What is CRC and how does it works?

What is CRC and how does it works?

 

CRC errors refer to Layer 1 or 2 issues.

Two things you should check :

1. Both the ends of the interfaces have some speed and duplex settings.

2. Check the physical cabling or copper line.

 

I nput I nput I nput : (total) : 92698557257 packets, 66876615402218 bytes 92698122077 uni casts, 1528 broadcasts, 433652 multi casts, (normal) : 92698557257 packets, — bytes 92698122077 uni casts, 1528 broadcasts, 433652 multi casts, 0 input errors, 0 runts, 0 giants, 0 throttles O CRC, O frame, overruns, 0 aborts — ignored, parity errors 0 pauses 0 pauses

 

 

CRC (Cyclic Redundancy Check) is apolynomial function  on the frame which returns a 4B number in Ethernet Frames.

Figure 4-2 Ethernet and IEEE 802.3 Frame Formats Ethernet F-SE Ength, in FSH Ength, in 7 7 o 2 O O F add 6 add regs Scuræ addres IEEE .3 2 SQJræ Length addres 40-15m 46-150 BCC .2 hæder and data 4 FCS 4 FCS SOF = Startof-frame delimiter FCS = Frame chæk Awenæ

 

It will catch all single bit errors and a good percentage of double bit errors. It is thus meant to ensure that the frame was not corrupted in transit.

 

The CRC is an error detectionalgorithms and is designed to maximize the probability of detecting errors using only a small number of redundant bits. The CRC-32 gives strong protection against common bit errors in messages that are thousands of bytes long. If you want to know more about how does it works, I recommend a book called <Computer Networks - A systems approach>. The CRC algorithm is discussed around page 92 through 102.

 





posted @ 2016-10-26 13:18  rong-shao  阅读(186)  评论(0)  编辑  收藏  举报