What does a Layer 2 switch do if it receives a frame with a

参考答案：F

参考答案：C

正确答案：BC
解析：Explanation:
With store-and-forward, the entire frame. is received by the switch before the first bit of the frame. is forwarded. As soon as the incoming switch port receives enough of the frame. to see the destination MAC address, the forwarding decision is made and the frame. is transmitted out the appropriate outgoing port to the destination device. So, each frame. might experience slightly less latency. Store and forward switching may add latency when compared to other switching methods such as cut through, but it can reduce the amount of errors that become forwarded through a network.

Incorrect Answers:
A. The amount of latency that is introduced with this method of switching is dependent on the size of the frame, as the switch must wait to receive the entire frame. before sending it.

D. The switch must wait for the entire frame. before forwarding it on, and not just the headers.

参考答案：F

参考答案：B

正确答案：A
A 解析：Explanation:
How Does the Switch Find Host MACs?
Let's use the diagram below to help us understand how address learning process takes place.


Let's assume that we have just powered on the switch. It has nothing in its MAC table. We connect the cables from the hosts on the switch interfaces as shown in the diagram. Host A initiates a connection towards Host D, and the following takes place:
1. Host A (interface fe0/0) sends a frame. to Host D (MAC address:0000.43c5.334c).

2. The switch inspects the Source Address in the frame. and notes in its table the MAC address of Host A along with the Interface number from which the frame. originated.

3. The switch inspects the Destination Address in the frame. Since it does not have Hosts D MAC address in its table, it constructs a broadcast frame. and forwards out all interfaces except the interface from where the original frame. arrived.

4. Host D identifies itself as the expected recipient and responds back to Host A. The switch receives the respond frame. on interface fe0/11 and places the SA in its table along with the interface number where the frame. came from.

5. From now on, further communication between the two hosts will be switched to the appropriate interfaces based on the MAC tables entries.

This process takes place every time a new host is attached on the switch and initiates traffic. The switch tries to keep its MAC table up-to-date, therefore if some hosts do not initiate traffic for a certain amount of time, the switch removes them from its table and reinserts them when they begin sending traffic.