Why connect a hub and a switch with a crossover?

Question

Computer networks

Why connect a hub and a switch with a crossover?

Answer 1

Depicted something by virtue of his abilities.
This is how a 'straight' cable (not) works. The receiver connects to the receiver, the transmitter connects to the transmitter. Roughly speaking, there is no connection.
This is how a cross cable works. The receiver is connected to the transmitter of the opposite side. The parties are able to exchange signals.
Do not pay attention to the marking of the connectors, the contacts are signed (pin 1-3.6).

Answer 2

If you are preparing for the CCNA level exam (where this question is relevant), then you can divide the types of devices into two groups. One will contain routers and computers/servers, the other will contain switches and hubs. When connecting devices from different groups (router and switch, computer and hub), a straight-through cable is used, when connecting devices within a group (router and computer, hub and switch), a crossover cable is used.
There is MDI/MDI-X autosense technology that automatically recognizes the "pinout" of the neighbor's port. As far as I understand, for it to work, the port must be configured in auto-detection mode for both media speed and duplex. Recently, this technology is used almost everywhere.

Answer 3

Physical meaning (for now, we are considering connecting MDI to MDI, computer / router to computer / router). On device A, the transmitter is connected to pins 1,2 on the 8p8c connector (rj-45 colloquially), the receiver is connected to pins 3 and 6. Similarly on device B. When using a 'straight through' cable, the transmitter of device A is actually connected to the transmitter of device B Similarly, the receiver of device A is connected to device B. It is logical that the signal from transmitter A does not reach receiver B.
A 'crossover cable' is used to solve the problem. Pins 1 and 2 on one side of the cable are connected to pins 3 and 6. Thus, the transmitter of device A is connected to receiver B and vice versa. Accordingly, device B successfully receives the signal from device A and further processes it.
A similar picture for MDI-X (hubs, switches)

Answer 4

Now almost all hubs and switches are insensitive to the type of twisted pair and automatically adjust, but they used, as it was previously required for telephony, an uplink of the hub-hub type.

Answer 5

Why? *
Study (Lenin spoke about study) en.wikipedia.org/wiki/Medium_Dependent_Interface
* on modern equipment