4.22 Consider the procedure to maintain the spanning tree of a BLAN. Which of the following statements are correct for the transmission of TCN (topology change notification) BDPU ?
A. (a) A bridge will send a TCN BDPU to the root bridge if one of its port changed state (from blocked state to forwarding state, or vise versa)
B. (b) The TCN BPDU will be delivered to the root bridge along the spanning tree.
C. (c) The TCN BPDU will be delivered to the root bridge along multiple communication paths.
D. (d) The TCN BPDU is delivered via a reliable, hop-by-hop method.
E. (e) The TCN BPDU is delivered via a best effort method.
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In IEEE 802.11 Wireless LAN, the signals are propagated through which media ?
A. (a) Coaxial cable
B. (b) Optical fiber
C. (c) Twisted pair
D. (d) Space (air)
E. (e) Power Line
What are the purposes of RTS and CTS control frames used in IEEE 802.11 wireless LAN ?
A. (a) Reserve the wireless channel for a time period
B. (b) Informs all nearby nodes that a transmission is about to begin
C. (c) These two frames also contain data to transmit.
D. (d) The sender is asking the receiver to send back a frame after a time period
E. (e) The duration field in the RTS and CTS frames is used to specify the time period
For IEEE 802.11 CSMA/CA protocol, which of the following statements are correct for any node that sees a CTS frame ?
A. (a) It is close to the sender and therefore it can transmit for the period of time specified in the CTS frame.
B. (b) It is close to the receiver and therefore cannot transmit for the period of time specified in the CTS frame..
C. (c) It is not close enough to the receiver to interfere with it, so is free to transmit..
D. (d) It is not close enough to the sender to interfere with it, so is free to transmit.
E. (e) It is close to the receiver and therefore can transmit for the period of time specified in the CTS frame.
For IEEE 802.11 CSMA/CA protocol, which of the following statements are correct for any node that sees an RTS frame ?
A. (a) It is close to the sender and therefore cannot transmit for the period of time specified in the RTS frame.
B. (b) It is close to the sender and therefore can transmit for the period of time specified in the RTS frame.
C. (c) It is not close enough to the receiver to interfere with it, so is free to transmit.
D. (d) It is not close enough to the sender to interfere with it, so is free to transmit.
E. (e) It is close to the receiver and therefore can transmit for the period of time specified in the RTS frame.
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