Data link layer of computer network

1. In the computer communication network, the error rate is required to be less than ten -6 times, that is, the average transmission of 1 million bits to allow 1 bit error.

2. The TCP Protocol in the Transport layer has a control mechanism that guarantees end-to-end reliable delivery, so why is it necessary to require error detection in the PPP protocol?

If not in the Data Link layer error detection, then the error has occurred in the frame will also be in the network to continue forwarding, wasted a lot of network resources. However, there is no need to correct the data link layer. Because error correction is not only to find errors, but also to correct the mistakes.

3. What features do we usually not need to add to the PPP protocol?

1) Error correction.

2) flow control; Usually the sender sends the rate must make the receiver in time to receive, when the receiving party is too late to receive, arrive at the receiver's frame is queued to wait for processing. End-to-end traffic control is the responsibility of the transport layer's TCP .

3) serial number.

4) multi-point line.

5) Half-duplex or single-link.

4.

Data link layer of computer network