CRC check on T lines

[sarahr202]

HI every body

Let say we have a t1 line as shown below:

CPE1----T1--------C01-----------T1--------C0---------T1--CPE2

Let say we are using ESF framing.    In ESF, we have CRC that can be used to detect errors. My question :is this error detection by crc used between end devices i.e cpe1 and cpe2? or it can be used say cpe1 and co1?

thanks and have a great weekend

[acampbell · Accepted solution]

Sarah,

To the best of my knowledge the CRCs in your T1 diagram are on the single segments

IE CPE1 to CO1.

Any end to end (CPE1 to CPE2) would have to be error checked higher up the stack at say the TCP layer

Regards,
Alex.
Please rate useful posts.

[Leo Laohoo · Accepted solution]

I'm with Alex.

CRC will only check between the CPE and the next hop.

If you want a point-to-point error check, nothing beats a Bit Error Rate (BER) test.

Because of the greater emphasis on software-based BER test, I've grown wary of their inaccuracy.  I've always insisted in ordering a hardware-based BER test whereby the telco will send a tech and a box to your appointed location and install the tester. 

[sarahr202]

Thanks ALex and Leolaohoo.