lan switch keepalive

[fly]

we found one port of etherchannel went into errdisable, the reason is loopback.

switch will send keepalive through all interface except uplink and fiber i have two questions

1、what is uplink, is trunk port uplink?

2、keepalive frame sorce mac address and destination mac address  is itself,   how can switch detect interface status from keepalive mechanism.

   switch A send switch B a keepalive frame. how can swich B process this frame, switch B will send back a response frame (switch B create a new frame), or Switch B just send back switch A original frame.

  or Switch A just finish sending it's frame successfully  and don't expect to receive any respond.  from this can prove link status is ok?

thank you!

Tom

[fly]

no one here? If switch B receive Switch A keepalive frame form it's interface. how to handle it ? discard frame? oh, response a new frame. I capture a packet on computer, found computer does't process it, and don't response. because src mac and destination mac it is itself which generate it. if there is a loop, switch B learn switch A mac address from another interface , does switch B send this frame to that interface, and eventually this frame will come back to swich A? thank you! tom