On BeagleBone, are the pins for the second Ethernet port available on the expansion header

Reading the TechRef it would appear the the second Ethernet port is
available, but in the SRM there would appear to be no reference to
the second port. Could a second port be added on a cape?


Possibly. I am not sure if all the signals are available depending on the mode you plan to use. I have not had the time document all of the possible options. In the SRM it has the pin numbers for the processor on the expansion header tables. Use those numbers against the pin numbers in the processor data sheet to see if there are enough signals. There should be a grouping in the data sheet for the various ports.


I found the Pin Mux utility on the TI web site (which by way seems to run
quite nicely under Wine - there is no need to run it under Windows) and
was having a look at configuring it to see if I could find the second
ethernet ports.

Is there a definition somewhere of the basic set of Pin configs necessary
for the standard ports that BeagleBone uses? I looked in the SRM and
could not find such a list (but I may have missed it). I am here thinking
of the ports needed by things like the two USB ports and the serial port
that is linked to the USB port.


I do not have a listing of the pins used on the board and their default settings. The only way right now is to look a the schematic and the function they are performing. The USB ports for example can only be USB ports and nothing else, so there really isn’t a pin mux option there except for 1 pin on each of those ports.


From what I can gather from the SRM is that it should be possible
because 'mii1' pins go to the built-in LAN8710A PHY chip and the GPIO
headers expose 'mii2' for the second Ethernet in a certain mux mode.
But you'd need another PHY like the LAN8710A though to use it to add
magnetics or straight CAT5/6 cable to.

Sorry for the ignorance, but

Is it possible to chain 2 (or more) BeagleBones together
without a phy? simply connecting mac to mac ?


Unfortunately some pins are not available to support a cape with a second LAN8710A…

Darn. I was thinking today that I would have a great application for a BBB if it had a second ethernet interface for a separate storage network. Say mount a ceph block device over one ethernet interface and use the other for “business” traffic with no reason to hit the SD or on-board flash at all while it is running. The primary bottleneck in the application I have been investigating so far is disk access. Flash is slow. Network storage is much faster. Separating storage from traffic is even better, particularly when you have only a 100M interface. I have been doing it with vlans but still, the two sorts of traffic compete for interface bandwidth. If I found a genie right now, one of my three wishes would be a dual ethernet BBB.

what about using the onboard ethernet for storage, and USB ethernet
dongle for external connection?