How do you determine which physical network port software is referring to?

Fritz

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Apr 6, 2015
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This has always been a pet peeve of mine. Software labels a network port but gives no freaking clue as to which physical port it is. I'm getting ready to install pfSense in a VM and I'm running into this problem. The instructions say take note of the MAC address, Well duh, how do you determine which MAC address goes with which port? I'm using a 4 port Intel server NIC and I have no idea which whether the ports are numbered top to bottom or bottom to top and I have no idea whether or not the MAC addresses follow the same convention. Also, Hyper V and pfSense name the port which further adds to the confusion. So is there any standard way of determining which port is which? And also, some SW like Supermicro Superdoctor numbers the ports. Does all SW number the ports in the same order? Is there a standard?

TIA
 

klui

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Feb 3, 2019
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Try ethtool -p portName or go into the NIC OPROM to see if there is an ability to flash the LEDs like in Mellanox cards. ethool either manipulates the port itself or requires the NIC driver to do that.
 
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BShoppy

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Apr 16, 2021
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I just ran into this yesterday while trying to troubleshoot something in my setup. On my Brocade ICX6450 I disabled one port at a time and checked the hypervisor to see which one showed as link down. Turns out they were exactly like I expected, but at least I was 100% sure after that.
 
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T_Minus

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Feb 15, 2015
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With pFsense I have my hardware labeled on the physical ports 1 - 4 and then in pfsense i associate those #s as well so they match. I also tag my newtork cables 1-4 depending on their usual\static position when plugged in, I do this so I can swap cables around if I'm testing something or want to try a new config so I know which go where to "go back" to where I was.
 
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NateS

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Apr 19, 2021
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I tend to go low tech for this sort of stuff: my supermicro motherboards came with physical printouts that labeled the logical names of each port; and immediately on putting it in a case, I transferred those labels to the ports with a sharpie.
 
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Markess

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@Fritz ALWAYS seems to post questions/comments on stuff I'm working on at the same time. Freaky.

I was asking myself the same thing last week on a (Dell branded) Silicom PE2G4I35 adapter, which is i350AM4. On that one, the lowest numbered port wound up being at the top, and the highest at bottom (closest to the PCI-E slot). Ubuntu calls them enp5s0f0 through enp5s0f3.

I figured it out using the @Tom5051 method of device identification, and locked that identification in for posterity using the @T_Minus method :p. Before that, I'd always used the @Markess method for the last several decades, which consisted of "I'll write it down/label it later" followed later by "Well !@#$, now where did that one go!" :rolleyes:
 

Fritz

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Think I have the 6 port version of that card. Nice to know the port numbering is bass ackwards. Should save me some grief if I can remember. :p
 
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Markess

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Think I have the 6 port version of that card. Nice to know the port numbering is bass ackwards. Should save me some grief if I can remember. :p
Because nothing in life should be easy.....don't forget....that your card is actually an i350t4 chip and an i350t2 chip on a single PCB. So, if you see odd device IDs where it looks like a group of 4 with similar names and a group of 2 with similar names, and not a group of 6...that's why.
 
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Fritz

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There's always a gotcha in the way. I just installed the card in a Server 2022 box to play around with it. Judging by the enormous heatsink I assume it draws a good bit of current.
 

Markess

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There's always a gotcha in the way. I just installed the card in a Server 2022 box to play around with it. Judging by the enormous heatsink I assume it draws a good bit of current.
The NIC chips themselves draw next to nothing. Its the PLX chip(s) that are there to connect the two i350 chips together on one card that are drawing all that power. Two separate i350 cards (one 4 port and one 2 port) would draw less power, but then you'd have two slots occupied instead of just one.
 
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Fritz

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The NIC chips themselves draw next to nothing. Its the PLX chip(s) that are there to connect the two i350 chips together on one card that are drawing all that power. Two separate i350 cards (one 4 port and one 2 port) would draw less power, but then you'd have two slots occupied instead of just one.
Thanks. Think I'll stick with the one card. I try not to go overboard for the sake of saving energy. Rates here aren't too bad so I'll just pay for the privilege of using what appears to be a top notch NIC.