Auto-MDIX

[ciscobuddies]

Hi,

I am wondering how technically auto-MDIX works (i.e. what is the cause which allow to software replace rx with tx). On one of the page I have found that auto-negotiation must be enabled to have this functionality fully working. Can you please comment what is the idea behind it?

Thank you,

Ttoy

[smehrnia]

Hi,

For auto-MDIX to operate correctly, the data rate on the interface and duplex setting must be set to "auto", that way a pseudo-random number generator decides whether or not a network port will attach its transmitter, or its receiver to each of the twisted pairs used to auto-negotiate the link.

When two auto-MDIX ports are connected together, which is normal for modern products, the algorithm resolution time is typically < 500 ms. However, a ~1.4 second asynchronous timer is used to resolve the extremely rare case (with a probability of less than 1 in 10²¹) of a loop where each end keeps switching.

plz Rate if it helped.

Soroush.