why hub-hub connection needs cross over cable?

johnifanx98johnifanx98 Member Posts: 329
in CCNA & CCENT
I understood switch-switch requires crossover since switches need to talk each other for STP protocols alike. But hub looks like just signal duplicator. Does it need to talk to another hub like switch does?
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  • zrockstarzrockstar Member Posts: 378
    It's not about talking to each other, it is about how the jacks on the device are pinned. If you connect hub to hub with a straight through, the TX pins will end up sending to the TX pins, and receive pins to receive resulting in no transmission. A cross over switches the TX/RX pins so data can flow.
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  • johnifanx98johnifanx98 Member Posts: 329
    zrockstar wrote: »
    It's not about talking to each other, it is about how the jacks on the device are pinned. If you connect hub to hub with a straight through, the TX pins will end up sending to the TX pins, and receive pins to receive resulting in no transmission. A cross over switches the TX/RX pins so data can flow.

    True. Just realized the real meaning of "same type" device... Hub/switch is one type, and host/router is another type in terms of physical layer spec as you've described. Cross over for connection between same type device, and straight through for different type devices...
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