It seems for port 3 the pairs A and B are swapped. Also pair C and D are swapped. Can you confirm this ?
I double checked my pcb design and cables for crossings, but only port 3 is reporting swapped pairs in my test setup. As this will not affect the correct functioning of the port it is no problem, but documentation/datasheets should be correct.
There is no difference in the routing of port 3 in comparison to any of the other ports.
They are all mapped as:
Pin 1: C-
Pin 2: C+
Pin 3: D+
Pin 4: D-
Pin 5: B+
Pin 6: B-
Pin 7: A+
Pin 8: A-
Then, using the supplied cables, this maps to the RJ-45 connector as below.
This is the standard mapping for RJ-45 straight cables (see below), and is how all of our gigabit ethernet boards are mapped.
What device are you using to check cable mapping, and is that device expecting a straight or crossover cable?
We use the Copper Test available in Cisco SG3xx -series to verify cable mapping, but I have found that this test is very unreliable. Successive tests show different results and after repeating the test a few times it ends with a fault message.
So I guess there is no issue at all with swapped pairs.
test is described here :
1 Like