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September 27th, 2018 07:00
Mac Address assigned to docking NIC keeps resetting
Dear experts:
We have roaming users with notebooks Latitude 7480. When they go to other location of our enterprise, they connect to our LAN through a docking station (DS1000). This docking station has its own NIC (Realtek USB GBe Controller).
We assign this notebook a local IP address through our DHCP Server, but in order to do this, we have to "spoof" the mac address of the notebook to the adapter in the docking station ("Locally Administered Address" in Advanced propertis of the docking NIC).
This is working fine; but sometimes this value resets to the value "not present", and the notebook can not get the proper IP address.
Any ideas about why this value resets itself?
Thank you very much,
Mr.Clinker
jphughan
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September 27th, 2018 08:00
UPDATE: It's not mentioned in the DS1000 manual, but this spec sheet for the DS1000, which appears genuine despite being hosted on a third-party site, indicates that the DS1000 does support MAC address passthrough. In that case, make sure this feature is enabled in the BIOS of your 7480s and then update the BIOS/firmware of the 7480, the firmware of the DS1000 docks themselves, and perhaps the Realtek NIC driver. You can find the last two under the DS1000 support page here.
jphughan
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September 27th, 2018 08:00
Even with identical hardware models, if the system detects a different unique example of that identical hardware, it will treat it as a unique device with its own settings -- because after all in some cases you might have two identical devices for which you want to use different settings. For example, servers might have dual or quad-port NICs that are all the same model, but they might be using each in a different way that requires different optimizations. And if you're configuring the dock NIC to match the MAC of the internal NIC, another possibility is that the system doesn't allow you to configure the same MAC address on two active network interfaces at the same time.
The proper solution here is to use a Dell dock that supports "MAC address passthrough", like the WD15. In this scenario, as long as this option is enabled in the system's BIOS (it's on by default), when the system is connected to a dock that supports this feature, the system sends the MAC address of its own internal NIC to the dock (and I believe disables its internal NIC to avoid the possibility of MAC address duplication on the network). So in addition to not having to worry about moving from one dock to another, your system will be identified the same way whether it connects to the network through a dock or via a cable plugged directly into the system. I would have thought the DS1000 would support this since it basically looks like a WD15 embedded into a monitor stand, but perhaps not. Dell's portable "mini-dock" dongles like the DA300 also support this feature, fyi.