC4010M12CA - Micro Center

Now it reads 42-44dB! Perfectly comfortable and just a hair louder than my Dell R730. The temps are only a little bit warmer around 45c but so far it's working with the two Brocade 1020s. +

My only issue is after setting jumbo frames everywhere between the switch, vmware, and the NICs in windows I'm only able to sustain about 4.6-4.7Gbps using Lanbench between two VMs on seperate hosts. Netio depending on the packet size spikes up to 6.7Gpbs but the only thing I haven't messed with are C states for either hosts.

Thanks for all the great info in this thread!
Hope all is well with everyone!

I picked up a few LB4M off ebay. With dual PSU. I went out to amazon and picked up the Evercool 40mm Ball Bearing fan, Amazon.com: Case Fan, 40x40x10mm, Ball Bearing, 3-pin: Computers & Accessories

Unfortunately they are NOT spinning. Has anyone else try the same Evercool fan, or had success with other 40MM fans? I verified the fans I replaced were spinning... Could it be a pin order issue?

Appreciate the assistance.
 

spyrule

Active Member
Be aware that the stock fans actually suck air from inward and blow out backwards. I'd recommend flipping the fans around and suck cold air in, and if your cutting the lids to install 80+mm fans, set the fan closest to the front to suck outward, and the fan near the back to blow inward. This creates a very nice airflow that promotes cooling across the main CPUs, and the psu's.
 

bevz

New Member
Mar 23, 2015
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If you are replacing the PSU fans, note that I reported back in post #97 that the power supply fan headers do not use standard header pinouts. In other words a rewire of the 3pin fan connector is required.
My bad, must of over looked your post. They are working now. I also flipped the fans so they are sucking cold air in. Thanks for followup!
 

spyrule

Active Member
Those are the physical dimensions of the box itself, add another 1-2" at the back for safe operation of the plug, and ventilation space (the rear stock fans are intakes).

If your tight on space, I'd recommend ordering two L shaped power cords to save you an inch of space.