Consider this scenario: you register a desktop computer on the network with a wired network connection. Then, after using that computer on the network for a bit, you whip out a screwdriver and remove the network adapter, install it in a different computer, and proceed to use that computer on the network for a bit. Understandably, with each device presenting the single network adapter’s MAC address, the network will think that these two devices are one and the same. Tools that rely on network information for device identification will also think them to be the same, leading to confusion.
External network adapters–dongles, docks, and the like–are no different. Well, they are different, but only in that they are not internal to a computer and are therefore much easier to move from one computer to another.
This lack of any real technical difference in conjunction with the very real physical difference also leads to some confusion. When registering an internal network adapter, I’ve never seen anyone name it “My NIC Card” or “My Wireless NIC”; rather, they typically name them “My Desktop” or “My Laptop” (or something similar). However, the same is not true for external network adapters; they’re usually registered as “My Dongle” or “My Dock”. This reveals a misconception that the network adapter has some standalone presence on the network when it does not; the network adapter is simply a path for another device to get on the network and should be considered part of that device, just as an internal network adapter generally is.
This misconception leads to two issues, one small and one large:
- (small) Identifying a device that connects to the network via a network adapter that was named after the peripheral rather than the device can be difficult. Imagine getting a call from the IT Security Office about a computer in a lab with five computers. However, this lab also has no ethernet jacks, so five wireless dongles were purchased and now the ITSO needs to know about the computer named “WiFi Dongle 4” (instead of “Analysis Computer” or something more specifically useful). If an external network adapter is intended for use with a specific device, it should really be named after that device (or at least include the device name, e.g. “My MacBook USB-C Ethernet Dongle”).
- (large) Systems that rely on network information for device identification can have issues if an external network adapter is used on multiple devices. In particular, Planisphere will combine records for devices that share an external network adapter (and therefore share a MAC address) into a single device record, with all of the MAC addresses of all of the devices getting quarantined from the network if one of the devices triggers a quarantine. In order to avoid this, an external network peripheral that is intended for use with multiple devices must be classified in Planisphere as a “Shared Network Adapter”. Only Planisphere Admins can assign the Shared Network Adapter classification (for reasons explained on Planisphere’s Shared Network Adapter page), so you’ll need to send the external network adapter’s MAC address and a managing Support Group to planisphere-feedback@duke.edu to get this done.
So, if you’re using or managing an external network adapter, please remember to give it a name that accurately reflects its role as just a part of another device on the network and, if this external network adapter is to be shared by more than one device, get the netwrok adapter properly registered as a Shared Network Adapter in Planisphere.
[Side Note: My example names above may read well, but they’re terrible. Device names in DukeReg are not personal notes to help you tell one device from another; they’re network identifiers that should uniquely and specifically identify the device being registered. For departmentally supported devices, the name should be the name of the device as assigned by IT, generally something like “<DEPT>-<SERIALNUMBER” or “<DEPT>-<SEQUENTIALNUMBER>”. However, examples like that would have really messed up the discussion above, so I went with something simpler and cleaner for the sake of clarity. Sorry(?) about that.]
